Abstract
BACKGROUND: Alveolar Soft Part Sarcoma (ASPS) is a rare, highly vascular soft tissue sarcoma characterized by the specific ASPSCR1-TFE3 fusion, typically affecting adolescents and young adults. Despite its often-indolent growth, it has a high propensity for late hematogenous metastasis. Management for localized disease is centered on wide surgical excision. CASE PRESENTATION: We report a case of ASPS in a 44-year-old female from the Ankole tribe, presenting with a slow-growing 8 cm mass in her right upper arm over two years. This age of presentation is outside the typical peak incidence. The diagnosis was established solely on classic histopathological features-a pseudoalveolar pattern, large polygonal cells with abundant eosinophilic cytoplasm, and PAS-positive, diastase-resistant intracytoplasmic granules-due to resource limitations precluding molecular confirmation (TFE3 IHC/FISH). She underwent wide local excision with negative margins and remains free of recurrence at 12 months post-surgery. CONCLUSION: This case highlights the occurrence of ASPS in an older-than-typical patient and underscores the enduring reliability of classic histopathology for definitive diagnosis in resource-limited settings like Uganda. Although surgically cured locally, the patient's large tumor size and age confer a high risk for future metastasis, mandating rigorous, long-term surveillance.