Small Cell Carcinoma of the Kidney: A Case Report and Review of the Literature.

Small cell carcinoma (SCC) accounts for 10% to 20% of all primary malignancies of the tracheobronchial tree. It is defined as a high-grade epithelial neoplasm with neuroendocrine differentiation at both immunohistochemical and ultrastructural levels. The tumor cells in SCCs are less than 3 times the size of lymphocytes, their nucleoli are inconspicuous, and they have scant cytoplasm. Mitotic activity is often very high.[1]

Small cell carcinoma is considered a distinct clinico-pathologic entity owing to its many characteristic clinical manifestations, unique pathologic features, and sensitivity to chemotherapy. Although special techniques such as immunohistochemistry or electron microscopy can be very useful in the evaluation of SCC, the final diagnosis should rest on the routine morphologic features, since the World Health Organization and the International Association for the Study of Lung Cancer define SCC purely by light microscopic criteria.[2]

Small cell carcinoma is now being increasingly reported at extrapulmonary sites, such as the aerodigestive and genitourinary tracts. In all these unusual locations, diagnosis should rest on histopathologic, immunohistochemical, and ultrastructural similarities with respect to the tumor's lung counterpart.[3] Genitourinary SCC is located most often in the prostate and urinary bladder, although there have been isolated reported cases involving the ureter and kidney.[4] We describe the clinical, radiological, morphologic, immunohistochemical, and cytometric DNA (ploidy and S-phase fraction) features of a primary SCC of the kidney. To our knowledge, this case represents the 9th case reported in the literature to date and the first case studied by cytometric analysis.

REPORT OF A CASE

A 76-year-old woman complained of a constitutional syndrome of several months' duration, complicated with gross hematuria during…