CASE OF THE WEEK
2019-13 / MAY 13
(CONTRIBUTOR: ANDRES MATOSO)
54 yo male with a testicular mass. By immunohistochemistry, tumor cells are positive for cytokeratin AE1/AE3, desmin (perinuclear dot pattern) and WT1.
Quiz
What is the correct diagnosis?
a. Teratoma with somatic malignancy
b. Desmoplastic small round cell tumor
c. Small cell carcinoma
d. Metastatic urothelial carcinoma
1. b
Desmoplastic small round cell tumor
This paratesticular tumor is composed of nests of small round cells with scant cytoplasm and central necrosis. There are areas with spindled morphology. The stroma shows marked desmoplasia. Desmoplastic small round cell tumor is typically located within the abdominal cavity of young patients but can occur at any age. The paratesticular location is another common site of origin. The tumor is characterized by a polyphenotypic immunohistochemical profile that includes positive staining for cytokeratins, desmin and vimentin. The staining for desmin is perinuclear (dot-like/Golgi-like pattern). The majority of cases also show positivity for the Wilms tumor (WT1) protein (nuclear) when using antibodies to the carboxy terminus. Other common positive markers include NSE and CD57. CD99 is positive in 20% of the cases and, together with positive WT1, can lead to a misdiagnosis of Ewing family tumor. S-100 and myogenin are negative. The tumor harbors a t (11;22) involving WT1 and ESWR1, which can be detected by PCR or FISH. The prognosis is poor.
Clinical, pathologic, and molecular spectrum of tumors associated with t(11;22)(p13;q12): desmoplastic small round-cell tumor and its variants.Gerald WL, Ladanyi M, de Alava E, Cuatrecasas M, Kushner BH, LaQuaglia MP, Rosai J.
J Clin Oncol. 1998; 16(9):3028-3036.
Desmoplastic small round cell tumor: I: a histopathologic study of 39 cases with emphasis on unusual histological patterns. Ordóñez NG.
Am J Surg Pathol. 1998 Nov; 22(11):1303-13.
Andres Matoso
Johns Hopkins Hospital
amatoso1@jhmi.edu
Testis
desmoplastic, small round, paratestis