Abstract

Malignant mesothelioma arises from serosal membranes of body cavities, and these malignancies are aggressive with low survival rates despite lower rates of metastasis than other lung cancers. Metastasis to the skin is exceedingly rare, which can present a diagnostic challenge.

We performed a retrospective review of patients with biopsy-proven skin metastasis of mesothelioma (years: 2003-2023). Eight patients were identified and met inclusion criteria. The patients were evenly split by sex, with an average age of 65 years at diagnosis. All but one case represented local spread to the chest wall diagnosed at the time of primary tumor excision; one case demonstrated distant metastasis to the skin. In this latter case, a 70-year-old male presented with multiple small firm nodules on the scalp with an onset of approximately 1 year after diagnosis of his pleural epithelioid mesothelioma and initiation of nivolumab and ipilimumab. 

Histopathological examination of suspected distant cutaneous metastasis of mesothelioma is difficult despite categorization into subtypes: epithelioid, sarcomatous, and biphasic. In this case series, there were seven epithelioid cases and one biphasic case. While immunohistochemistry may aid the diagnosis, there is a notable lack of both sensitive and specific staining.  Dermal & subcutaneous involvement of mesothelioma is more likely due to the local tumor spread which is more easily diagnosed at the time of primary tumor excision. 

Distant metastasis of mesothelioma to the skin is an exceedingly rare event, for which the clinical presentation can be rather nonspecific, and the history of mesothelioma is of paramount importance.