# When a Lower Abdominal Lump Turned Out to Be a Stromal Tumor of Unknown Malignant Potential

## TL;DR

A 23-year-old woman with a large abdominal mass was diagnosed with a rare stromal tumor of unknown malignant potential, highlighting the importance of accurate diagnosis and follow-up.

## Contribution

This case highlights the diagnostic challenges and management of extrauterine STUMP in young females.

## Key findings

- MRI and PET imaging suggested a low-grade stromal lesion in a young female.
- Histopathology confirmed a smooth muscle tumor with atypia but no necrosis, consistent with STUMP.
- The patient remained free of recurrence or metastasis at six months post-surgery.

## Abstract

Abdominopelvic masses usually do not occur in young females and should be evaluated carefully to rule out rare smooth muscle tumors. Here, we present the case of a 23-year-old female who complained of pain in the lower abdomen, urinary frequency, constipation, and dysuria for the last two months. The examination showed a solid, immobile lower abdominal mass measuring approximately 20 × 25 cm. MRI revealed a clear-cut abdominopelvic lesion measuring 7.9 × 19.7 × 30.4 cm, and fluorodeoxyglucose-positron emission tomography depicted subtle hypermetabolic activity, indicative of a low-grade stromal lesion. During an exploratory laparotomy, a large mass arising on the right broad ligament was noted, and total excision was performed. Histopathology revealed a smooth muscle tumor with mild-to-moderate atypia, low mitotic activity, and absence of coagulative necrosis, which was consistent with a diagnosis of stromal tumor of unknown malignant potential (STUMP). The course after surgery was uneventful, and at the six-month follow-up, the patient did not show any metastasis or recurrence. This case described the diagnostic difficulties of extrauterine STUMP and the significance of histopathological verification and regular follow-up surveillance.