Unmasking the Mimic: Clinicopathologic Insights from Gastrointestinal Leiomyosarcoma

Abstract

Background

Primary leiomyosarcoma (LMS) of the gastrointestinal tract are exceedingly rare smooth muscle tumors accounting for less than 1% of gastrointestinal tract malignancies. In this study, we analyzed specimens of gastrointestinal tractLMS in our tertiary care center and presented their clinicopathological and follow-up details to add to the existing knowledge.

Methods

In this retrospective study conducted over four and a half years between January 2021 and June 2025, a total of 1768 gastrointestinal mesenchymal tumor specimens were assessed for clinical, radiological, histopathological, immunohistochemical, and follow-up data. Their clinical details, radiological findings, histopathological findings, immunophenotype, and follow-up details were analyzed.

Results

A total of 13 (0.7%) primary LMSs of the gastrointestinal tract were identified. The patients’ age ranged from 32 to 78 years, with a mean age of 51.5 years, and with almost equal gender distribution. Common clinical presentations included abdominal mass (77%), abdominal pain (31%), and weakness (23%). One of the ileal LMS had intestinal obstruction, while the rectal LMS had rectal bleeding. Of the total 453 uterine and extrauterine LMS diagnosed during this time, 3% originated in the gastrointestinal tract. Histologically, tumors were composed of intersecting fascicles of smooth muscle cells, positive for smooth muscle actin, smooth muscle myosin heavy chain (SMMHC/MYH11), and desmin, while negative for KIT (CD117) and DOG1 (ANO1). Distant metastases were not observed.

Conclusions

Gastrointestinal tractLMS are rare tumors mimicking gastrointestinal stromal tumors clinicoradiologically. A definitive diagnosis requires histopathology and immunophenotyping. Surgery is the primary treatment, but recurrence necessitates a long-term follow-up.