Abstract

Small cell carcinoma of the lung is characterized by cells with finely stippled chromatin and scanty cytoplasm as well as a particularly aggressive clinical course and favorable response to the chemotherapy. Recently percutaneous fine needle aspiration(FNA) biopsy has become both widely established and highly respected for the diagnosis of lung cancer. However metastatic small cell carcinoma of lymph node should be cytologically differentiated from the small round cell tumor of particular sites, especially malignant lymphoma, because small cell carcinoma of classic oat cell type may simulate small cell non-Hodgkin's lymphoma. We report five cases of metastatic small cell carcinoma of intermediate cell type diagnosed by FNA of the enlarged lymph nodes of the neck and axilla. The cytologic smears contained diffuse small neoplastic cells larger than lymphocytes with dense, pyknotic nuclei and extremely scanty cytoplasm. Apparently viable large tumor cells have vesicular nuclei with granular, sometimes very coarse chromatin. The characteristic cytologic features of small cell carcinoma as compared to malignant lymphoma were as follows.: 1) small cells with dense pyknotic nuclei are evenly distributed in the background of apparently viable larger tumor cells, admixed with mature lymphocytes and phagocytic macrophages. 2) small loose aggregates of cells with nuclear molding are indicative of small cell carcinoma rather than non-Hodgkin's lymphoma. 3) the cytoplasmic and nuclear fragments of tumor necrosis are more dominant in the smears of small cell carcinoma. 4) nuclear membrane and nucleoli are generally indistinct in small cell carcinoma due to condensation of chromatin.

• Keywords: Fine needle aspiration cytology;Small cell carcinoma;Non-Hodgkin's lymphoma;