Abstract

The cystic mesothelioma is a very rare tumor which has a clinically and histologically benign nature. Here in reported is the case of a cystic mesothelioma presented as a palpable mass of the inguinal area in a 28-year-old male. Ultrasound showed a cystic tumor at the inguinal canal, and the other physical and laboratory examinations were within normal limits. Grossly, the tumor consisted of cysts containing clear serous fluid and focally solid areas. Microscopically, the tumor was encapsulated with fibrocollagenous wall, and the tumor cells were cuboidal or polygonal epithelial cells with single or multiple layers and had clear cytoplasm. Some areas showed thyroid follicle-like structures. The content of follicle-like structures showed eosinophilia in the H&E section, but positive in mucin stain. Neither cytologic atypia nor mitoses were present. Immunohistochemical staining revealed positive reaction for keratins of low molecular weight, while negative for the thyroglobulin and CEA. These findings suggested mesothelial in origin. We concluded that this tumor was primary rather than metastatic, because he had no evidence of a tumor in gastrointestinal, genitourinary tracts and scrotum.

• Keywords: Cystic mesothelioma;Inguinal;Keratin;