Reactive mesothelial hyperplasia in an orchiectomy specimen. The patient had intractable pain caused by chronic epididymo-orchitis. The submesothelial stroma shows clusters of well-formed glandular structures lined by mesothelial cells. When taken out of context, they may be mistaken for invasive carcinoma. The complete absence of nuclear anaplasia, necrosis, or a grossly visible tumor mass favors a reactive process.