Metastasis of Sarcomatoid Malignant Mesothelioma With p16/CDKN2A Deletion Presented as a Subcutaneous Mass in the Back: a Case Report and Review of Literature

Abstract

Background: Sarcomatoid malignant mesothelioma (MM) is a rare and aggressive disease, and its diagnosis is challenging.Case presentation: A 60-year-old man was found a recurrent mass in his right back after the initial resection. A chest CT found right pleural thickening, nodular pleural thickening, pleural effusion, mediastinal and right infraclavicular lymph nodes enlargement, which indicated a right pleura MM. Immunohistochemical (IHC) stains of the resected mass showed sarcomatous atypical spindle cells, which were positive for CK 1/3, CK 5/6, WT1, podoplanin and vimentin, and negative for Napsin A, TTF-1 and CDX2, and fluorescent in situ hybridization (FISH) detected homozygous p16/CDKN2A deletion. The association of the chest CT features and the mass assessment confirmed metastatic MM in the subcutaneous layer of the back. Moreover, PET-CT showed multiple metastases in his brain. He developed massive right pleural effusion and chest tightness soon, and the mass kept growing despite of the local and systemic treatments, and he died from pulmonary failure in 3 months.Conclusion: We described an extremely rare subcutaneous metastasis in the back from sarcomatoid MM. And we made the diagnosis by both histological and molecular analysis of the metastatic lesion. MM patients most likely have subcutaneous metastasis on head, they usually develop pleural effusion, chest pain or dyspnea, and their prognosis is very poor because of late diagnosis and insensitivity to current therapies.