High-Grade Round Cell Neoplasm Presenting as an Anterior Mediastinal Mass With Features of Desmoplastic Round Cell Tumour.

Desmoplastic small round cell tumours (DSRCT) are highly aggressive neoplasms typically affecting adolescent and young adult males. We present a rare case of high-grade round cell tumour with features of DSRCT in a young female who initially presented with anaphylactic reactions to blueberries, which, on further evaluation, revealed an anterior mediastinal mass. Contrast-enhanced CT (CECT) of the thorax demonstrated a large, round cell tumour encasing multiple mediastinal structures, later confirmed by histopathology. The patient was offered combined chemotherapy and radiotherapy; however, she opted to leave against medical advice. This case highlights an unusual presentation of DSRCT and underscores the importance of early recognition and multidisciplinary management.