REVIEW ARTICLE
CD20+ Mycosis Fungoides: A Report of Three Cases and Review of the Literature Joshua W. Hagen, PhD, MD,* Jochen T. Schaefer, MD,† and Cynthia M. Magro, MD‡
Abstract: Mycosis fungoides (MF) is the most common of the family of cutaneous T-cell lymphomas, accounting for 65% of all cases of cutaneous T-cell lymphomas. The classic phenotypic profile is one defined by CD4+ T cells showing a reduction in the expression of CD7 and CD62L. There are 3 previous reports describing CD20 expression in MF. The cell surface antigen CD20 is a transmembrane glycosylated phosphoprotein expressed in the early stages of B-cell development before differentiation into plasma cells. Two male patients, aged 14 and 44 years, presented with persistent truncal plaques up to 8 cm of 1 and 4 years duration, respectively. A third patient, an 80-year-old female, presented with a 1-year history of progressive nodules involving the head and neck area. Cases 1 and 2 both responded to topical treatment modalities. The biopsies in cases 1 and 2 showed features typical of plaque stage MF, whereas case 3 was compatible with follicular MF with tumor stage transformation. Phenotypically, the aberrant cell populace demonstrated a CD4+, CD72, and CD62L2 phenotype; at variance with classic MF was the expression of CD20. Although there were a few PAX5-positive staining cells, definitive colocalization studies were negative. Other B-cell markers and heavy chain immunoglobulin rearrangement were not detected. There are a growing number of reports describing T-cell lymphomas and leukemias with CD20 expression. Of the 6 CD20+ MF cases reported in the literature to date, 3 have been associated with a more aggressive clinical course; all but one case have occurred in males. Key Words: CD20, T-cell lymphoma, mycosis fungoides (Am J Dermatopathol 2013;35:833–841)
INTRODUCTION Mycosis fungoides (MF) is the most common of the family of cutaneous T-cell lymphomas, accounting for up to 65% of all cases of cutaneous T-cell lymphomas.1 It is considered an indolent lymphoproliferative disorder most commonly presenting with pruritic plaques and patches involving photoprotected skin. MF is approximately twice as common in men as in women and shows racial predilection, with From the *Department of Medical Education, Weill Medical College of Cornell University, New York, NY; †Departments of Dermatology and Dermatopathology University of Connecticut Dermatology Associates, University of Connecticut Health Center, Farmington, CT; and ‡Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY. The authors declare no conflicts of interest. Reprints: Cynthia M. Magro, MD, Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, Box 58, Room F-309, 1300 York Avenue, New York, NY 10065 (e-mail: cym2003@ med.cornell.edu). © 2013 Lippincott Williams & Wilkins
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blacks affected at almost double the frequency noted in non-Hispanic whites. The majority of cases are diagnosed in the fifth and sixth decades of life, whereas adolescents are only rarely affected. The diagnosis of MF relies heavily on both clinical presentation and histopathology, that latter of which is classically characterized by a superficial epidermotropic infiltration of neoplastic CD4+ T cells.2 The cell surface antigen CD20 is a transmembrane glycosylated phosphoprotein encoded by the MS4A1 gene and expressed in the early stages of B-cell development before differentiation into plasma cells.3 It is widely believed that CD20 represents a relatively specific marker of B-cell differentiation, although there are a growing number of reports describing T-cell lymphomas and leukemias with CD20 expression detected by antibodies directed against a variety of CD20 epitopes.4–18 In addition, CD20 is expressed on a small population of reactive T cells where the staining pattern is weak compared with CD20 expression in B cells.19 The literature reveals only 3 reports observing CD20 expression in the context of MF. One of the first reported cases of CD20+ MF was presented in the context of rare peripheral T-cell lymphomas with CD20 expression, which the authors categorized as MF.10 This first case report was soon followed by an additional case series detailing a spectrum of CD20+ T-cell lymphomas that included 2 individuals with a clinical presentation and morphology meeting diagnostic criteria for MF.20 We report 3 additional patients showing pathology consistent with CD20+ MF, expanding the number of reported cases of this extremely rare immunophenotypic variant. The pathogenetic basis of CD20 expression in cutaneous lesions of MF is explored.
MATERIALS AND METHODS Phenotypic Studies Tissue sections of 5-mm, formalin-fixed paraffinembedded tissues were cut on positively charged slides. The slides were then treated with xylene and 95% alcohol and rehydrated before staining with antibody. In each case, comprehensive phenotypic studies were conducted including Beta F1, CD2, CD3, CD4, CD5, CD7, CD8, CD20, and CD62L. The methodology has been previously described. In addition in both cases, colocalization studies were conducted to assess for dual expression of CD20 and CD3 and that of PAX5 and CD3. The double staining for CD3/CD20 was carried out by using a 2-step immunohistochemistry procedure. The sections were incubated for 30 minutes and stained with each antibody sequentially, first CD3 and then CD20, using the commercially available Leica Biosystems www.amjdermatopathology.com |
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and following the protocol. The CD3 antibody was incubated at a dilution of 1:100, and the CD20 antibody was undiluted and ready to use. In each of the colocalization studies, a red chromagen was used for CD20, whereas the T-cell immunostain used a daminobenzidine technique. In regard to the PAX5 colocalization studies, the same procedure was carried out except a red chromagen was used to detect CD3 and a diaminobenzidene stain was used for visualization of PAX5.
Molecular Studies DNA was extracted from formalin-fixed paraffinembedded tissue. A polymerase chain reaction (PCR) reaction to assess the presence of immunoglobulin heavy chain gene rearrangements was performed using FR3 and JH primers. The products of these reactions were analyzed by polyacrylamide gel electrophoresis. To increase the sensitivity of clonality detection in lymphoma, additional PCR reactions were performed to assess the common rearrangements of immunoglobulin kappa light gene using the BIOMED2 assays. Two multiplex PCR reactions were conducted using six sets of primers in each reaction that are hybridized to the immunoglobulin kappa light gene locus.21,22 PCR products were analyzed by polyacrylamide gel electrophoresis.
CASE REPORTS Case 1 A 14-year-old boy presented with a solitary, discolored erythematous lesion on the right shoulder that had been present for 1 year without significant change in size or appearance. Patientinitiated empiric home therapy with topical cortisone cream was reported to result in some partial resolution of the lesion at least in regard to the extent of dyschromia. There was no history of skin cancer for the patient or his family, and the patient was otherwise well. Examination revealed a 3-cm erythematous patch with central
clearing on the right upper back. Two 4-mm punch biopsies were taken for further analysis.
Case 2 A 44-year-old man presented in 2011 with multiple erythematous patches and plaques up to 6–8 cm in diameter, predominantly in the lower back and sacral area. The patient first noticed skin lesions in 2006. The lesions have had a waxing and waning clinical course. Topical steroid therapy was without significant clinical effect. The patient’s medical history was significant for arterial hypertension, which has been treated with nebivolol. The family history was negative for hematologic disorders.
Case 3 The patient was an 80-year-old female who presented with a history of a recurrent rash largely localized to the face, chest, and back. Her medical history was remarkable for hypertension and hyperlipidemia. Her medication history included allopurinol, Metoprolol, nifedipine, simvastatin, and hydrochlorothiazide. Physical examination revealed crusted nodules on the neck and posterior right ear.
Light Microscopic Findings The biopsies in cases 1 and 2 appeared similar, showing a constellation of findings typical for plaque stage MF (Figs. 1, 2). In both cases, there was a superficial mononuclear cell infiltrate that assumed a nondestructive band-like lichenoid pattern. The infiltrate was of lesser intensity in case 2 compared with case 1 and was associated with dermal sclerosis (Fig. 2A). There was basilar and parabasilar colonization by atypical cerebriform lymphocytes (Figs. 1B, 2B). A greater extent of intraepidermal lymphoid atypia was noted compared with the lymphocytes within the dermis. In case 1, the inflammatory infiltrate also exhibited folliculocentricity. In case 2, there was an element of attendant basilar vacuolar change with incipient dyskeratosis (Fig. 2A, B). Rare Langerhans cell rich vesicles imparting an almost eczematoid morphology to the process was also noted in case 2. The lymphocytes were small and cerebriform in quality; the atypicality was best appreciated under oil examination. In case 3, there was a striking large cell infiltrate of
FIGURE 1. A, Case 1 shows a band-like lymphocytic infiltrate lying in close apposition to the long axis of the epidermis. A narrow grenz zone separates the infiltrate from the overlying epidermis. There is a component of laminated sclerosis. Significant deeper seated extension of the infiltrate is not seen. B, There is colonization of the epidermis by lymphocytes unaccompanied by significant destructive epithelial changes. Lymphocytes extend into the mid and upper spinous layers of the epidermis. The lymphocytes are hyperchromatic and exhibit cerebriform morphology.
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FIGURE 2. A, In case 2, the biopsy shows a band-like lymphocytic infiltrate lying in close apposition to the epidermis. There is attendant dermal sclerosis. Focal epitheliotropism is present unaccompanied by any obvious destructive epithelial changes. B, A higher magnification shows a passive pattern of lymphocyte migration into the epidermis with dominant localization to involve the basal layer. There is a lack of epithelial destruction. cerebriform and immunoblastic appearing lymphocytes involving the superficial half of the dermis. The infiltrate was largely nonepidermotropic, although there were small foci of epidermotropism (Fig. 3). Prominent involvement of the adventitial dermis of the hair follicle along with marked infiltration of the outer root sheath epithelium was observed. There were also admixed plasma cells present throughout the depths of the biopsy.
Phenotypic Studies In case 1, there was extensive highlighting of the infiltrate for CD3 and CD5 (Fig. 4A). However, there was a marked reduction of CD7 with only 30% of the intraepidermal and dermal lymphocytes exhibiting immunoreactivity (Fig. 4B). The CD4 to CD8 ratio was very high (Figs. 4C, D). CD30 studies were negative. A CD20 preparation showed extensive positivity of the dermal infiltrate; a cytoplasmic membrane pattern of staining was observed; the
staining intensity was strong (Fig. 5). A combined CD3 and CD20 stain appeared to show colocalization of several neoplastic T cells with CD20 (Fig. 6). A curious finding was a pattern of differential staining with extensive and prominent CD20 staining of lymphocytes closest to the epidermis (Fig. 5A). The lower half of the infiltrate showed an absence of positivity for CD20. The dual CD3/ PAX5 stain did not show any colocalization amid the lymphocytes within the dermis. With regard to case 2, the infiltrate was phenotypically aberrant by virtue of the high CD4 to CD8 ratio in excess of 5:1 and the selective loss of CD7 especially amid the more atypical lymphocytes within the epidermis and dermis with a greater degree of diminution of expression within the intraepidermal compartment (Figs. 7A–D). Of the infiltrate, 30%–40% was positive for CD62L, whereas the intraepidermal lymphocytes were essentially negative for CD62L. A combined CD20/CD3 stain showed colocalization of dermal and intraepidermal atypical lymphocytes for CD20 and CD3, indicative of a dual expression of CD3 and CD20 (Figs. 8A, B). Approximately 30% of the intraepidermal and dermal lymphocytic infiltrate showed dual staining for CD20 and CD3. The staining intensity for CD20 was moderate to marked in degrees, exhibiting a diffuse granular cytoplasmic membrane pattern of immunoreactivity. In case 2, there was also focal staining of intraepidermal and dermal T cells for PAX5, although the number of cells showing positive staining was less than that observed for CD20. However, the CD20 and PAX5 colocalization studies were essentially negative. With respect to case 3, the infiltrate was extensively highlighted by CD2, CD3, and Beta F1 (Fig. 9A). There was a marked reduction in the expression of both CD7 and CD5 (Fig. 9B). The infiltrate was almost exclusively of the CD4 subset (Fig. 9C). There was almost an equivalent pattern of staining for CD20 as that noted for CD3 (Fig. 9D). The CD3+ cell populace showed colocalization with CD20. The staining intensity for CD20 was strong and similar to that observed for CD2, CD3, and CD4 qualitatively and quantitatively.
Molecular Studies FIGURE 3. The biopsy shows a striking folliculotropic lymphocytic infiltrate. There is marked infiltration of the adventitial dermis and outer root sheath epithelium by lymphocytes. Ó 2013 Lippincott Williams & Wilkins
T-cell receptor studies were performed on all 3 cases. Cases 1 and 3 showed a monoclonal rearrangement, whereas a polyclonal pattern was noted for case 2. Illustrations of the monoclonal and polyclonal patterns for cases 1 and 2 are provided in Figure 10. www.amjdermatopathology.com |
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FIGURE 4. A, The infiltrate is highlighted by CD3. B, There is a marked reduction in the expression of CD7. Eighty percent of the infiltrate is without significant staining for CD7. C, There is marked positivity of the infiltrate for CD4. D, In contrast, the infiltrate shows minimal staining for CD8. Heavy chain immunoglobulin gene rearrangements were not uncovered in case 1. They were not assessed in the other 2 cases.
DISCUSSION We have presented 3 cases of MF that represent an interesting departure from the typical diagnostic picture for MF by virtue of the atypical expression of the pan B-cell marker CD20. In 2 cases, both patients were males exhibiting a stable nonprogressive clinical course. One patient was an elderly female with tumor stage follicular MF. In the one young adolescent male, the presentation was in the context of unilesional MF. A recent series addressing pediatric MF found a higher incidence of unusual variants of MF including unilesional, hypopigmented, and purpuric MF. The unilesional cases accounted for 20% of the reported cases in this particular series.23 In our case, over and above the aberrant phenotype, the identification of T-cell clonality provided additional corroborative evidence regarding the categorization as MF.
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An extensive search of the literature revealed only 3 previous cases of CD20+ MF (Table 1). The first reported case by Sen et al10 reported a 53-year-old male with lower extremity patches and plaques showing dense dermal lymphocytic infiltrates exhibiting epidermotropism, composed of small- to medium-sized cells that were CD4+, CD82, and CD20+. All of the reported cases of CD20+ MF were diagnosed in male patients, reflecting the previously recognized male predominance of the disease but as well may define a unique clinical feature of CD20+ MF. The largest series to date describing all forms of cutaneous CD20+ T-cell lymphoma was by Rahemtullah et al.20 In this series, 2 of the patients had stable plaque and patch stage MF before developing tumorous lesions manifesting a CD20+ phenotype. Follow-up was only obtained in only 1 of the 2 MF cases. It is unclear if the nodular lesions that subsequently developed represented an evolution in the phenotypic profile that paralleled the more aggressive pattern noted clinically and pathologically. There was no specific mention regarding the Ó 2013 Lippincott Williams & Wilkins
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FIGURE 5. A, There is an extensive staining of the infiltrate for CD20. The deeper component of the infiltrate is without significant staining. In contrast, the CD79a and PAX5 stains showed minimal staining (not illustrated). B, The higher magnification shows the lack of staining of the deeper component of the infiltrate.
phenotypic profile of the earlier classic MF lesions in this case. In our case 3, CD20 expression was observed in the context of tumor stage MF. We did not have access to earlier biopsies to determine whether or not CD20 expression was a feature of tumor progression. In this same series, the authors also described 5 additional men and 2 women with biopsy-proven cutaneous CD20+ T-cell lymphoma.20 In 5 of the patients, there was evidence of nodal disease with subsequent secondary skin involvement, whereas 4 patients had extranodal disease that involved the parotid gland, small intestine, and/or skin at the time of initial presentation. The lymphoma was aggressive in 5 of the cases with death attributable to lymphoma occurring in 4 of the cases within 3 years from the time of diagnosis. An important
conclusion drawn from this article was the correlation of CD20 expression in lesions of cutaneous T-cell lymphoma with a more aggressive clinical course. Although CD20 expression reflects the extent of genotypic aberration that would be expected in a less differentiated T-cell lymphoma, one might also postulate that CD20 expression could be pathogenetically significant. Over the last 2 decades, there has been increasing awareness regarding the existence of populations of T cells expressing CD20 in normal, reactive, or neoplastic settings.24,25 Hultin et al19 first detected circulating peripheral blood T cells that expressed CD20. The level of expression was low and hence the cells were designated as being CD20dim T cells. This rare subset of cells is more likely to be CD8+ and of the gamma
FIGURE 6. A, Colocalization studies assessing for the coexpression of CD3 and CD20 show a number of cells exhibiting expression of CD20 (diaminobenzidene) amid CD3+ (red chromagen) staining cells despite minimal staining for either CD79A or PAX5. B, Colocalization of CD20 (diaminobenzidene) and CD3 (red chromagen) was apparent under higher magnification. The cells exhibiting dual staining have a somewhat rust colored appearance. Ó 2013 Lippincott Williams & Wilkins
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FIGURE 7. A, There is extensive staining of the dermal and intraepidermal lymphocytic infiltrate with CD3. B, The majority of the infiltrate does not express CD7. C, The infiltrate is extensively positive for CD4. D, A few positive staining cells for CD8 are observed. Overall, the CD4 to CD8 ratio is in excess of 5:1.
FIGURE 8. A and B, The double stain for CD3 (red chromagen) and CD20 (diaminobenzidene) shows many cells exhibiting colocalization based on the rust-like staining quality.
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FIGURE 9. A, There is extensive highlighting of the infiltrate for CD3. B, There is a marked reduction in CD7; only 10%–20% of the infiltrate is positive. C, There is marked staining of the infiltrate for CD4. D, There is extensive staining of the infiltrate for CD20.
delta T-cell subset. Additional studies showed that 3% of circulating T cells expressed CD20 weakly and that two-thirds of this cell populace were CD8+. Given the fact that the neoplastic cells in our cases were CD4+ and the expression of CD20 could be very strong would make the espousal incriminating their origin from this dim CD20+ cell populace unlikely. There are mechanisms by which induction of CD20 expression can occur in T cells even though the cells are initially without CD20 expression. Upregulated B-cell CD20 expression has been observed in patients with acute lymphoblastic leukemia following induction treatment with glucocorticoids.26 This is consistent with the synergism observed previously when glucocorticoids and rituximab were administered concurrently to induce antiproliferative and apoptotic activity in non-Hodgkin lymphoma.27 In a similar vein, the mouse CD20 homolog MS4A8A shows glucocorticoid receptor–regulated expression, with restricted expression observed in dimerization-defective glucocorticoid receptor animals.28 It remains an open question whether a similar phenomenon might influence the level of CD20 expression in Ó 2013 Lippincott Williams & Wilkins
subsets of atypical CD4+ T cells of MF exposed to topical glucocorticoid therapy and whether the observed expression might represent de novo transcriptional activation of the MS4A1 locus, or, if preexisting, low-level CD20 expression might be augmented by corticosteroid treatment. CD20 functions in B cells as a Ca2+ channel or a channel regulator that accelerates progression through G1 phase in the cell cycle.29,30 CD20 is a target for serine/threonine phosphorylation on mitogen-stimulated B cells and is associated with many proteins in raft detergent–resistant lipid microdomains contributing to calcium entry. The idea that CD20 could potentially be expressed in T cells is perhaps best exemplified by the expression of MS4a4b, a CD20 homolog in mice, in T helper 1–specific cells.31 It is closely related to the regulation of CD4+ T cell–mediated immune responses, indicative of its role in adaptive immunity. MS4a4B is regulated during primary T-cell activation whereby there is enhanced expression with mitogen concanavalin A stimulation. Induction of CD20 expression with interleukin-2 and mitogen exposure has been described in T cells.19 www.amjdermatopathology.com |
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FIGURE 10. The T-cell receptor studies show a discrete band of clonality in case 1 consistent with a T-cell receptor gene rearrangement. The DNA product was run in 2 separate lanes for reproducibility of results. A clonal T-cell rearrangement is illustrated in lanes 2 and 3 for case 1. A polyclonal pattern was observed for case 2 and is illustrated in lanes 4 and 5. Lane 6 is a monoclonal control.
The expression of PAX5 could not be demonstrated amid T cells expressing CD3 in the 3 cases studied. PAX5 expression has been described in anaplastic large cell lymphoma. The B-cell transcription factor, paired box 5 (PAX5), has been suggested to be a feature of B-cell lineage and hence is positive in the vast majority of B-cell lymphomas.32 There are now emerging reports that describe PAX5 expression in malignant T-cell lymphoproliferative disorders including primary, cutaneous, anaplastic large cell lymphoma. In one recent report, 2 of the 3 patients presenting with CD30+ lymphoproliferative disease died of progressive disease.33 The authors postulated that PAX 5 expression in a T-cell lymphoma could be a feature of a more aggressive phenotype. The authors felt that PAX 5 expression could be analogous to the expression of other B-cell transcription factors such as BOB-1, OCT-2, and BCL-6 in a significant percentage of peripheral T-cell lymphomas.32 In conclusion, in rare instances, the neoplastic cells of MF can express CD20. The expression of CD20 could be indicative that the cell of origin is derived from dim CD20+ B cells, although more likely it is reflective of the aberrant nature of the T-cell populace. One can hypothesize that CD20 is activated in a subset of the infiltrating cells following their malignant conversion and, as a consequence, represent a population with enhanced potential for rapid cell cycle progression and expansion secondary to rapid G1 phase transit.
TABLE 1. Summary of Published CD20+ MF Cases Reference
Age/Gender
Presentation
10
Sen et al
53/M
Lower extremity patches and plaques
Rahemtullah et al20
74/M
Rahemtullah et al20
80/M
History of CTCL; multiple skin lesions (on buttock, thigh, wrist, and eyelid) Two cutaneous plaques on lower extremity
Hagen et al 2013 (This study)
14/M
Plaque on right upper back
Hagen et al 2013 (This study)
80/F
Hagen et al 2013 (This study)
44/M
Nodules and plaques on the head and neck Lesions on lower back
Morphology
Immunophenotype
Dense dermal infiltrate of small/medium lymphocytes with irregular nuclei and with epidermotropism Superficial and deep dermal infiltrate of small and medium/large cells with folded nuclei with epidermotropism
CD2+, CD3+, CD4+, CD5+, CD20+, CD72, CD82, Pax52
Superficial and deep dermal infiltrate of medium to large cells with epidermotropism and folded nuclei Dense band-like infiltrate of small to medium-sized cells with irregular nuclei and with epidermotropism and Pautrier microabscesses Striking folliculotropic large cell lymphocytic infiltrate
CD3+, CD5+, CD4+, CD20+, CD72, CD79a2, Pax52, CD102, CD302, CD562
CD3+, CD5+, CD7+, CD4+, CD20+, CD30+, CD82, CD562, ALK2
CD3+, CD5+, CD4+, CD20+, PD-1 +, CD7dim, CD302
CD4+, CD20+, CD72, CD62L2
Band-like lymphocytic infiltrate with accompanying dermal sclerosis and focal epitheliotropism
CD3+, CD4+, CD20+, CD72, CD62L, PD1
CTCL, cutaneous T-cell lymphomas.
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As has been suggested in a number of the previous reports of CD20+ peripheral T-cell lymphomas, this subpopulation of neoplastic cells might be amenable to targeting by anti-CD20 monoclonal antibody immunotherapy with agents such as rituximab.34 REFERENCES 1. Willemze R, Jaffe ES, Burg G, et al. WHO-EORTC classification for cutaneous lymphomas. Blood. 2005;105:3768–3785. 2. Hwang ST, Janik JE, Jaffe ES, et al. Mycosis fungoides and Sézary syndrome. Lancet. 2008;371:945–957. 3. Loken MR, Shah VO, Dattilio KL, et al. Flow cytometric analysis of human bone marrow. II. Normal B lymphocyte development. Blood. 1987;70:1316–1324. 4. Blakolmer K, Vesely M, Kummer JA, et al. Immunoreactivity of B-cell markers (CD79a, L26) in rare cases of extranodal cytotoxic peripheral T- (NK/T-) cell lymphomas. Mod Pathol. 2000;13:766–772. 5. Buckner CL, Christiansen LR, Bourgeois D, et al. CD20 positive T-cell lymphoma/leukemia: a rare entity with potential diagnostic pitfalls. Ann Clin Lab Sci. 2007;37:263–267. 6. Magro CM, Seilstad KH, Porcu P, et al. Primary CD20+CD10+CD8+ T-cell lymphoma of the skin with IgH and TCR beta gene rearrangement. Am J Clin Pathol. 2006;126:14–22. 7. Mohrmann RL, Arber DA. CD20-positive peripheral T-cell lymphoma: report of a case after nodular sclerosis Hodgkin’s disease and review of the literature. Mod Pathol. 2000;13:1244–1252. 8. Quintanilla-Martinez L, Preffer F, Rubin D, et al. CD20+ T-cell lymphoma. Neoplastic transformation of a normal T-cell subset. Am J Clin Pathol. 1994;102:483–489. 9. Ramsay AD, Smith WJ, Earl HM, et al. T-cell lymphomas in adults: a clinicopathological study of eighteen cases. J Pathol. 1987;152:63–76. 10. Sen F, Kang S, Cangiarella J, et al. CD20 positive mycosis fungoides: a case report. J Cutan Pathol. 2008;35:398–403. 11. Sun T, Akalin A, Rodacker M, et al. CD20 positive T cell lymphoma: is it a real entity? J Clin Pathol. 2004;57:442–444. 12. Takami A, Saito M, Nakao S, et al. CD20-positive T-cell chronic lymphocytic leukaemia. Br J Haematol. 1998;102:1327–1329. 13. Tamayose K, Sato N, Ando J, et al. CD3-negative, CD20-positive T-cell prolymphocytic leukemia: case report and review of the literature. Am J Hematol. 2002;1:331–335. 14. Kitamura A, Yamashita Y, Mori N. CD20-positive cytotoxic T cell lymphoma: report of two cases and review of the literature. J Clin Exp Hematop. 2005;45:45–50. 15. Yao X, Teruya-Feldstein J, Raffeld M, et al. Peripheral T-cell lymphoma with aberrant expression of CD79a and CD20: a diagnostic pitfall. Mod Pathol. 2001;14:105–110. 16. Xu X, Broome EH, Rashidi HH, et al. CD20dim-positive T-cell large granular lymphocytic leukemia in a patient with concurrent hairy cell leukemia and plasma cell myeloma. Int J Clin Exp Pathol. 2010;3: 798–807. 17. Yokose N, Ogata K, Sugisaki Y, et al. CD20-positive T cell leukemia/ lymphoma: case report and review of the literature. Ann Hematol. 2001; 80:372–375.
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18. Balmer NN, Hughey L, Busam KJ, et al. Primary cutaneous peripheral T-cell lymphoma with aberrant coexpression of CD20: case report and review of the literature. Am J Dermatopathol. 2009;31: 187–192. 19. Hultin LE, Hausner MA, Hultin PM, et al. CD20 (pan–B cell) antigen is expressed at a low level on a subpopulation of human T-lymphocytes. Cytometry. 1993;14:196–204. 20. Rahemtullah A, Longtine JA, Harris NL, et al. CD20+ T-cell lymphoma: clinicopathologic analysis of 9 cases and a review of the literature. Am J Surg Pathol. 2008;32:1593–1607. 21. van Dongen JJ, Langerak AW, Brüggemann M, et al. Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936. Leukemia. 2003;17:2257–2317. 22. Evans PA, Pott Ch, Groenen PJ, et al. Significantly improved PCR-based clonality testing in B-cell malignancies by use of multiple immunoglobulin gene targets. Report of the BIOMED-2 Concerted Action BHM4CT98-3936. Leukemia. 2007;21:207–214. 23. Yazganoglu KD, Topkarci Z, Buyukbabani N, et al. Childhood mycosis fungoides: a report of 20 cases from Turkey. J Eur Acad Dermatol Venereol. 2013;27:295–300. 24. Algino KM, Thomason RW, King DE, et al. CD20 (pan-B cell antigen) expression on bone marrow-derived T cells. Am J Clin Pathol. 1996;106: 78–81. 25. Warzynski MJ, Graham DM, Axtell RA, et al. Low level CD20 expression on T cell malignancies. Cytometry. 1994;18:88–92. 26. Dworzak MN, Schumich A, Printz D, et al. CD20 up-regulation in pediatric B-cell precursor acute lymphoblastic leukemia during induction treatment: setting the stage for anti-CD20 directed immunotherapy. Blood. 2008;112:3982–3988. 27. Rose AL, Smith BE, Maloney DG. Glucocorticoids and rituximab in vitro: synergistic direct antiproliferative and apoptotic effects. Blood. 2002;100:1765–1773. 28. Schmieder A, Schledzewski K, Michel J, et al. Synergistic activation by p38MAPK and glucocorticoid signaling mediates induction of M2-like tumor-associated macrophages expressing the novel CD20 homolog MS4A8A. Int J Cancer. 2011;129:122–132. 29. Bubien JK, Zhou LJ, Bell PD, et al. Transfection of the CD20 cell surface molecule into ectopic cell types generates a Ca2+ conductance found constitutively in B lymphocytes. J Cell Biol. 1993;121:1121–1132. 30. Kanzaki M, Shibata H, Mogami H, et al. Expression of calcium-permeable cation channel CD20 accelerates progression through the G1 phase in Balb/c 3T3 cells. J Biol Chem. 1995;270:13099–13104. 31. Xu H, Yan Y, Williams MS, et al. MS4a4B, a CD20 homologue in T cells, inhibits T cell propagation by modulation of cell cycle. PLoS One. 2010;5:e13780. 32. Bougel S, Renaud S, Braunschweig R, et al. PAX5 activates the transcription of the human telomerase reverse transcriptase gene in B cells. J Pathol. 2010;220:87–96. 33. Hagiwara M, Tomita A, Takata K, et al. Primary cutaneous CD30 positive T-cell lymphoproliferative disorders with aberrant expression of PAX5: report of three cases. Pathol Int. 2012;62:264–270. 34. Taylor RP, Lindorfer MA. Immunotherapeutic mechanisms of anti-CD20 monoclonal antibodies. Curr Opin Immunol. 2008;20:444–449.
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CD20+ Mycosis Fungoides: A Report of Three Cases and Review of the Literature Joshua W. Hagen, PhD, MD,* Jochen T. Schaefer, MD,† and Cynthia M. Magro, MD‡
Abstract: Mycosis fungoides (MF) is the most common of the family of cutaneous T-cell lymphomas, accounting for 65% of all cases of cutaneous T-cell lymphomas. The classic phenotypic profile is one defined by CD4+ T cells showing a reduction in the expression of CD7 and CD62L. There are 3 previous reports describing CD20 expression in MF. The cell surface antigen CD20 is a transmembrane glycosylated phosphoprotein expressed in the early stages of B-cell development before differentiation into plasma cells. Two male patients, aged 14 and 44 years, presented with persistent truncal plaques up to 8 cm of 1 and 4 years duration, respectively. A third patient, an 80-year-old female, presented with a 1-year history of progressive nodules involving the head and neck area. Cases 1 and 2 both responded to topical treatment modalities. The biopsies in cases 1 and 2 showed features typical of plaque stage MF, whereas case 3 was compatible with follicular MF with tumor stage transformation. Phenotypically, the aberrant cell populace demonstrated a CD4+, CD72, and CD62L2 phenotype; at variance with classic MF was the expression of CD20. Although there were a few PAX5-positive staining cells, definitive colocalization studies were negative. Other B-cell markers and heavy chain immunoglobulin rearrangement were not detected. There are a growing number of reports describing T-cell lymphomas and leukemias with CD20 expression. Of the 6 CD20+ MF cases reported in the literature to date, 3 have been associated with a more aggressive clinical course; all but one case have occurred in males. Key Words: CD20, T-cell lymphoma, mycosis fungoides (Am J Dermatopathol 2013;35:833–841)
INTRODUCTION Mycosis fungoides (MF) is the most common of the family of cutaneous T-cell lymphomas, accounting for up to 65% of all cases of cutaneous T-cell lymphomas.1 It is considered an indolent lymphoproliferative disorder most commonly presenting with pruritic plaques and patches involving photoprotected skin. MF is approximately twice as common in men as in women and shows racial predilection, with From the *Department of Medical Education, Weill Medical College of Cornell University, New York, NY; †Departments of Dermatology and Dermatopathology University of Connecticut Dermatology Associates, University of Connecticut Health Center, Farmington, CT; and ‡Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, New York, NY. The authors declare no conflicts of interest. Reprints: Cynthia M. Magro, MD, Department of Pathology and Laboratory Medicine, Weill Medical College of Cornell University, Box 58, Room F-309, 1300 York Avenue, New York, NY 10065 (e-mail: cym2003@ med.cornell.edu). © 2013 Lippincott Williams & Wilkins
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blacks affected at almost double the frequency noted in non-Hispanic whites. The majority of cases are diagnosed in the fifth and sixth decades of life, whereas adolescents are only rarely affected. The diagnosis of MF relies heavily on both clinical presentation and histopathology, that latter of which is classically characterized by a superficial epidermotropic infiltration of neoplastic CD4+ T cells.2 The cell surface antigen CD20 is a transmembrane glycosylated phosphoprotein encoded by the MS4A1 gene and expressed in the early stages of B-cell development before differentiation into plasma cells.3 It is widely believed that CD20 represents a relatively specific marker of B-cell differentiation, although there are a growing number of reports describing T-cell lymphomas and leukemias with CD20 expression detected by antibodies directed against a variety of CD20 epitopes.4–18 In addition, CD20 is expressed on a small population of reactive T cells where the staining pattern is weak compared with CD20 expression in B cells.19 The literature reveals only 3 reports observing CD20 expression in the context of MF. One of the first reported cases of CD20+ MF was presented in the context of rare peripheral T-cell lymphomas with CD20 expression, which the authors categorized as MF.10 This first case report was soon followed by an additional case series detailing a spectrum of CD20+ T-cell lymphomas that included 2 individuals with a clinical presentation and morphology meeting diagnostic criteria for MF.20 We report 3 additional patients showing pathology consistent with CD20+ MF, expanding the number of reported cases of this extremely rare immunophenotypic variant. The pathogenetic basis of CD20 expression in cutaneous lesions of MF is explored.
MATERIALS AND METHODS Phenotypic Studies Tissue sections of 5-mm, formalin-fixed paraffinembedded tissues were cut on positively charged slides. The slides were then treated with xylene and 95% alcohol and rehydrated before staining with antibody. In each case, comprehensive phenotypic studies were conducted including Beta F1, CD2, CD3, CD4, CD5, CD7, CD8, CD20, and CD62L. The methodology has been previously described. In addition in both cases, colocalization studies were conducted to assess for dual expression of CD20 and CD3 and that of PAX5 and CD3. The double staining for CD3/CD20 was carried out by using a 2-step immunohistochemistry procedure. The sections were incubated for 30 minutes and stained with each antibody sequentially, first CD3 and then CD20, using the commercially available Leica Biosystems www.amjdermatopathology.com |
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and following the protocol. The CD3 antibody was incubated at a dilution of 1:100, and the CD20 antibody was undiluted and ready to use. In each of the colocalization studies, a red chromagen was used for CD20, whereas the T-cell immunostain used a daminobenzidine technique. In regard to the PAX5 colocalization studies, the same procedure was carried out except a red chromagen was used to detect CD3 and a diaminobenzidene stain was used for visualization of PAX5.
Molecular Studies DNA was extracted from formalin-fixed paraffinembedded tissue. A polymerase chain reaction (PCR) reaction to assess the presence of immunoglobulin heavy chain gene rearrangements was performed using FR3 and JH primers. The products of these reactions were analyzed by polyacrylamide gel electrophoresis. To increase the sensitivity of clonality detection in lymphoma, additional PCR reactions were performed to assess the common rearrangements of immunoglobulin kappa light gene using the BIOMED2 assays. Two multiplex PCR reactions were conducted using six sets of primers in each reaction that are hybridized to the immunoglobulin kappa light gene locus.21,22 PCR products were analyzed by polyacrylamide gel electrophoresis.
CASE REPORTS Case 1 A 14-year-old boy presented with a solitary, discolored erythematous lesion on the right shoulder that had been present for 1 year without significant change in size or appearance. Patientinitiated empiric home therapy with topical cortisone cream was reported to result in some partial resolution of the lesion at least in regard to the extent of dyschromia. There was no history of skin cancer for the patient or his family, and the patient was otherwise well. Examination revealed a 3-cm erythematous patch with central
clearing on the right upper back. Two 4-mm punch biopsies were taken for further analysis.
Case 2 A 44-year-old man presented in 2011 with multiple erythematous patches and plaques up to 6–8 cm in diameter, predominantly in the lower back and sacral area. The patient first noticed skin lesions in 2006. The lesions have had a waxing and waning clinical course. Topical steroid therapy was without significant clinical effect. The patient’s medical history was significant for arterial hypertension, which has been treated with nebivolol. The family history was negative for hematologic disorders.
Case 3 The patient was an 80-year-old female who presented with a history of a recurrent rash largely localized to the face, chest, and back. Her medical history was remarkable for hypertension and hyperlipidemia. Her medication history included allopurinol, Metoprolol, nifedipine, simvastatin, and hydrochlorothiazide. Physical examination revealed crusted nodules on the neck and posterior right ear.
Light Microscopic Findings The biopsies in cases 1 and 2 appeared similar, showing a constellation of findings typical for plaque stage MF (Figs. 1, 2). In both cases, there was a superficial mononuclear cell infiltrate that assumed a nondestructive band-like lichenoid pattern. The infiltrate was of lesser intensity in case 2 compared with case 1 and was associated with dermal sclerosis (Fig. 2A). There was basilar and parabasilar colonization by atypical cerebriform lymphocytes (Figs. 1B, 2B). A greater extent of intraepidermal lymphoid atypia was noted compared with the lymphocytes within the dermis. In case 1, the inflammatory infiltrate also exhibited folliculocentricity. In case 2, there was an element of attendant basilar vacuolar change with incipient dyskeratosis (Fig. 2A, B). Rare Langerhans cell rich vesicles imparting an almost eczematoid morphology to the process was also noted in case 2. The lymphocytes were small and cerebriform in quality; the atypicality was best appreciated under oil examination. In case 3, there was a striking large cell infiltrate of
FIGURE 1. A, Case 1 shows a band-like lymphocytic infiltrate lying in close apposition to the long axis of the epidermis. A narrow grenz zone separates the infiltrate from the overlying epidermis. There is a component of laminated sclerosis. Significant deeper seated extension of the infiltrate is not seen. B, There is colonization of the epidermis by lymphocytes unaccompanied by significant destructive epithelial changes. Lymphocytes extend into the mid and upper spinous layers of the epidermis. The lymphocytes are hyperchromatic and exhibit cerebriform morphology.
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FIGURE 2. A, In case 2, the biopsy shows a band-like lymphocytic infiltrate lying in close apposition to the epidermis. There is attendant dermal sclerosis. Focal epitheliotropism is present unaccompanied by any obvious destructive epithelial changes. B, A higher magnification shows a passive pattern of lymphocyte migration into the epidermis with dominant localization to involve the basal layer. There is a lack of epithelial destruction. cerebriform and immunoblastic appearing lymphocytes involving the superficial half of the dermis. The infiltrate was largely nonepidermotropic, although there were small foci of epidermotropism (Fig. 3). Prominent involvement of the adventitial dermis of the hair follicle along with marked infiltration of the outer root sheath epithelium was observed. There were also admixed plasma cells present throughout the depths of the biopsy.
Phenotypic Studies In case 1, there was extensive highlighting of the infiltrate for CD3 and CD5 (Fig. 4A). However, there was a marked reduction of CD7 with only 30% of the intraepidermal and dermal lymphocytes exhibiting immunoreactivity (Fig. 4B). The CD4 to CD8 ratio was very high (Figs. 4C, D). CD30 studies were negative. A CD20 preparation showed extensive positivity of the dermal infiltrate; a cytoplasmic membrane pattern of staining was observed; the
staining intensity was strong (Fig. 5). A combined CD3 and CD20 stain appeared to show colocalization of several neoplastic T cells with CD20 (Fig. 6). A curious finding was a pattern of differential staining with extensive and prominent CD20 staining of lymphocytes closest to the epidermis (Fig. 5A). The lower half of the infiltrate showed an absence of positivity for CD20. The dual CD3/ PAX5 stain did not show any colocalization amid the lymphocytes within the dermis. With regard to case 2, the infiltrate was phenotypically aberrant by virtue of the high CD4 to CD8 ratio in excess of 5:1 and the selective loss of CD7 especially amid the more atypical lymphocytes within the epidermis and dermis with a greater degree of diminution of expression within the intraepidermal compartment (Figs. 7A–D). Of the infiltrate, 30%–40% was positive for CD62L, whereas the intraepidermal lymphocytes were essentially negative for CD62L. A combined CD20/CD3 stain showed colocalization of dermal and intraepidermal atypical lymphocytes for CD20 and CD3, indicative of a dual expression of CD3 and CD20 (Figs. 8A, B). Approximately 30% of the intraepidermal and dermal lymphocytic infiltrate showed dual staining for CD20 and CD3. The staining intensity for CD20 was moderate to marked in degrees, exhibiting a diffuse granular cytoplasmic membrane pattern of immunoreactivity. In case 2, there was also focal staining of intraepidermal and dermal T cells for PAX5, although the number of cells showing positive staining was less than that observed for CD20. However, the CD20 and PAX5 colocalization studies were essentially negative. With respect to case 3, the infiltrate was extensively highlighted by CD2, CD3, and Beta F1 (Fig. 9A). There was a marked reduction in the expression of both CD7 and CD5 (Fig. 9B). The infiltrate was almost exclusively of the CD4 subset (Fig. 9C). There was almost an equivalent pattern of staining for CD20 as that noted for CD3 (Fig. 9D). The CD3+ cell populace showed colocalization with CD20. The staining intensity for CD20 was strong and similar to that observed for CD2, CD3, and CD4 qualitatively and quantitatively.
Molecular Studies FIGURE 3. The biopsy shows a striking folliculotropic lymphocytic infiltrate. There is marked infiltration of the adventitial dermis and outer root sheath epithelium by lymphocytes. Ó 2013 Lippincott Williams & Wilkins
T-cell receptor studies were performed on all 3 cases. Cases 1 and 3 showed a monoclonal rearrangement, whereas a polyclonal pattern was noted for case 2. Illustrations of the monoclonal and polyclonal patterns for cases 1 and 2 are provided in Figure 10. www.amjdermatopathology.com |
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FIGURE 4. A, The infiltrate is highlighted by CD3. B, There is a marked reduction in the expression of CD7. Eighty percent of the infiltrate is without significant staining for CD7. C, There is marked positivity of the infiltrate for CD4. D, In contrast, the infiltrate shows minimal staining for CD8. Heavy chain immunoglobulin gene rearrangements were not uncovered in case 1. They were not assessed in the other 2 cases.
DISCUSSION We have presented 3 cases of MF that represent an interesting departure from the typical diagnostic picture for MF by virtue of the atypical expression of the pan B-cell marker CD20. In 2 cases, both patients were males exhibiting a stable nonprogressive clinical course. One patient was an elderly female with tumor stage follicular MF. In the one young adolescent male, the presentation was in the context of unilesional MF. A recent series addressing pediatric MF found a higher incidence of unusual variants of MF including unilesional, hypopigmented, and purpuric MF. The unilesional cases accounted for 20% of the reported cases in this particular series.23 In our case, over and above the aberrant phenotype, the identification of T-cell clonality provided additional corroborative evidence regarding the categorization as MF.
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An extensive search of the literature revealed only 3 previous cases of CD20+ MF (Table 1). The first reported case by Sen et al10 reported a 53-year-old male with lower extremity patches and plaques showing dense dermal lymphocytic infiltrates exhibiting epidermotropism, composed of small- to medium-sized cells that were CD4+, CD82, and CD20+. All of the reported cases of CD20+ MF were diagnosed in male patients, reflecting the previously recognized male predominance of the disease but as well may define a unique clinical feature of CD20+ MF. The largest series to date describing all forms of cutaneous CD20+ T-cell lymphoma was by Rahemtullah et al.20 In this series, 2 of the patients had stable plaque and patch stage MF before developing tumorous lesions manifesting a CD20+ phenotype. Follow-up was only obtained in only 1 of the 2 MF cases. It is unclear if the nodular lesions that subsequently developed represented an evolution in the phenotypic profile that paralleled the more aggressive pattern noted clinically and pathologically. There was no specific mention regarding the Ó 2013 Lippincott Williams & Wilkins
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FIGURE 5. A, There is an extensive staining of the infiltrate for CD20. The deeper component of the infiltrate is without significant staining. In contrast, the CD79a and PAX5 stains showed minimal staining (not illustrated). B, The higher magnification shows the lack of staining of the deeper component of the infiltrate.
phenotypic profile of the earlier classic MF lesions in this case. In our case 3, CD20 expression was observed in the context of tumor stage MF. We did not have access to earlier biopsies to determine whether or not CD20 expression was a feature of tumor progression. In this same series, the authors also described 5 additional men and 2 women with biopsy-proven cutaneous CD20+ T-cell lymphoma.20 In 5 of the patients, there was evidence of nodal disease with subsequent secondary skin involvement, whereas 4 patients had extranodal disease that involved the parotid gland, small intestine, and/or skin at the time of initial presentation. The lymphoma was aggressive in 5 of the cases with death attributable to lymphoma occurring in 4 of the cases within 3 years from the time of diagnosis. An important
conclusion drawn from this article was the correlation of CD20 expression in lesions of cutaneous T-cell lymphoma with a more aggressive clinical course. Although CD20 expression reflects the extent of genotypic aberration that would be expected in a less differentiated T-cell lymphoma, one might also postulate that CD20 expression could be pathogenetically significant. Over the last 2 decades, there has been increasing awareness regarding the existence of populations of T cells expressing CD20 in normal, reactive, or neoplastic settings.24,25 Hultin et al19 first detected circulating peripheral blood T cells that expressed CD20. The level of expression was low and hence the cells were designated as being CD20dim T cells. This rare subset of cells is more likely to be CD8+ and of the gamma
FIGURE 6. A, Colocalization studies assessing for the coexpression of CD3 and CD20 show a number of cells exhibiting expression of CD20 (diaminobenzidene) amid CD3+ (red chromagen) staining cells despite minimal staining for either CD79A or PAX5. B, Colocalization of CD20 (diaminobenzidene) and CD3 (red chromagen) was apparent under higher magnification. The cells exhibiting dual staining have a somewhat rust colored appearance. Ó 2013 Lippincott Williams & Wilkins
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FIGURE 7. A, There is extensive staining of the dermal and intraepidermal lymphocytic infiltrate with CD3. B, The majority of the infiltrate does not express CD7. C, The infiltrate is extensively positive for CD4. D, A few positive staining cells for CD8 are observed. Overall, the CD4 to CD8 ratio is in excess of 5:1.
FIGURE 8. A and B, The double stain for CD3 (red chromagen) and CD20 (diaminobenzidene) shows many cells exhibiting colocalization based on the rust-like staining quality.
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FIGURE 9. A, There is extensive highlighting of the infiltrate for CD3. B, There is a marked reduction in CD7; only 10%–20% of the infiltrate is positive. C, There is marked staining of the infiltrate for CD4. D, There is extensive staining of the infiltrate for CD20.
delta T-cell subset. Additional studies showed that 3% of circulating T cells expressed CD20 weakly and that two-thirds of this cell populace were CD8+. Given the fact that the neoplastic cells in our cases were CD4+ and the expression of CD20 could be very strong would make the espousal incriminating their origin from this dim CD20+ cell populace unlikely. There are mechanisms by which induction of CD20 expression can occur in T cells even though the cells are initially without CD20 expression. Upregulated B-cell CD20 expression has been observed in patients with acute lymphoblastic leukemia following induction treatment with glucocorticoids.26 This is consistent with the synergism observed previously when glucocorticoids and rituximab were administered concurrently to induce antiproliferative and apoptotic activity in non-Hodgkin lymphoma.27 In a similar vein, the mouse CD20 homolog MS4A8A shows glucocorticoid receptor–regulated expression, with restricted expression observed in dimerization-defective glucocorticoid receptor animals.28 It remains an open question whether a similar phenomenon might influence the level of CD20 expression in Ó 2013 Lippincott Williams & Wilkins
subsets of atypical CD4+ T cells of MF exposed to topical glucocorticoid therapy and whether the observed expression might represent de novo transcriptional activation of the MS4A1 locus, or, if preexisting, low-level CD20 expression might be augmented by corticosteroid treatment. CD20 functions in B cells as a Ca2+ channel or a channel regulator that accelerates progression through G1 phase in the cell cycle.29,30 CD20 is a target for serine/threonine phosphorylation on mitogen-stimulated B cells and is associated with many proteins in raft detergent–resistant lipid microdomains contributing to calcium entry. The idea that CD20 could potentially be expressed in T cells is perhaps best exemplified by the expression of MS4a4b, a CD20 homolog in mice, in T helper 1–specific cells.31 It is closely related to the regulation of CD4+ T cell–mediated immune responses, indicative of its role in adaptive immunity. MS4a4B is regulated during primary T-cell activation whereby there is enhanced expression with mitogen concanavalin A stimulation. Induction of CD20 expression with interleukin-2 and mitogen exposure has been described in T cells.19 www.amjdermatopathology.com |
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FIGURE 10. The T-cell receptor studies show a discrete band of clonality in case 1 consistent with a T-cell receptor gene rearrangement. The DNA product was run in 2 separate lanes for reproducibility of results. A clonal T-cell rearrangement is illustrated in lanes 2 and 3 for case 1. A polyclonal pattern was observed for case 2 and is illustrated in lanes 4 and 5. Lane 6 is a monoclonal control.
The expression of PAX5 could not be demonstrated amid T cells expressing CD3 in the 3 cases studied. PAX5 expression has been described in anaplastic large cell lymphoma. The B-cell transcription factor, paired box 5 (PAX5), has been suggested to be a feature of B-cell lineage and hence is positive in the vast majority of B-cell lymphomas.32 There are now emerging reports that describe PAX5 expression in malignant T-cell lymphoproliferative disorders including primary, cutaneous, anaplastic large cell lymphoma. In one recent report, 2 of the 3 patients presenting with CD30+ lymphoproliferative disease died of progressive disease.33 The authors postulated that PAX 5 expression in a T-cell lymphoma could be a feature of a more aggressive phenotype. The authors felt that PAX 5 expression could be analogous to the expression of other B-cell transcription factors such as BOB-1, OCT-2, and BCL-6 in a significant percentage of peripheral T-cell lymphomas.32 In conclusion, in rare instances, the neoplastic cells of MF can express CD20. The expression of CD20 could be indicative that the cell of origin is derived from dim CD20+ B cells, although more likely it is reflective of the aberrant nature of the T-cell populace. One can hypothesize that CD20 is activated in a subset of the infiltrating cells following their malignant conversion and, as a consequence, represent a population with enhanced potential for rapid cell cycle progression and expansion secondary to rapid G1 phase transit.
TABLE 1. Summary of Published CD20+ MF Cases Reference
Age/Gender
Presentation
10
Sen et al
53/M
Lower extremity patches and plaques
Rahemtullah et al20
74/M
Rahemtullah et al20
80/M
History of CTCL; multiple skin lesions (on buttock, thigh, wrist, and eyelid) Two cutaneous plaques on lower extremity
Hagen et al 2013 (This study)
14/M
Plaque on right upper back
Hagen et al 2013 (This study)
80/F
Hagen et al 2013 (This study)
44/M
Nodules and plaques on the head and neck Lesions on lower back
Morphology
Immunophenotype
Dense dermal infiltrate of small/medium lymphocytes with irregular nuclei and with epidermotropism Superficial and deep dermal infiltrate of small and medium/large cells with folded nuclei with epidermotropism
CD2+, CD3+, CD4+, CD5+, CD20+, CD72, CD82, Pax52
Superficial and deep dermal infiltrate of medium to large cells with epidermotropism and folded nuclei Dense band-like infiltrate of small to medium-sized cells with irregular nuclei and with epidermotropism and Pautrier microabscesses Striking folliculotropic large cell lymphocytic infiltrate
CD3+, CD5+, CD4+, CD20+, CD72, CD79a2, Pax52, CD102, CD302, CD562
CD3+, CD5+, CD7+, CD4+, CD20+, CD30+, CD82, CD562, ALK2
CD3+, CD5+, CD4+, CD20+, PD-1 +, CD7dim, CD302
CD4+, CD20+, CD72, CD62L2
Band-like lymphocytic infiltrate with accompanying dermal sclerosis and focal epitheliotropism
CD3+, CD4+, CD20+, CD72, CD62L, PD1
CTCL, cutaneous T-cell lymphomas.
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As has been suggested in a number of the previous reports of CD20+ peripheral T-cell lymphomas, this subpopulation of neoplastic cells might be amenable to targeting by anti-CD20 monoclonal antibody immunotherapy with agents such as rituximab.34 REFERENCES 1. Willemze R, Jaffe ES, Burg G, et al. WHO-EORTC classification for cutaneous lymphomas. Blood. 2005;105:3768–3785. 2. Hwang ST, Janik JE, Jaffe ES, et al. Mycosis fungoides and Sézary syndrome. Lancet. 2008;371:945–957. 3. Loken MR, Shah VO, Dattilio KL, et al. Flow cytometric analysis of human bone marrow. II. Normal B lymphocyte development. Blood. 1987;70:1316–1324. 4. Blakolmer K, Vesely M, Kummer JA, et al. Immunoreactivity of B-cell markers (CD79a, L26) in rare cases of extranodal cytotoxic peripheral T- (NK/T-) cell lymphomas. Mod Pathol. 2000;13:766–772. 5. Buckner CL, Christiansen LR, Bourgeois D, et al. CD20 positive T-cell lymphoma/leukemia: a rare entity with potential diagnostic pitfalls. Ann Clin Lab Sci. 2007;37:263–267. 6. Magro CM, Seilstad KH, Porcu P, et al. Primary CD20+CD10+CD8+ T-cell lymphoma of the skin with IgH and TCR beta gene rearrangement. Am J Clin Pathol. 2006;126:14–22. 7. Mohrmann RL, Arber DA. CD20-positive peripheral T-cell lymphoma: report of a case after nodular sclerosis Hodgkin’s disease and review of the literature. Mod Pathol. 2000;13:1244–1252. 8. Quintanilla-Martinez L, Preffer F, Rubin D, et al. CD20+ T-cell lymphoma. Neoplastic transformation of a normal T-cell subset. Am J Clin Pathol. 1994;102:483–489. 9. Ramsay AD, Smith WJ, Earl HM, et al. T-cell lymphomas in adults: a clinicopathological study of eighteen cases. J Pathol. 1987;152:63–76. 10. Sen F, Kang S, Cangiarella J, et al. CD20 positive mycosis fungoides: a case report. J Cutan Pathol. 2008;35:398–403. 11. Sun T, Akalin A, Rodacker M, et al. CD20 positive T cell lymphoma: is it a real entity? J Clin Pathol. 2004;57:442–444. 12. Takami A, Saito M, Nakao S, et al. CD20-positive T-cell chronic lymphocytic leukaemia. Br J Haematol. 1998;102:1327–1329. 13. Tamayose K, Sato N, Ando J, et al. CD3-negative, CD20-positive T-cell prolymphocytic leukemia: case report and review of the literature. Am J Hematol. 2002;1:331–335. 14. Kitamura A, Yamashita Y, Mori N. CD20-positive cytotoxic T cell lymphoma: report of two cases and review of the literature. J Clin Exp Hematop. 2005;45:45–50. 15. Yao X, Teruya-Feldstein J, Raffeld M, et al. Peripheral T-cell lymphoma with aberrant expression of CD79a and CD20: a diagnostic pitfall. Mod Pathol. 2001;14:105–110. 16. Xu X, Broome EH, Rashidi HH, et al. CD20dim-positive T-cell large granular lymphocytic leukemia in a patient with concurrent hairy cell leukemia and plasma cell myeloma. Int J Clin Exp Pathol. 2010;3: 798–807. 17. Yokose N, Ogata K, Sugisaki Y, et al. CD20-positive T cell leukemia/ lymphoma: case report and review of the literature. Ann Hematol. 2001; 80:372–375.
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