Alveolar soft part sarcoma-radiologic patterns in children and adolescents

Alveolar soft part sarcoma is a rare but highly malignant tumour and little is known about its radiologic pattern in children. To describe the radiologic features of alveolar soft part sarcoma in children and adolescents. We retrospectively analysed the clinical and imaging data of six children age 7-17 years at diagnosis, with histologically or genetically proven alveolar soft part sarcoma. The tumours were located deep within muscles of the limbs (n = 4), in chest wall muscle (n = 1) and in the orbit (n = 1). High-flow feeding arteries, large drainage veins and intense enhancement were consistent findings by all imaging modalities. At MRI, all tumours demonstrated high signal intensity on T2-weighted images and high or iso-intense signal on T1-W imaging compared to muscle. In tumours larger than 70 mm in one dimension (n = 3/6), large vessels converging toward the tumour centre led to a highly vascularised central stellar area pattern. Five children demonstrated synchronous (n = 4/5) and metachronous (n = 1/5) lung metastases. Alveolar soft part sarcoma should be suggested when a highly vascularised, intramuscular mass demonstrating large feeding and drainage vessels converging toward a central stellar area is seen in children, especially if synchronous lung metastases are present.