Suspected hydatid cyst of liver harbouring an aggressive desmoplastic small round cell tumour.

Among the group of small round cell tumours, there is a distinct and rare tumour known as desmoplastic small round cell tumour (DSRCT). DSRCT presents as multiple, widespread masses in the abdomen and pelvis and may be accompanied by extensive tumour implants throughout the peritoneum as the tumour is known to spread diffusely along serosal surfaces. We discuss a case of DSRCT in a 16-year-old boy who presented with abdominal pain since 2 years, a non-tender mass was palpable on the right upper quadrant of the abdomen, ultrasonographic and CT findings suggested hydatid cyst of liver. Laparotomy revealed multiple small peritoneal deposits along with a single mass in the liver. On histopathology, the lesion was found to be neoplastic and composed of predominantly clusters of small round blue cells, in a desmoplastic stroma; tumour cells were diffusely positive for cytokeratin, vimentin and neuron-specific enolase, thus confirming the diagnosis of DSRCT.