Leydig Cell Tumour — RACP Adult Medicine MCQ

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HardMedical OncologyLeydig Cell TumourRACP Adult Medicine

A 70-year-old man presents with a painless right-sided testicular mass. Ultrasound confirms a solid intratesticular lesion. AFP and beta-hCG are normal. LDH is mildly elevated. He also has bilateral gynaecomastia. What testicular tumour type is associated with gynaecomastia?

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Correct answer: A — Leydig cell tumour

Leydig cell tumours (sex cord-stromal tumours) produce testosterone and/or oestrogen, commonly causing gynaecomastia (due to peripheral aromatisation of testosterone to oestradiol or direct oestrogen production). They are usually benign (90%) and treated with orchidectomy alone. Choriocarcinoma also causes gynaecomastia but through beta-hCG production (which is elevated – normal in this case). Seminomas are the most common testicular GCT overall but don't typically cause gynaecomastia.

Reference: eTG – 2025 – Oncology; EAU – 2024 – Testicular Cancer Guidelines