Leiomyomas are small benign smooth muscle lesions arising from the muscularis mucosae of the colorectum. Bland spindle-shaped smooth muscle cells in whorling fascicles, without significant pleomorphism or mitotic activity, merging into the muscularis mucosae.
Spindle-cell tumors are quite rare in the GI tract, but they do occur in two locations, in the esophagus and arising from the muscularis mucosa of the colorectum. In the rest of the GI tract, GI stromal tumors predominate.
Of interest in the esophagus:
Esophageal leiomymomas has a mean age of 30-35 years at the time of diagnosis; colonic leiomyomas have a median age of 62 with a male predilection (M:F is 2.4:1).3 These lesions are usually asymptomatic, but esophageal leiomyomas may present with dysphagia and epigastric pain if the polypoid mass protrudes into the lumen. Small leiomyomas of the colorectum (arising from the muscularis mucosa) may look like small polyps to the endoscopist. 1,2
Lesions are usually small sessile polyps, and removed by endoscopic snare polypectomy.
Benign. However, leiomyosarcomas of the GI tract carry a mortality rate of 75%.1
1 Iacobuzio-Donahue CA, Montgomery EA. Gastrointestinal and Liver Pathology: Foundations in Diagnostic Pathology. Philadelphia, PA: Elsevier; 2005: 210-2.
2 Fenoglio-Preiser CM, et al. Gastrointestinal Pathology: An Atlas and Text. 3rd Ed. Philadelphia, PA: Lippincoott Williams & Wilkins; 2008: 1219-1221.
3 Montgomery, EA. Biopsy Interpretation of the Gastrointestinal Tract Mucosa. Philadelphia, PA: Lippincott Williams & Wilkins: 2006; 305-6.
Miettinen M, Sarlomo-Rikala M, Sobin LH. Mesenchymal tumors of muscularis mucosae of colon and rectum are benign leiomyomas that should be separated from gastrointestinal stromal tumors--a clinicopathologic and immunohistochemical study of eighty-eight cases.Mod Pathol. 2001 Oct;14(10):950-6.