© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
J Cutan Pathol 2014: 41: 293–296 doi: 10.1111/cup.12272 John Wiley & Sons. Printed in Singapore
Journal of Cutaneous Pathology
Punctate pemphigus: an underreported direct immunofluorescence pattern Intercellular epidermal deposition of immunoglobulin G (IgG) in a continuous net-like or ‘chicken wire’ pattern is a well-described and diagnostic finding in direct immunofluorescence (DIF) studies of pemphigus. In our experience, punctate or dot-like intercellular deposition of IgG can also be seen in cases of pemphigus but has received little attention in the literature. We describe a series of DIF specimens showing intercellular deposition of IgG in continuous and/or punctate patterns, which occurred with equal frequency in pemphigus vulgaris and pemphigus foliaceus. This series highlights the punctate or dot-like pattern of intercellular IgG deposition in DIF studies of pemphigus, reviews potential mechanisms and calls attention to this potentially under-recognized phenomenon.
Christine J. Ko and Jennifer M. McNiff
Keywords: desmosome, dot-like, immunofluorescence, pemphigus, punctate
Associate Prof. Christine Ko, MD Dermatology and Pathology, Yale University, New Haven, CT, USA Tel: +1 203 785 4094 Fax: 203-785-6869 e-mail: [email protected]
Ko CJ, McNiff JM. Punctate pemphigus: an underreported direct immunofluorescence pattern. J Cutan Pathol 2014; 41: 293–296. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Intercellular continuous net-like deposition of immunoglobulin G (IgG) and C3 in the epidermis is well-recognized and diagnostic of pemphigus.1 – 5 In practice, we have noted that some specimens have an interrupted, punctate intercellular pattern of immunoreactant deposition corresponding to cases of pemphigus with otherwise typical clinical and histopathological findings. This punctate pattern is only briefly mentioned in a few textbooks1 and is largely overlooked in many standard dermatopathology references.2,5 The identification of intercellular dot-like positivity by direct immunofluorescence (DIF) studies presumably reflects localization of desmogleins 1 and 3 (the antigens of pemphigus) to desmosomes.6,7 This punctate pattern may reflect the exact location of the target desmoglein antigens within desmosomes7 and/or correspond to older lesions showing aggregation of desmosomes1 due to
Dermatology and Pathology, Yale University, New Haven, CT, USA
Accepted for publication November 20, 2013
well-developed acantholysis. This report describes the finding of punctate intercellular deposition of IgG in pemphigus in greater detail, and reviews potential implications of this observation. Materials and methods We searched our laboratory database for all DIF cases showing an intercellular pattern of deposition of IgG and/or C3 in cases accessioned from December 15, 2004 to October 3, 2013. Immunofluorescence patterns were assessed by retrospective review of photomicrographs illustrating positive staining where available. In addition, separate companion biopsies, typically representing lesional tissue processed and stained with hematoxylin and eosin, were reviewed for subcorneal and suprabasilar acantholysis, subcorneal and intraepidermal eosinophils and neutrophils, and eosinophilic spongiosis in 24 cases.
293
Ko & McNiff Table 1. Pattern of immunoglobulin G (IgG) deposition on direct immunofluorescence (DIF) for 37 cases of pemphigus Pattern
Number of Final diagnosis cases (number of cases)*
Continuous [net-like (lace-like)]
14
Continuous and punctate
13
Punctate alone
10
Pemphigus vulgaris (3) Pemphigus foliaceus (1) Pemphigus, NOS (10) Pemphigus vulgaris (6) Pemphigus foliaceus (3) Pemphigus, NOS (4) Pemphigus vulgaris (4) Pemphigus foliaceus (2) Pemphigus, NOS (4)
Table 2. Hematoxylin and eosin findings and corresponding diagnoses in 24 cases Hematoxylin and eosin characteristic Suprabasilar acantholysis Subcorneal acantholysis Subcorneal neutrophils/pustules Eosinophilic spongiosis
Final diagnosis*
Number of cases
Pemphigus vulgaris
13
Pemphigus foliaceus Pemphigus foliaceus, favored
6 1
Pemphigus, NOS
4
NOS, not otherwise specified. *After correlation with clinical and hematoxylin/eosin findings.
*After correlation with clinical and hematoxylin/eosin findings in 24 cases.
Fig. 1. Pemphigus. Direct immunofluorescence staining for immunoglobulin G (IgG) shows irregular intercellular punctate dots of variable size.
For the majority of cases, frozen hematoxylin and eosin-stained sections of perilesional tissue submitted for immunofluorescence testing were available for review. DIF testing was performed using a Dako Autostainer Plus (Dako, Carpinteria, CA, USA) with frozen sections of patient skin biopsies cut at 6 μ, labeled with fluorescein-conjugated goat anti-human antibodies in phosphate buffered saline (PBS) with 0.05% Tween 20 surfactant, directed against IgG (dilution 1 : 75), C3 (dilution 1 : 75), IgM (dilution 1 : 50), IgA (dilution 1 : 25) and fibrinogen (dilution 1 : 100) (MP Biomedicals, Solon, OH, USA). Appropriate controls were run in parallel. Results Over approximately 9 years, there were 66 DIF cases consistent with pemphigus, which were characterized by intercellular IgG and/or C3 deposits. The vast majority had deposition of both IgG and C3, with 10 cases having IgG without C3. Thirty-seven of these cases had high-resolution photomicrographs of DIF with IgG available for review and results are shown in Table 1. The punctate pattern was sometimes composed of uniform intercellular dots and sometimes dots of irregular size (Fig. 1). Hematoxylin and
294
Fig. 2. Pemphigus. Direct immunofluorescence staining for immunoglobulin G (IgG) shows a combined pattern, with uniform, punctate intercellular dots in the lower half of the epidermis and a continuous, net-like intercellular pattern of IgG deposition in the upper half of the epidermis.
Fig. 3. Pemphigus. Direct immunofluorescence staining shows a relatively continuous or net-like pattern of immunoglobulin G (IgG) deposition. On close inspection, particularly in the basal layer, there are a few, scattered intercellular dots.
eosin findings from separate lesional biopsies are documented in Table 2. In cases with both dot-like and continuous patterns, the continuous net-like pattern was often most evident in the superficial epidermis, whereas the dot-like pattern was more prevalent in the lower one-half of the epidermis (Fig. 2). In a few of the cases classified as having a continuous pattern, on close inspection, a few dots were sometimes present, especially in the basal layers (Fig. 3).
Punctate pemphigus Table 3. Degree of acantholysis and inflammation in hematoxylin/eosin-stained frozen section slides accompanying direct immunofluorescence (DIF) specimens
Vesiculation from acantholysis Subtle focal acantholysis No acantholysis Dermal inflammation
Punctate pattern
Continuous pattern
Continuous and punctate pattern
6/7 (86%)
5/12 (42%)
4/10 (40%)
0/10 (0%)
5/12 (42%)
5/10 (50%)
1/7 (14%) 7/7 (100%)
2/12 (10%) 2/12 (83%)
1/10 (10%) 9/10 (90%)
The duration of disease was known in only four cases. One case with a continuous pattern of deposition was from a patient whose initial diagnosis of pemphigus vulgaris was 18 years prior. One case with a dot-like pattern of deposition had documented pemphigus vulgaris for at least 6 months. In two other cases with both a continuous and dot-like pattern of deposition, duration of disease was at least 1 and 6 years. We compared the pattern of staining on DIF with the hematoxylin/eosin findings in lesional skin, whether showing subcorneal acantholysis (consistent with pemphigus foliaceus) or suprabasilar acantholysis (consistent with pemphigus vulgaris). In photographs of immunofluorescence results in cases where the entire epidermis was photographed, there was uniform epidermal staining without accentuation of immunoreactants in the superficial epidermis in 4/4 cases of pemphigus foliaceus, and there was slight accentuation of staining in the suprabasilar area in 7/10 cases of pemphigus vulgaris. We also assessed the degree of acantholysis and inflammation in frozen section routinely stained slides, which were available for the majority of cases, prepared from the same tissue submitted for DIF (Table 3). In cases with a punctate pattern, 6/7 (86%) of available slides showed widespread vesiculation of the epidermis secondary to acantholysis, and 1 case (14%) lacked visible acantholysis. Cases with a continuous pattern of intercellular reactants showed epidermal vesiculation in 5/12 (45%), subtle focal acantholysis in 5/12 (45%) and no acantholysis in 2/12 (10%). A mixed pattern of punctate and continuous intercellular reactants was associated with epidermal vesiculation in 4/10 (40%), subtle focal acantholysis in 5/10 cases (50%) and no acantholysis in 1/10 (10%). Discussion A punctate or dot-like pattern is not infrequently seen in DIF studies of pemphigus vulgaris and pemphigus
foliaceus (Figs. 1 and 2). In total, the punctate pattern occurred alone or in conjunction with a typical continuous intercellular pattern in 62% (23/37) of all cases and was the only immunofluorescence pattern in 27% (10/37) of cases (Fig. 3). The punctate pattern was as likely as the continuous pattern of deposition to correspond to histopathological features diagnostic of pemphigus, including either suprabasilar or subcorneal acantholysis. Because both punctate and continuous patterns were seen together in 13 cases, the punctate pattern does not seem to correspond to tissue section thickness or age of lesion. It has previously been suggested that pemphigus foliaceus shows increased deposition of immunoreactants in the superficial epidermis vs. pemphigus vulgaris showing preferential labeling of the lower portion of the epidermis. In our study, staining of the suprabasal area was accentuated in the majority of cases (7/10) of pemphigus vulgaris but localized more superficial staining was not observed in pemphigus foliaceus; a limitation is that we had only four cases of pemphigus foliaceus in which the entire epidermis was well-visualized. The punctate pattern did not differentiate these subtypes of pemphigus. Laboratory studies have shown that serum from patients with pemphigus causes depletion of desmoglein 1 (in particular interdesmosomal desmoglein 1)8 and desmoglein 3 (interdesmosomal and desmosomal) from the cell membrane.9 Perhaps in vivo, the dot-like immunofluorescence pattern corresponds to increased distance between desmogleincontaining desmosomes, with less confluence of the immunofluorescence signal, particularly in cases where interdesmosomal desmoglein 1 is absent.8 This would be supported by (a) the spectrum of patterns of intercellular immunofluorescence from distinct separate punctate dots, to stippled continuous dots, to a smooth confluent chicken-wire intercellular pattern and (b) our cases with both continuous and punctate deposition, in which the dot-like pattern was more often in the lower half of the epidermis, which has less desmoglein 1 compared to the superficial epidermis. Greater distance between desmosomes (leading to a punctate pattern) could also be secondary to acantholysis. In a review of frozen section routinely stained slides accompanying our DIF studies, we found vesiculation secondary to acantholysis in tissue submitted for DIF more often in cases with a punctate pattern (86%) compared to vesiculation in cases with a continuous pattern (42%) or a mixed pattern (40%). However, some cases in each category showed mild or no acantholysis and some cases with a continuous pattern showed substantial acantholysis causing vesiculation, suggesting that the degree of acantholysis in tissue does not fully explain the difference in DIF patterns. Similarly,
295
Ko & McNiff the presence of inflammation was comparable in all groups. It is also possible that laboratory techniques account for the difference in staining patterns. The use of surfactant in our buffer could result in exposure of epitopes not otherwise affected by phosphate buffered saline alone. However, all cases in our series were prepared with identical methods and reactants, and only a subset showed a punctate pattern; thus, the presence of surfactant in buffer is not fully responsible for the variable staining patterns. The punctate pattern of immunoreactants pemphigus should not be confused with a false-positive reaction. Rarely, linear to coarse, intercellular deposition of C3 alone on DIF has been described
in drug reactions or connective tissue diseases.10 In these cases, IgG deposition is not reported.8 This series highlights the common occurrence of a punctate or dot-like pattern of deposition of intercellular immunoreactants in pemphigus. This pattern should not be interpreted as a false positive reaction merely because continuous intercellular staining is absent. Moreover, the punctate pattern of immunofluorescence in pemphigus is underreported in the literature and underemphasized or even overlooked in many textbooks. Recognition of this pattern is critical in establishing the correct diagnosis of pemphigus and allowing for treatment of this potentially serious condition.
References 1. Wu H, Brandling-Bennett HA, Harrist TJ. Chapter 9: Noninfectious vesiculobullous and vesiculopustular diseases. In Elder DE, Elenitsas R, Johnson BL Jr, Murphy GF, Xu X, eds. Lever’s histopathology of the skin, 10th ed. Philadelphia: Lippincott Williams and Wilkins, 2009; 248. 2. Weedon D. Chapter 6: The vesiculobullous reaction pattern. In Weedon D, Weedon’s skin pathology, 3rd ed. China: Elsevier, 2010; 137. 3. Amagai M. Chapter 29: Pemphigus. In Bolognia JL, Jorizzo JL, Schaffer JV, et al., eds. Dermatology, 3rd ed. China: Elsevier, 2012; 470. 4. Krasny SA, Beutner EH, Chorzelski TP. Chapter 9: Specificity and sensitivity of indirect and direct immunofluorescent findings
296
in the diagnosis of pemphigus. In Beutner EH, Chorzelski TP, Kumar VJ, eds. Immunopathology of the skin, 3rd ed. New York: John Wiley & Sons, Inc., 1987; 210. 5. Megahed M. Histopathology of blistering diseases. Berlin: Springer, 2004; 74. 6. Rappersberger K, Roos N, Stanley JR. Immunomorphologic and biochemical identification of the pemphigus foliaceus autoantigen within desmosomes. J Invest Dermatol 1992; 99: 323. 7. Akiyama M, Hashimoto T, Sugiura M, Nishikawa T. Ultrastructural localization of pemphigus vulgaris and pemphigus foliaceus antigens in cultured human squamous carcinoma cells. Br J Dermatol 1991; 125: 233.
8. Lanza A, De Rosa A, Femiano F, et al. Internalization of non-clustered desmoglein 1 without depletion of desmoglein 1 from adhesion complexes in an experimental model of the autoimmune disease pemphigus foliaceus. Int J Immunopathol Pharmacol 2007; 20: 355. 9. Aoyama Y, Nagai M, Kitajima Y. Binding of pemphigus vulgaris IgG to antigens in desmosome core domains excludes immune complexes rather than directly splitting desmosomes. Br J Dermatol 2010; 162: 1049. 10. Krasny SA, Kumar V, Tarfare N, Beutner EH, Chorzelski TP. Intercellular complement C3 binding in normal skin of patients without pemphigus. J Am Acad Dermatol 1986; 14: 52.
J Cutan Pathol 2014: 41: 293–296 doi: 10.1111/cup.12272 John Wiley & Sons. Printed in Singapore
Journal of Cutaneous Pathology
Punctate pemphigus: an underreported direct immunofluorescence pattern Intercellular epidermal deposition of immunoglobulin G (IgG) in a continuous net-like or ‘chicken wire’ pattern is a well-described and diagnostic finding in direct immunofluorescence (DIF) studies of pemphigus. In our experience, punctate or dot-like intercellular deposition of IgG can also be seen in cases of pemphigus but has received little attention in the literature. We describe a series of DIF specimens showing intercellular deposition of IgG in continuous and/or punctate patterns, which occurred with equal frequency in pemphigus vulgaris and pemphigus foliaceus. This series highlights the punctate or dot-like pattern of intercellular IgG deposition in DIF studies of pemphigus, reviews potential mechanisms and calls attention to this potentially under-recognized phenomenon.
Christine J. Ko and Jennifer M. McNiff
Keywords: desmosome, dot-like, immunofluorescence, pemphigus, punctate
Associate Prof. Christine Ko, MD Dermatology and Pathology, Yale University, New Haven, CT, USA Tel: +1 203 785 4094 Fax: 203-785-6869 e-mail: [email protected]
Ko CJ, McNiff JM. Punctate pemphigus: an underreported direct immunofluorescence pattern. J Cutan Pathol 2014; 41: 293–296. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Intercellular continuous net-like deposition of immunoglobulin G (IgG) and C3 in the epidermis is well-recognized and diagnostic of pemphigus.1 – 5 In practice, we have noted that some specimens have an interrupted, punctate intercellular pattern of immunoreactant deposition corresponding to cases of pemphigus with otherwise typical clinical and histopathological findings. This punctate pattern is only briefly mentioned in a few textbooks1 and is largely overlooked in many standard dermatopathology references.2,5 The identification of intercellular dot-like positivity by direct immunofluorescence (DIF) studies presumably reflects localization of desmogleins 1 and 3 (the antigens of pemphigus) to desmosomes.6,7 This punctate pattern may reflect the exact location of the target desmoglein antigens within desmosomes7 and/or correspond to older lesions showing aggregation of desmosomes1 due to
Dermatology and Pathology, Yale University, New Haven, CT, USA
Accepted for publication November 20, 2013
well-developed acantholysis. This report describes the finding of punctate intercellular deposition of IgG in pemphigus in greater detail, and reviews potential implications of this observation. Materials and methods We searched our laboratory database for all DIF cases showing an intercellular pattern of deposition of IgG and/or C3 in cases accessioned from December 15, 2004 to October 3, 2013. Immunofluorescence patterns were assessed by retrospective review of photomicrographs illustrating positive staining where available. In addition, separate companion biopsies, typically representing lesional tissue processed and stained with hematoxylin and eosin, were reviewed for subcorneal and suprabasilar acantholysis, subcorneal and intraepidermal eosinophils and neutrophils, and eosinophilic spongiosis in 24 cases.
293
Ko & McNiff Table 1. Pattern of immunoglobulin G (IgG) deposition on direct immunofluorescence (DIF) for 37 cases of pemphigus Pattern
Number of Final diagnosis cases (number of cases)*
Continuous [net-like (lace-like)]
14
Continuous and punctate
13
Punctate alone
10
Pemphigus vulgaris (3) Pemphigus foliaceus (1) Pemphigus, NOS (10) Pemphigus vulgaris (6) Pemphigus foliaceus (3) Pemphigus, NOS (4) Pemphigus vulgaris (4) Pemphigus foliaceus (2) Pemphigus, NOS (4)
Table 2. Hematoxylin and eosin findings and corresponding diagnoses in 24 cases Hematoxylin and eosin characteristic Suprabasilar acantholysis Subcorneal acantholysis Subcorneal neutrophils/pustules Eosinophilic spongiosis
Final diagnosis*
Number of cases
Pemphigus vulgaris
13
Pemphigus foliaceus Pemphigus foliaceus, favored
6 1
Pemphigus, NOS
4
NOS, not otherwise specified. *After correlation with clinical and hematoxylin/eosin findings.
*After correlation with clinical and hematoxylin/eosin findings in 24 cases.
Fig. 1. Pemphigus. Direct immunofluorescence staining for immunoglobulin G (IgG) shows irregular intercellular punctate dots of variable size.
For the majority of cases, frozen hematoxylin and eosin-stained sections of perilesional tissue submitted for immunofluorescence testing were available for review. DIF testing was performed using a Dako Autostainer Plus (Dako, Carpinteria, CA, USA) with frozen sections of patient skin biopsies cut at 6 μ, labeled with fluorescein-conjugated goat anti-human antibodies in phosphate buffered saline (PBS) with 0.05% Tween 20 surfactant, directed against IgG (dilution 1 : 75), C3 (dilution 1 : 75), IgM (dilution 1 : 50), IgA (dilution 1 : 25) and fibrinogen (dilution 1 : 100) (MP Biomedicals, Solon, OH, USA). Appropriate controls were run in parallel. Results Over approximately 9 years, there were 66 DIF cases consistent with pemphigus, which were characterized by intercellular IgG and/or C3 deposits. The vast majority had deposition of both IgG and C3, with 10 cases having IgG without C3. Thirty-seven of these cases had high-resolution photomicrographs of DIF with IgG available for review and results are shown in Table 1. The punctate pattern was sometimes composed of uniform intercellular dots and sometimes dots of irregular size (Fig. 1). Hematoxylin and
294
Fig. 2. Pemphigus. Direct immunofluorescence staining for immunoglobulin G (IgG) shows a combined pattern, with uniform, punctate intercellular dots in the lower half of the epidermis and a continuous, net-like intercellular pattern of IgG deposition in the upper half of the epidermis.
Fig. 3. Pemphigus. Direct immunofluorescence staining shows a relatively continuous or net-like pattern of immunoglobulin G (IgG) deposition. On close inspection, particularly in the basal layer, there are a few, scattered intercellular dots.
eosin findings from separate lesional biopsies are documented in Table 2. In cases with both dot-like and continuous patterns, the continuous net-like pattern was often most evident in the superficial epidermis, whereas the dot-like pattern was more prevalent in the lower one-half of the epidermis (Fig. 2). In a few of the cases classified as having a continuous pattern, on close inspection, a few dots were sometimes present, especially in the basal layers (Fig. 3).
Punctate pemphigus Table 3. Degree of acantholysis and inflammation in hematoxylin/eosin-stained frozen section slides accompanying direct immunofluorescence (DIF) specimens
Vesiculation from acantholysis Subtle focal acantholysis No acantholysis Dermal inflammation
Punctate pattern
Continuous pattern
Continuous and punctate pattern
6/7 (86%)
5/12 (42%)
4/10 (40%)
0/10 (0%)
5/12 (42%)
5/10 (50%)
1/7 (14%) 7/7 (100%)
2/12 (10%) 2/12 (83%)
1/10 (10%) 9/10 (90%)
The duration of disease was known in only four cases. One case with a continuous pattern of deposition was from a patient whose initial diagnosis of pemphigus vulgaris was 18 years prior. One case with a dot-like pattern of deposition had documented pemphigus vulgaris for at least 6 months. In two other cases with both a continuous and dot-like pattern of deposition, duration of disease was at least 1 and 6 years. We compared the pattern of staining on DIF with the hematoxylin/eosin findings in lesional skin, whether showing subcorneal acantholysis (consistent with pemphigus foliaceus) or suprabasilar acantholysis (consistent with pemphigus vulgaris). In photographs of immunofluorescence results in cases where the entire epidermis was photographed, there was uniform epidermal staining without accentuation of immunoreactants in the superficial epidermis in 4/4 cases of pemphigus foliaceus, and there was slight accentuation of staining in the suprabasilar area in 7/10 cases of pemphigus vulgaris. We also assessed the degree of acantholysis and inflammation in frozen section routinely stained slides, which were available for the majority of cases, prepared from the same tissue submitted for DIF (Table 3). In cases with a punctate pattern, 6/7 (86%) of available slides showed widespread vesiculation of the epidermis secondary to acantholysis, and 1 case (14%) lacked visible acantholysis. Cases with a continuous pattern of intercellular reactants showed epidermal vesiculation in 5/12 (45%), subtle focal acantholysis in 5/12 (45%) and no acantholysis in 2/12 (10%). A mixed pattern of punctate and continuous intercellular reactants was associated with epidermal vesiculation in 4/10 (40%), subtle focal acantholysis in 5/10 cases (50%) and no acantholysis in 1/10 (10%). Discussion A punctate or dot-like pattern is not infrequently seen in DIF studies of pemphigus vulgaris and pemphigus
foliaceus (Figs. 1 and 2). In total, the punctate pattern occurred alone or in conjunction with a typical continuous intercellular pattern in 62% (23/37) of all cases and was the only immunofluorescence pattern in 27% (10/37) of cases (Fig. 3). The punctate pattern was as likely as the continuous pattern of deposition to correspond to histopathological features diagnostic of pemphigus, including either suprabasilar or subcorneal acantholysis. Because both punctate and continuous patterns were seen together in 13 cases, the punctate pattern does not seem to correspond to tissue section thickness or age of lesion. It has previously been suggested that pemphigus foliaceus shows increased deposition of immunoreactants in the superficial epidermis vs. pemphigus vulgaris showing preferential labeling of the lower portion of the epidermis. In our study, staining of the suprabasal area was accentuated in the majority of cases (7/10) of pemphigus vulgaris but localized more superficial staining was not observed in pemphigus foliaceus; a limitation is that we had only four cases of pemphigus foliaceus in which the entire epidermis was well-visualized. The punctate pattern did not differentiate these subtypes of pemphigus. Laboratory studies have shown that serum from patients with pemphigus causes depletion of desmoglein 1 (in particular interdesmosomal desmoglein 1)8 and desmoglein 3 (interdesmosomal and desmosomal) from the cell membrane.9 Perhaps in vivo, the dot-like immunofluorescence pattern corresponds to increased distance between desmogleincontaining desmosomes, with less confluence of the immunofluorescence signal, particularly in cases where interdesmosomal desmoglein 1 is absent.8 This would be supported by (a) the spectrum of patterns of intercellular immunofluorescence from distinct separate punctate dots, to stippled continuous dots, to a smooth confluent chicken-wire intercellular pattern and (b) our cases with both continuous and punctate deposition, in which the dot-like pattern was more often in the lower half of the epidermis, which has less desmoglein 1 compared to the superficial epidermis. Greater distance between desmosomes (leading to a punctate pattern) could also be secondary to acantholysis. In a review of frozen section routinely stained slides accompanying our DIF studies, we found vesiculation secondary to acantholysis in tissue submitted for DIF more often in cases with a punctate pattern (86%) compared to vesiculation in cases with a continuous pattern (42%) or a mixed pattern (40%). However, some cases in each category showed mild or no acantholysis and some cases with a continuous pattern showed substantial acantholysis causing vesiculation, suggesting that the degree of acantholysis in tissue does not fully explain the difference in DIF patterns. Similarly,
295
Ko & McNiff the presence of inflammation was comparable in all groups. It is also possible that laboratory techniques account for the difference in staining patterns. The use of surfactant in our buffer could result in exposure of epitopes not otherwise affected by phosphate buffered saline alone. However, all cases in our series were prepared with identical methods and reactants, and only a subset showed a punctate pattern; thus, the presence of surfactant in buffer is not fully responsible for the variable staining patterns. The punctate pattern of immunoreactants pemphigus should not be confused with a false-positive reaction. Rarely, linear to coarse, intercellular deposition of C3 alone on DIF has been described
in drug reactions or connective tissue diseases.10 In these cases, IgG deposition is not reported.8 This series highlights the common occurrence of a punctate or dot-like pattern of deposition of intercellular immunoreactants in pemphigus. This pattern should not be interpreted as a false positive reaction merely because continuous intercellular staining is absent. Moreover, the punctate pattern of immunofluorescence in pemphigus is underreported in the literature and underemphasized or even overlooked in many textbooks. Recognition of this pattern is critical in establishing the correct diagnosis of pemphigus and allowing for treatment of this potentially serious condition.
References 1. Wu H, Brandling-Bennett HA, Harrist TJ. Chapter 9: Noninfectious vesiculobullous and vesiculopustular diseases. In Elder DE, Elenitsas R, Johnson BL Jr, Murphy GF, Xu X, eds. Lever’s histopathology of the skin, 10th ed. Philadelphia: Lippincott Williams and Wilkins, 2009; 248. 2. Weedon D. Chapter 6: The vesiculobullous reaction pattern. In Weedon D, Weedon’s skin pathology, 3rd ed. China: Elsevier, 2010; 137. 3. Amagai M. Chapter 29: Pemphigus. In Bolognia JL, Jorizzo JL, Schaffer JV, et al., eds. Dermatology, 3rd ed. China: Elsevier, 2012; 470. 4. Krasny SA, Beutner EH, Chorzelski TP. Chapter 9: Specificity and sensitivity of indirect and direct immunofluorescent findings
296
in the diagnosis of pemphigus. In Beutner EH, Chorzelski TP, Kumar VJ, eds. Immunopathology of the skin, 3rd ed. New York: John Wiley & Sons, Inc., 1987; 210. 5. Megahed M. Histopathology of blistering diseases. Berlin: Springer, 2004; 74. 6. Rappersberger K, Roos N, Stanley JR. Immunomorphologic and biochemical identification of the pemphigus foliaceus autoantigen within desmosomes. J Invest Dermatol 1992; 99: 323. 7. Akiyama M, Hashimoto T, Sugiura M, Nishikawa T. Ultrastructural localization of pemphigus vulgaris and pemphigus foliaceus antigens in cultured human squamous carcinoma cells. Br J Dermatol 1991; 125: 233.
8. Lanza A, De Rosa A, Femiano F, et al. Internalization of non-clustered desmoglein 1 without depletion of desmoglein 1 from adhesion complexes in an experimental model of the autoimmune disease pemphigus foliaceus. Int J Immunopathol Pharmacol 2007; 20: 355. 9. Aoyama Y, Nagai M, Kitajima Y. Binding of pemphigus vulgaris IgG to antigens in desmosome core domains excludes immune complexes rather than directly splitting desmosomes. Br J Dermatol 2010; 162: 1049. 10. Krasny SA, Kumar V, Tarfare N, Beutner EH, Chorzelski TP. Intercellular complement C3 binding in normal skin of patients without pemphigus. J Am Acad Dermatol 1986; 14: 52.
