Basaloid large cell lung carcinoma presenting as cutaneous metastasis at the colostomy site after abdominoperineal resection for rectal carcinoma.

The occurrence of a tumor at the colostomy site after abdominoperineal resection for rectal carcinoma is rare and it may be related to a previously resected carcinoma or another primary tumor. We report a 61-year-old man who developed an ulcerated skin nodule at her colostomy site 6 years after resection of a rectal adenocarcinoma. Histopathologically, the skin nodule was composed of atypical large and pleomorphic cells with high mitotic rate and they were arranged in nests and within lymphatic channels in the dermis. The neoplastic cells were immunoreactive for cytokeratin (CK) AE1/3, CK7, CK34ßE12, epithelial membrane antigen and vimentin while detection of human papillomavirus and Epstein-Barr virus DNA was negative. A diagnosis of basaloid large cell carcinoma of pulmonary origin was suggested and it was confirmed by computed tomography-guided fine needle aspiration of a right subpleural mass. A metastatic tumor at the colostomy site is an exceptional finding and may be the first manifestation of lung cancer, especially if it consist of pleomorphic large cells with high mitotic rate and basaloid immunophenotype.