Abstract
Testicular and paratesticular tumors resembling mullerian epithelium of the ovary are extremely uncommon. This study reports a case of paratesticular serous papillary adenocarcinoma (SPA) in an 87-year-old man that was misdiagnosed as malignant mesothelioma (MM) and is 37 years older than previous cases, highlighting that SPA does not occur exclusively in young patients as described. Immunohistochemistry revealed expression of pankeratin, CAM 5.2, CK7, CK903, Ber-EP4, vimentin, S100, and CEA and virtually no expression of CK5/6, CK20, calretinin, thrombomodulin, or glypican 3. Expression of adjacent nonneoplastic tunica vaginalis mesothelium was assessed in this patient and additional specimens. Profiles of paratesticular SPA and MM were summarized and compared with paratesticular mesothelium. Nontumoral stromal and entrapped mesothelial expression were 2 diagnostic pitfalls in this case that have not been previously described. Based on these data, a panel of markers and the use of sections containing nonneoplastic mesothelium to facilitate interpretation is recommended.
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