Primary gastric alveolar soft part sarcoma with novel complex chromosomal rearrangements: a case report of endoscopic resection and precision diagnostics

Abstract

Alveolar soft part sarcoma (ASPS) is a rare malignant neoplasm comprising less than 1% of all soft tissue sarcomas, typically affecting adolescents and young adults with a predilection for extremities. Primary gastrointestinal involvement is exceedingly rare, with only a handful of reported cases in the stomach. This article presents a rare case of primary gastric ASPS in a 45-year-old female patient, characterized by novel complex chromosomal rearrangements beyond the canonical ASPSCR1-TFE3 fusion. The tumor was discovered incidentally during endoscopy for dyspepsia. Precision diagnostics, including cytogenetic analysis and fluorescence in situ hybridization (FISH), revealed the characteristic der(17)t(X;17)(p11;q25) rearrangement together with additional chromosomal abnormalities involving chromosomes 1, 5, and 12, suggesting potential modifiers of tumor behavior. Histopathologically, the lesion exhibited classic alveolar architecture with PAS-positive diastase-resistant crystals and TFE3 immunoreactivity. This case underscores the evolving role of endoscopic techniques in managing early-stage visceral sarcomas and the importance of advanced genomic profiling for personalized therapy. A comprehensive literature review integrates findings from English and Persian sources, highlighting diagnostic challenges, genetic heterogeneity, and therapeutic implications. This report advances understanding of ASPS in atypical sites and advocates for multidisciplinary approaches in rare sarcomas.