[Undifferentiated small cell carcinoma (oat-cell type) of the colon. Prognostic and therapeutic implications]

This report reviews the clinical and pathologic features of four patients with small-cell anaplastic carcinoma (SCAC) of the colon and describes in detail their histological and immunohistochemical characteristics.

Four patients with a SCAC of the colon diagnosed by conventional light microscopy, immunohistochemistry and ultrastructure were reviewed; clinical presentation, tumor location and spread, surgical procedure, adjuvant therapy and clinical outcome were recorded.

There were two women and two man, with an average age of 55 (range, 40-66) years. Two tumors were located in the sigmoid and two in right colon. Cases 1, 3 and 4 were removed at laparotomy by segmental resection along with lymph nodes. All cases had liver metastases. Pathologic study identified out-cell subtype in all cases and two histopathologic patterns: pure SCAC (cases 2 and 4) and mixed exocrine-SCC differentiation (cases 1 and 3). Three patients were treated with cyclophosphamide, cisplatin and etoposide. Two patients (cases 2 and 4) died of widely metastatic disease; cases 1 and 3 had partial remission lasting 9 and 3 months, respectively.

Due to extremely aggressive behavior of colon SCAC with early metastatic spread, CT scans of the chest-abdomen and radionuclide bone scan should be performed. In the presence of metastatic disease, multiagent chemotherapy with combined etoposide and cisplatin should be instituted.