Epididymal adenomatoid tumors are rare, benign neoplasms of mesothelial origin, typically affecting men aged 30-50. They usually present as well-defined, homogeneous masses in the epididymal tail. This report describes an atypical case in a 60-year-old man with a mass in the epididymal head and unusual ultrasonographic features, complicating diagnosis.

A 60-year-old man sought evaluation for a painless, slow-growing right scrotal mass, noticed years earlier but recently prompting concern due to its persistence. He denied trauma, infection, or systemic symptoms like fever or weight loss. Physical exam revealed a 1.5 cm firm, non-tender mass in the right epididymal head, distinct from the testis. Ultrasonography demonstrated a 1.13 x 1.33 cm solid mass with heterogeneous echotexture—predominantly hyperechoic with a hypoechoic segment—and scant vascularity on Doppler, atypical for benign lesions and raising suspicion of malignancy. Lab tests showed normal AFP and β-HCG, but a mildly elevated LDH (228 IU/L) added diagnostic uncertainty. Right scrotal exploration was then performed, during which a grey, firm mass was identified and excised en bloc via a testis-sparing approach. Histopathology revealed tubules and nests of epithelioid cells with positive cytokeratin AE1/AE3 and calretinin staining, diagnostic of an adenomatoid tumor. Postoperatively, the patient recovered uneventfully, with no recurrence at 7-month follow-up.

Paratesticular tumors account for <5% of intrascrotal solid masses, with adenomatoid tumors (30% of cases) being benign and mesothelial in origin. Differential diagnoses include lipomas, leiomyomas, and malignant lesions. Ultrasonography typically shows a well-defined, homogeneous mass with variable echogenicity, though findings are non-specific. Immunohistochemistry (positive for pancytokeratins, podoplanin, WT-1, and calretinin) distinguishes them from vascular tumors (negative endothelial markers). Tumor markers are usually normal. Testis-sparing surgery is ideal for low-malignancy-risk cases, balancing excision with functional preservation.

This case underscores the diagnostic challenge of atypical adenomatoid tumors—unusual age, location, and ultrasound findings—requiring surgery to rule out malignancy. The testis-sparing approach confirmed its benign nature, highlighting the need to consider adenomatoid tumors in atypical presentations and supporting conservative management.