Primary Mucinous Ovarian Carcinoma: Insight into a Rare Histology and Impact of Pattern of Infiltration on...

Primary mucinous ovarian carcinomas (pMOCs) are a rare subtype of epithelial ovarian cancer which have a unique biological behaviour. These tumours have been divided into patterns of infiltration, namely expansile and infiltrative types, which in turn have prognostic significance. A hospital-based, retrospective analytical cohort study was conducted at a tertiary cancer center in Northeast India, from September 2019 to September 2023. The objectives were to study the impact of pattern of infiltration on oncological outcomes and to prognosticate them. Histology slides of the diagnosed cases were re-examined according to WHO protocol. Overall incidence of pMOC in our study was 3.3% (32/958 patients). Review of histology slides excluded 8 cases. The expansile pattern was seen in 71.9% (n = 23), and infiltrative pattern in 28.1% (n = 9). The most common presenting stage at diagnosis was IA in both expansile (30.4%, n = 7) and infiltrative (44.4%, n = 9) types. Intraoperative frozen section was used in 7 cases with a concordance rate of 14.2% (n = 1). Recurrence was observed in 11 patients (infiltrative = 55.5%, n = 5; expansile = 26%, n = 6). The median recurrence-free interval (RFI) was 28 months in the expansile group and 21 months in the infiltrative group. All recurrences were intra-peritoneal, most common in the pelvis (45.5%), followed by omento-peritoneal (18.2%). Lymphadenectomy was carried out in 56.2% (n = 18) patients (infiltrative = 88.8%, n = 8; expansile = 43.7%, n = 10); in 1 case of infiltrative type, it was reported as positive. Infiltrative histology was associated with more recurrences and lower median survival. Peritoneal staging adds to the quality of surgery; however, the role of lymphadenectomy needs careful consideration.