An unusual presentation of aggressive fibromatosis (retroperitoneal desmoid tumour) in pelvic cavity presented as obstructed labour.

Retroperitoneal desmoid tumours are uncommon tumours usually occurring in young females in their reproductive age group and commonly have a benign course but sometimes they can become malignant. These tumours belong to family of myofibroblastic fibromatosis. These tumours are composed of fibroblastic cells with bands of collagen and ill defined cytoplasm and rarely show mitosis. Recurrence is common especially after incomplete excision. Retroperitoneal desmoid is an uncommon tumour among desmoid group which led to an obstructed labour. Here a 28-year-old female diagnosed to have a pelvic desmoid, was missed during the antenatal check-up, presented as an obstructed labour which necessitated a caesarean section. The patient underwent a definitive surgery three months later for excision of tumour. The tumour was excised through a combined abdominal and gluteal incision. Histopathological report revealed an aggressive fibromatosis (retroperitoneal desmoid).