DOI: https://doi.org/10.36347/sjmcr.2026.v14i10.002

Pages: 2119-2126

Background. Adult-type granulosa cell tumours (AGCTs) are rare sex cord–stromal neoplasms accounting for fewer than 5% of ovarian cancers. Their hallmark is autonomous oestradiol secretion, and they recur late. Where molecular testing is unavailable, the diagnosis rests on morphology and immunohistochemistry. Case Presentation. A 50-year-old woman was referred for a pelvic mass, abnormal uterine bleeding and a palpable right breast nodule. Abdomino-pelvic MRI showed a multiloculated left ovarian lesion with haemorrhagic content, T2 shading, restricted diffusion and non-enhancing contents, scored O-RADS MRI 4 but reported as suggesting an endometrioma; the endometrium measured 17 mm and was reported as probable hyperplasia, with diffuse adenomyosis. CA-125 was normal. Laparoscopic left salpingo-oophorectomy removed a mass with a 9 × 8 cm solid component; the specimen reached the laboratory in seven fragments, upstaging the tumour to FIGO IC1. Histology showed a microfollicular and trabecular proliferation of monomorphic grooved cells without necrosis, with intraluminal tumour clusters in the tube. Immunohistochemistry was positive for inhibin, calretinin, oestrogen and progesterone receptors and negative for PAX8, CK7, CK20, WT1, chromogranin A, synaptophysin and GATA-3. Completion hysterectomy with omentectomy showed no residual tumour and no endometrial hyperplasia. Four cycles of etoposide–cisplatin were delivered without modification, and imaging confirmed complete morphological remission at eight months. Conclusion. A haemorrhagic AGCT can reproduce the MRI signature of an endometrioma; where the narrative report and the O-RADS score diverge, the score must govern management, including the surgical route. Intraoperative fragmentation upstages the disease and is avoidable. Endometrial thickening requires histological confirmation before it is called hyperplasia.