ABSTRACT
Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare type of kidney tumor that has only been recently described. Furthermore, a case of MTSCC associated with a simultaneous lung cancer in the same patient has never been reported in the literature. In this paper, we describe a kidney tumor that was detected during staging work-up in a 72-year-old lung cancer patient. The kidney tumor was removed and shown to exhibit histological and immunophenotypic features of MTSCC, completely distinct from the pulmonary adenocarcinoma. In addition, this case was unique because it was characterized by neuroendocrine differentiation as well as p53 and Ki-67 overexpression in tumor cells. Therefore, we report a case of MTSCC diagnosed in a patient with pulmonary adenocarcinoma and describe the detailed histologic and immunohistochemical features of MTSCC.