Gastric Leiomyosarcoma Unmasked by Bleeding From a Percutaneous Endoscopic Gastrostomy Tube

Gastric Leiomyosarcoma in Post-Gastrointestinal Stromal Tumor Era: Revisit

Primary gastric leiomyosarcoma is an exceptionally rare disease. This review covers 41 post-gastrointestinal stromal tumor (GIST) era gastric leiomyosarcoma cases that are supported by immunohistochemistry markers. Other spindle cell lesions are also excluded through histological and immunohistochemistry evaluations. The patients range from 3 to 82 years old, with an average age of 54.6 years. The male-to-female ratio is 1.4:1, from diverse geographic areas. Patients may experience abdominal symptoms, and tumor sizes vary between 1 cm and 22 cm. Morphologically, tumors originate from the muscularis propria or the muscularis mucosae, well-circumscribed with spindle cells arranged in fascicule. Tumoral cells exhibit positivity for smooth muscle markers while being negative for GIST markers and others. The mitotic index ranges from 2 to 500/50 high power field. Ki-67 index varies from 15% to 70%. Management typically involves gastrectomy and other appropriate treatments, with tumor recurrence being uncommon. 56% of patients are alive, with 5 patients dying from this disease. Statistical analyses conducted on post-GIST era cases reveal that a mitotic index of ≥100/50 high power field, tumor recurrence, metastasis, or positive lymph nodes significantly correlate with prognosis.

The first case of gastric leiomyosarcoma developed through malignant transformation of leiomyoma

Malignant transformation of gastric leiomyoma has not been reported, and therefore it is considered to have virtually no malignant potential. We report a case of gastric leiomyosarcoma arising from leiomyoma. The patient is a 72-year-old man with a submucosal mass measuring 20 mm in diameter, which was incidentally identified by an endoscopic surveillance. A biopsy suggested a diagnosis of leiomyosarcoma, and local excision was performed. Pathological examination revealed that the tumor was composed of two distinct components: typical leiomyoma-like area in the periphery and leiomyosarcoma component exhibiting higher cellularity, prominent nuclear atypia, necrosis, and increased mitosis. Immunohistochemically, in the latter, p53 overexpression, increased Ki-67 labeling index, and attenuated expression of smooth muscle markers were noted. This is the first report to demonstrate the presence of leiomyoma-leiomyosarcoma sequence in the stomach that is well recognized in the uterus. Our observation highlights the potential occurrence of malignant transformation of gastrointestinal leiomyoma.