Solitary Fibrous Tumour of the Mesentery: An Uncommon Site for a Rare Tumour.

Solitary fibrous tumour (SFT), a unique spindle-cell neoplasm, was first identified in the pleura and was earlier named as haemangiopericytoma. The origin of SFT is not well established; however, it has recently been described as a mesenchymal neoplasm, probably arising from the ubiquitous dendritic interstitial cells. SFTs are predominantly benign tumours with a low risk of malignant transformation and are commonly seen in the intrathoracic region, seldom involving extrapleural locations. Although SFTs are extensively documented in medical literature, those originating in the mesentery are extremely uncommon. Here, we report an extremely rare case of a 31-year-old woman who presented with abdominal pain and was later diagnosed with SFT of the mesentery of the sigmoid colon based on histomorphology and immunohistochemistry studies. This case highlights that, although uncommon, such differential diagnoses need to be considered in cases of abdominopelvic swellings and must be differentiated from their histological mimickers for better patient care.