Extremely Rare Primary Gastric Alveolar Rhabdomyosarcoma in an Adult: ¹⁸F-FDG PET/CT Findings

Approximately 85-90% of all rhabdomyosarcoma (RMS) cases occur in children and adolescents. In adults, RMS accounts for only 2-5% of all soft tissue sarcomas. The annual incidence in adults is 0.3-0.5 per 1,000,000 and is classified as a "very rare tumor." More than 95% of RMSs are extragastric. Primary gastric RMS is reported extremely rarely in adults, and the estimated incidence is <0.01/1,000,000/year. This rate is <0.01% of all gastric malignancies and <1% of all adult RMSs. We report the ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography findings in an adult with primary gastric alveolar RMS, highlighting the metabolic characteristics of this extraordinarily rare malignancy.