Nine-Year Follow-Up of a Huge Retroperitoneal Alveolar Soft-Part Sarcoma: A Case Report

BACKGROUND Alveolar soft-part sarcoma is an uncommon mesenchymal tumor accounting for approximately 0.7% of soft tissue sarcomas in adults. It mainly affects young adults, with a peak incidence between 15 and 35 years old. Available data indicate that surgical resection with adjuvant therapy using tyrosine kinase inhibitor may be considered the standard treatment. The rarity of the disease and resultant data scarcity makes it difficult to establish treatment guidelines. CASE REPORT We present the 9-year follow-up of a 24-year-old patient with an initially advanced (stage IV), huge, 21-cm alveolar soft-part sarcoma of the retroperitoneum. During the observation period, the patient developed pulmonary, brain, and bone metastases. In the course of treatment, she underwent excision of the main tumor, excision of satellite tumors, and brain metastasectomies, and was treated with sunitinib, pazopanib, and radiotherapy. No similar case reports were found in the PubMed database. CONCLUSIONS Our multimodal approach resulted in a long period of stable disease. Late progression may occur; therefore, frequent and thorough imaging evaluation of such patients is crucial. Our case is one of the largest ASPS tumors reported, and her long-term successful treatment makes this report valuable, considering the scarcity of data regarding treatment of ASPS. Further large-cohort, multi-center studies are necessary to establish the best treatment.