More Than Meets the Scope: A Case of Metastatic Leiomyosarcoma Diagnosed During Colonoscopy

Publication Date

2025

Presentation Length

Poster/Gallery presentation

College

Thomas F. Frist, Jr. College of Medicine

Department

<--Please Select Department-->

Student Level

Graduate

SPARK Category

Scholarship

Metadata/Fulltext

Metadata ONLY

SPARK Session

Independent Presentation

Presentation Type

Poster

Summary

Introduction:

Leiomyosarcoma (LMS) is a rare and aggressive malignancy arising from smooth muscle, most commonly originating in the uterus or retroperitoneum. Colonic involvement is uncommon and typically presents as a solitary, symptomatic mass. Multifocal, polypoid colonic lesions are exceptionally rare and not well described. We present a case of metastatic LMS of unknown primary origin, first identified during routine colonoscopy as three small, benign-appearing polyps. Their visual similarity to tubular adenomas contributed to atypical presentation and highlights the importance of considering rare malignancies in patients with suspected metastatic disease.

Case Description:

A 59-year-old woman presented with intermittent right-sided abdominal pain and uterine prolapse. Contrast-enhanced CT imaging revealed multiple hepatic lesions concerning for metastases, scattered pulmonary nodules, and cholelithiasis with no evidence of cholecystitis. Colonoscopy performed to evaluate for a gastrointestinal primary source revealed three broad-based, sessile polyps (~6 mm each) in the distal transverse colon, splenic flexure, and descending colon. These polyps appeared endoscopically similar to tubular adenomas. All were removed via cold snare polypectomy.

Histologic analysis showed pleomorphic spindle cells with abundant eosinophilic cytoplasm, severe nuclear atypia, and 22 mitoses per 10 high-power fields. Immunohistochemistry was positive for desmin and smooth muscle actin and negative for CD117, CD34, and S100, consistent with high-grade LMS. EBER in situ hybridization was negative. No definitive primary tumor was identified. The polyps represented metastatic LMS with concurrent liver and lung involvement. The patient declined systemic therapy and transitioned to palliative care.

Discussion:

This case illustrates a rare presentation of metastatic LMS involving the colon as multiple small polyps that closely resembled benign tubular adenomas. Although metastatic disease was suspected based on imaging, the endoscopic visualization was not typical of this malignancy. Multifocal polypoid colonic involvement is exceedingly rare in LMS and is not well characterized in the literature. This case emphasizes the importance of considering uncommon metastatic patterns in patients with suspected disseminated disease. Recognition of such presentations can help guide appropriate diagnostic workup, inform clinical decision-making, and support timely discussions regarding prognosis and treatment goals

This document is currently not available here.

Share

COinS