Sertoli-Leydig Cell Tumour With Heterologous Elements Presenting as Hyperandrogenaemia and Markedly Elevated...

Sertoli-Leydig cell tumours (SLCTs) are rare ovarian sex cord-stromal tumours that classically present with features of virilisation due to androgen excess and are frequently misdiagnosed as polycystic ovarian syndrome (PCOS). We report a case of a 33-year-old woman with a three-year history of progressive hirsutism, weight gain, and secondary amenorrhoea, initially attributed to PCOS. An incidental pelvic ultrasound arranged in the context of an endocrinology review revealed a large complex solid-cystic mass measuring 21.2 × 13.8 × 23.4 cm. Tumour markers demonstrated a markedly elevated alpha-fetoprotein (AFP) of 8,147 KU/L, raising initial suspicion of a yolk sac (germ cell) tumour. CT imaging confirmed a 23 cm predominantly cystic pelvic mass with no evidence of metastatic disease. Following multi-disciplinary team discussion and referral to a specialist germ cell tumour MDT, the patient underwent laparotomy and left salpingo-oophorectomy. Initial histology reported an immature teratoma; however, following expert second-opinion review by Professor McCluggage, the final diagnosis was revised to a moderately to poorly differentiated SLCT with heterologous intestinal-type mucinous elements and a small carcinoid component. Ascitic fluid cytology demonstrated no malignant cells. This case highlights the risk of anchoring bias in attributing hyperandrogenaemia to PCOS, the capacity of SLCT with heterologous mucinous elements to mimic germ cell tumours biochemically and histologically, and the indispensable role of expert pathological review in rare ovarian tumours.