Multiple skeletal muscle metastases from malignant pleural mesothelioma

A 54-year-old male patient (occupational asbestos exposure over 27 years) died 2 years and 4 months after the diagnosis of malignant pleural mesothelioma of the right side, despite twice undergoing pleurectomy and radiotherapy. The autopsy revealed a locally advanced pleural mesothelioma of both sides involving the pericardium, heart, right diaphragm, liver and peritoneum. Disseminated metastases in numerous lymph nodes and a hematogenous metastatic spread into both lungs, the thyroid gland, peritoneum and skeletal musculature were found. The left temporal muscle and proximal limb skeletal muscles of the right upper arm and both thighs exhibited multiple metastases measuring up to 7 cm in diameter. Microscopically, a biphasic type of mesothelioma was detected. To our knowledge this is the first extensive case report on muscle metastases in malignant mesothelioma. Reviewing the literature, it is thought that in the presented case the long survival time of the patient and his protracted preterminal immobility could have contributed to the unusual formation of multiple skeletal muscle metastases.