Age / Sex : 26 / M

Age / Sex : 26 / M

Chief complaint : Left inguinal mass

alveolar soft part sarcoma

Discussion

Findings:

Pre-contrast CT shows low attenuated soft tissue mass at left pectineus muscle extending upwards to anterior acetabulum with destruction of the bone. Strong enhancement of the mass is seen with prominent vascular structures in and around the mass.

 Chest PA reveals multiple lung nodules which suggest lung metastasis

Differential Diagnosis:

Synovial sarcoma, angiosarcoma, liposarcoma, MFH, hemangioma

Diagnosis:  Alveolar soft part sarcoma

Discussion:

 Alveolar soft part sarcoma is a rare soft tissue sarcoma of young adults. Most commonly it occurs in the thigh, but a wide variety of other sites have also been described.

Alveolar soft part sarcoma is a painless, slow growing mass, but metastases are often found at the time of excision of primary tumor. Common sites of metastases are lung, brain and skeleton.

CT of the alveolar soft part sarcoma usually shows low attenuated soft tissue mass which can have punctate calcification. Contrast enhancement is essential in the diagnosis of the tumor, because the vigorous enhancement of the mass and dilated early draining veins are readily seen on the contrast-enhanced CT.

Alveolar soft part sarcoma is T1 iso or high signal intensity/T2 high signal intensity mass with multiple peritumoral and intratumoral signal voids due to its hypervascularity on MR images. Avid enhancement is seen with Gadolinium contrast administration.

References:

1. Laffan EE, Ngan BY, Navarro OM, Pediatric soft-tissue tumors and pseudotumors: MR imaging features with pathologic correlation: part 2. Tumors of fibroblastic/myofibroblastic, so-called fibrohistiocytic, muscular, lymphomatous, neurogenic, hair matrix, and uncertain origin, Radiographics. 2009 Jul-Aug;29(4):e36. Epub 2009 May 15.

2. Daly BD, Cheung H, Gaines PA, Bradley MJ, Metreweli C, Imaging of alveolar soft part sarcoma. Clin Radiol. 1992 Oct;46(4):253-6.

3. Lorigan JG, O'Keeffe FN, Evans HL, Wallace S, The radiologic manifestations of alveolar soft-part sarcoma. AJR Am J Roentgenol. 1989 Aug;153(2):335-9.