Cytologic Characteristics of Congenital Mesoblastic Nephroma in Fine-Needle Aspiration Cytology: A Case Report Ricardo Drut,
M.D.
The cytologic features of congenital mesoblastic nephroma (CMN) as recognized in smears of fine-needle aspirated cytology (FiQAC) are reported. These included spindle- and tadpole-shaped cell,s with round to oval nuclei havingsmall nucleoli and a smooth contour. The cytoplasm of these cells was dense and homogeneously stained. The background was composed of mucoid fibrillar material. The findings appear to be different from other types of renal tumors in infancy and speci$c enough for this tumor to allow diagnosis by FNAC. Diagn Cytopathol 1992;8:374-376. @ 1'392 Wiley-Liss, Inc.
Key Words: FNAC; Renal tumors; Infant tumors
Bolande et al. first described CMN as a tumor of early infancy. It is the most common encountered renal neoplasm in the first months of life and not unfrequently is recognized at birth or during the first month. 1-3 Although several papers dealing with the cytologic characteristics of different renal tumors in infancy have recently appeared, 49 this is the first report dealing with the cytologic features of CMN.
Case Report A 1-yr-old girl was admitted to hospital due to a renal tumor. Ultrasound disclosed a solid mass in the left kidney. Percutaneous FNAC was done using a 22-gauge needle and a disposable syringe. Smears were fixed in ethanol and hematoxylin-eosin stained. Although the smears contained many cells interpreted as coming from a tumor, the exact histologic counterpart could not be recognized. The girl received a left nephrectomy. ~
Received May 15, 1991. Accepted October 8, 1991. From the Servicio de Patologia, Hospital de Niiios, La Plata, Argentina. Address reprint requests to Ricardo Drut, M.D., Servicio de Patologia, Hospital de Niiios, 1900 La Plata, Republica Argentina.
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Diagnostic Cytopathology, Vol8, No 4
Cytologic Findings The smears contained small groups and isolated cells against a proteinaceous fibrillary and dotted background. The cells were spindle shaped, and many exhibited a tadpole shape with the nucleous at one end. The nuclei were round to slightly oval and had fine chromatine granules, a small nucleoli, and smooth borders. The cytoplasm was elongated, dense, stained homogeneously, and extended to one or both sides of the nucleous (Fig. 1). A few inflammatory cells were also present.
Pathology Findings The resected kidney contained a 10 X 8 x 5 cm solid tumor, which on sectioning was soft, pinkish in color, and had some myxoid areas, hemorrhagic foci, and small cystic cavities with mucoid fluid. Histologically it was composed of a proliferation of spindle-shaped cells in a fibromatosis-like pattern, with variable cellular density, myxoid areas, and infiltrating borders (Fig. 2). This example did not have areas with the so-called cellular pattern of CMN.
Discussion Although this case is somewhat beyond the mean age for CMN,3 it is clear from the size of the tumor that this lesion had been there for some months before diagnosis. The cytologic characteristics of CMN appear to be peculiar enough as to allow differential diagnosis from other renal tumors of infancy. The smears showed a monomorphous population of bland, spindle-, or tadpole-shaped cells against a fibrillary background. These features seem to be quite different from those found in nephroblastoma, rhabdoid tumor of the kidney, and clear-cell sarcoma of the kidney. 49 0 1992 WILEY-LISS,
INC.
CONGENITAL MESOBLASTIC NEPHROMA IN FNAC
Fig. 1. Spindle- and tadpole-shaped cells with round to oval nuclei with small nucleoli against a fine fibrillary and dotted background, as recognized in the FNAC smears of CMN. The cells in the insets are from other areas of the smears (H&E ~ 4 0 0 )
Classic Wilms’ tumor usually presents smears containing plenty of blastemal cells, which are small round cells with slightly oval nuclei and fine, evenly dispersed chromatin. Most of the cases also include cells of the stromal component, represented by spindle-shaped cells with elongated nuclei in narrow bundles or mixed with blastemal cells in small groups. Epithelial differentiation is also recognized in some cases presenting as tubules or solid strands and cords. A rosetting arrangement of the cells may cause some confusion in the differential diagnosis with neuroblastoma. 4,5 FNAC of rhabdoid tumor is characterized by the presence of the so-called rhabdoid cells, intermediate-sized cells with vesicular nuclei, and prominent nucleoli, exhibiting a paranuclear, eosinophilic, dense inclusion. 6,8 Clear-cell sarcoma of the kidney aspirates produce smears with a monomorphous population of cells having slightly oval bland nuclei with a smooth contour, exhibiting a small nucleolus and frequently a bar of chromatin resulting from grooving or folding of the nuclear membrane and a nondescriptive cytoplasm. 7,9 The presence of a background of mucoid intercellular material is another
feature to be found in these cases. One case, having a histologic epithelioid trabecular pattern, showed smears with vacuolated cells. Although in many countries most children with a renal mass undergo nephrectomy regardless of the nature of the lesion, there are centers that prefer to use preoperative chemotherapy protocols, lo so accurate cytologic recognition appears to be particularly useful. Proper cytologic diagnosis of CMN could avoid unnecessary and potentially dangerous treatments.
References 1. Bolande RP, Bough AJM, Izant RJ. Congenital mesoblastic nephroma of infancy. A report of eight cases and the relationship to Wilms’ tumor. Pediatrics 1967:40:272-8. 2. Bolande RP. Congenital mesoblastic nephroma of infancy, Perspect Pediatr Pathol 1973;1:227-50. 3. Beckwith JB. Renal neoplasms of childhood. In: Diagnostic surgical pathology. Sternberg, SS, ed. New York: Raven Press, 1989: Chap. 39. 4. Quijano G, Drut R. Cytologic characteristics of Wilms’ tumor in fine needle aspirates. A study of ten cases. Acta Cytol 1989;33:263-6. 5 . Akhtar M, Ali MA, Sackey K, Sabbah R, Burgess A. Aspiration cytology of Wilms’ tumor. Diagn Cytopathol 1989;5:269-74.
Diagnostic Cytopathology, Vol 8, No 4
375
DRUT
Fig. 2. (A) Low-power view of the border of the tumor where the fibromatous proliferation is infiltrating the kidney (H&E X40). (B) Histologic section of CMN in an area composed of loose myxoid-like tissue (H&E x 100).
6. Drut R. Malignant rhabdoid tumor of the kidney diagnosed by fine-needle aspiration cytology. Diagn Cytopathol 1990;6:1246. 7. Akhtar M, Ali MA, Sackey K, Sabbah R, Bakry M. Fine needle aspiration biopsy of clear cell sarcoma of the kidney. Light and electron microscopic correlations. Diagn Cytopathol 1989;5:181-5. 8. Akhtar M, Ali MA, Sackey K, Bakry M, Burgess A. Fine-needle aspiration biopsy diagnosis of malignant rhabdoid tumor of the kidney. Diagn Cytopathol 1991;7:3640.
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Diagnostic Cytopathology. Vol 8,No 4
9. Drut R. Cytologic characteristics of clear cell sarcoma of the kidney in fine needle aspirates. Diagn Cytopathol, in press. 10. Lemerle J, Voute PA, Tournade MF, et al. Effectiveness of preoperative chemotherapy in Wilms’ tumor: Results of an International Society of Paediatric Oncology (SIOP) clinical trial. J Clin Oncol 1983;1:604-9.
M.D.
The cytologic features of congenital mesoblastic nephroma (CMN) as recognized in smears of fine-needle aspirated cytology (FiQAC) are reported. These included spindle- and tadpole-shaped cell,s with round to oval nuclei havingsmall nucleoli and a smooth contour. The cytoplasm of these cells was dense and homogeneously stained. The background was composed of mucoid fibrillar material. The findings appear to be different from other types of renal tumors in infancy and speci$c enough for this tumor to allow diagnosis by FNAC. Diagn Cytopathol 1992;8:374-376. @ 1'392 Wiley-Liss, Inc.
Key Words: FNAC; Renal tumors; Infant tumors
Bolande et al. first described CMN as a tumor of early infancy. It is the most common encountered renal neoplasm in the first months of life and not unfrequently is recognized at birth or during the first month. 1-3 Although several papers dealing with the cytologic characteristics of different renal tumors in infancy have recently appeared, 49 this is the first report dealing with the cytologic features of CMN.
Case Report A 1-yr-old girl was admitted to hospital due to a renal tumor. Ultrasound disclosed a solid mass in the left kidney. Percutaneous FNAC was done using a 22-gauge needle and a disposable syringe. Smears were fixed in ethanol and hematoxylin-eosin stained. Although the smears contained many cells interpreted as coming from a tumor, the exact histologic counterpart could not be recognized. The girl received a left nephrectomy. ~
Received May 15, 1991. Accepted October 8, 1991. From the Servicio de Patologia, Hospital de Niiios, La Plata, Argentina. Address reprint requests to Ricardo Drut, M.D., Servicio de Patologia, Hospital de Niiios, 1900 La Plata, Republica Argentina.
374
Diagnostic Cytopathology, Vol8, No 4
Cytologic Findings The smears contained small groups and isolated cells against a proteinaceous fibrillary and dotted background. The cells were spindle shaped, and many exhibited a tadpole shape with the nucleous at one end. The nuclei were round to slightly oval and had fine chromatine granules, a small nucleoli, and smooth borders. The cytoplasm was elongated, dense, stained homogeneously, and extended to one or both sides of the nucleous (Fig. 1). A few inflammatory cells were also present.
Pathology Findings The resected kidney contained a 10 X 8 x 5 cm solid tumor, which on sectioning was soft, pinkish in color, and had some myxoid areas, hemorrhagic foci, and small cystic cavities with mucoid fluid. Histologically it was composed of a proliferation of spindle-shaped cells in a fibromatosis-like pattern, with variable cellular density, myxoid areas, and infiltrating borders (Fig. 2). This example did not have areas with the so-called cellular pattern of CMN.
Discussion Although this case is somewhat beyond the mean age for CMN,3 it is clear from the size of the tumor that this lesion had been there for some months before diagnosis. The cytologic characteristics of CMN appear to be peculiar enough as to allow differential diagnosis from other renal tumors of infancy. The smears showed a monomorphous population of bland, spindle-, or tadpole-shaped cells against a fibrillary background. These features seem to be quite different from those found in nephroblastoma, rhabdoid tumor of the kidney, and clear-cell sarcoma of the kidney. 49 0 1992 WILEY-LISS,
INC.
CONGENITAL MESOBLASTIC NEPHROMA IN FNAC
Fig. 1. Spindle- and tadpole-shaped cells with round to oval nuclei with small nucleoli against a fine fibrillary and dotted background, as recognized in the FNAC smears of CMN. The cells in the insets are from other areas of the smears (H&E ~ 4 0 0 )
Classic Wilms’ tumor usually presents smears containing plenty of blastemal cells, which are small round cells with slightly oval nuclei and fine, evenly dispersed chromatin. Most of the cases also include cells of the stromal component, represented by spindle-shaped cells with elongated nuclei in narrow bundles or mixed with blastemal cells in small groups. Epithelial differentiation is also recognized in some cases presenting as tubules or solid strands and cords. A rosetting arrangement of the cells may cause some confusion in the differential diagnosis with neuroblastoma. 4,5 FNAC of rhabdoid tumor is characterized by the presence of the so-called rhabdoid cells, intermediate-sized cells with vesicular nuclei, and prominent nucleoli, exhibiting a paranuclear, eosinophilic, dense inclusion. 6,8 Clear-cell sarcoma of the kidney aspirates produce smears with a monomorphous population of cells having slightly oval bland nuclei with a smooth contour, exhibiting a small nucleolus and frequently a bar of chromatin resulting from grooving or folding of the nuclear membrane and a nondescriptive cytoplasm. 7,9 The presence of a background of mucoid intercellular material is another
feature to be found in these cases. One case, having a histologic epithelioid trabecular pattern, showed smears with vacuolated cells. Although in many countries most children with a renal mass undergo nephrectomy regardless of the nature of the lesion, there are centers that prefer to use preoperative chemotherapy protocols, lo so accurate cytologic recognition appears to be particularly useful. Proper cytologic diagnosis of CMN could avoid unnecessary and potentially dangerous treatments.
References 1. Bolande RP, Bough AJM, Izant RJ. Congenital mesoblastic nephroma of infancy. A report of eight cases and the relationship to Wilms’ tumor. Pediatrics 1967:40:272-8. 2. Bolande RP. Congenital mesoblastic nephroma of infancy, Perspect Pediatr Pathol 1973;1:227-50. 3. Beckwith JB. Renal neoplasms of childhood. In: Diagnostic surgical pathology. Sternberg, SS, ed. New York: Raven Press, 1989: Chap. 39. 4. Quijano G, Drut R. Cytologic characteristics of Wilms’ tumor in fine needle aspirates. A study of ten cases. Acta Cytol 1989;33:263-6. 5 . Akhtar M, Ali MA, Sackey K, Sabbah R, Burgess A. Aspiration cytology of Wilms’ tumor. Diagn Cytopathol 1989;5:269-74.
Diagnostic Cytopathology, Vol 8, No 4
375
DRUT
Fig. 2. (A) Low-power view of the border of the tumor where the fibromatous proliferation is infiltrating the kidney (H&E X40). (B) Histologic section of CMN in an area composed of loose myxoid-like tissue (H&E x 100).
6. Drut R. Malignant rhabdoid tumor of the kidney diagnosed by fine-needle aspiration cytology. Diagn Cytopathol 1990;6:1246. 7. Akhtar M, Ali MA, Sackey K, Sabbah R, Bakry M. Fine needle aspiration biopsy of clear cell sarcoma of the kidney. Light and electron microscopic correlations. Diagn Cytopathol 1989;5:181-5. 8. Akhtar M, Ali MA, Sackey K, Bakry M, Burgess A. Fine-needle aspiration biopsy diagnosis of malignant rhabdoid tumor of the kidney. Diagn Cytopathol 1991;7:3640.
376
Diagnostic Cytopathology. Vol 8,No 4
9. Drut R. Cytologic characteristics of clear cell sarcoma of the kidney in fine needle aspirates. Diagn Cytopathol, in press. 10. Lemerle J, Voute PA, Tournade MF, et al. Effectiveness of preoperative chemotherapy in Wilms’ tumor: Results of an International Society of Paediatric Oncology (SIOP) clinical trial. J Clin Oncol 1983;1:604-9.
