Cutaneous Metastasis of Malignant Mesothelioma to the Head and Neck

Summary: Malignant mesothelioma is a locally aggressive malignancy of the pleural and/or peritoneal cavity. Distant cutaneous metastasis to the head and neck region is extremely rare. Here, we describe two such cases. Case 1: A 64-year-old man diagnosed previously with extensive thoracic and abdominal mesothelioma, developed a right upper lip lesion, which grew rapidly to 15 mm in size and a wedge resection was performed. Case 2: A 77-year-old woman with a history of pleural mesothelioma developed a firm, mobile subcutaneous nodule on the right lateral forehead (23 mm), clinically thought to represent either an epidermal inclusion cyst or a lipoma. Punch biopsy was performed. In both cases, histopathologic evaluation revealed dermal proliferation of epithelioid cells with moderate cytologic atypia and mitotic activity. Immunohistochemical studies revealed the lesional cells to be positive for WT1, mesothelin, D2-40, CK5/6, while being negative for melanocytic and other keratinocytic markers, supporting a diagnosis of metastatic mesothelioma. Awareness of rare instances of cutaneous metastases from malignant mesothelioma is necessary to avoid possible misdiagnosis and ensure appropriate management.