Thigh mass in a patient with malignant pleural mesothelioma: Metastasis at an unusual site

Soft tissue tumors are a highly heterogeneous group of lesions with varied clinical presentation. The majority is primary tumors and metastatic tumors are very rare. Malignant pleural mesothelioma presenting as a soft tissue mass at a distant site is even rarer and can cause diagnostic challenges both clinically and pathologically. We report a case of malignant pleural mesothelioma presenting as a soft tissue mass in the left thigh. A 59-year-old man, non-smoker, working in a cement factory since 30 years presented with complains of difficulty in walking since 1½ months. Review of his previous medical records revealed malignant pleural mesothelioma, which was diagnosed 9 months before. He had denied chemotherapy and was on Ayurvedic medication. The lesion involved the adjacent intercostal muscles. Few enlarged lymph nodes were noted in mediastinal and cervical regions. Biopsy of left supraclavicular and right cervical lymph nodes showed metastases. Metastasis from malignant pleural mesothelioma to the thigh was confirmed by immunohistochemistry. The tumor was positive for CK5/6, CK7, Calretinin and vimentin and immunonegative for CEA, Napsin A and TTF 1.