Alveolar soft part sarcoma - right leg

Case contributed by Dr Whitney Boyce

Presentation

Right lower extremity pain with enlarging right ankle mass. The mass was originally identified at an outside hospital however the patient did not seek treatment. She presented to our hospital 5 years later with pain and progressive enlargement of the mass. No fever, chills, shortness of breath. No family history of cancer.

Patient Data

Age: 25
Gender: Female

RLE xray demonstrating distal fibular destruction with large soft tissue mass.

Nuclear medicine

Bone scan demonstrating uptake and bony destruction in the right lower extremity

Large, lobulated T2 hyperintense, T1 isointense, avidly enhancing soft tissue mass with areas of central necrosis along the lateral aspect of the distal right leg. Numerous signal voids represent large peritumoral feeding vessels. There is complete destruction of the distal fibula metadiaphysis. 

Numerous bilateral lung metastases are seen on CT. 

Pathology

The patient underwent amputation. Gross path demonstrated a large, fungating, fleshy, grey colored soft tissue mass involving the distal right lower extremity. It involved the fibula, deep soft tissues and skin. 

Slides show nests of large tumor cells with generous eosinophilic cytoplasm, arranged in the classic alveolar growth pattern. 

Case Discussion

This is a path-proven alveolar soft part sarcoma of the right lower extremity, with metastases to the brain and lungs at diagnosis. The patient underwent above knee amputation and did well post-operatively.

Alveolar soft part sarcoma is a very rare, highly vascular, deep soft tissue malignancy that is classically seen in young adults, with a slight female predilection. It accounts for <1% of all soft-tissue sarcomas. It most frequently arises from the lower extremities. Distant metastases at the time of diagnosis is a relatively common feature, with metastases often spreading to the lungs, bone and brain.

Imaging characteristics

On MRI, alveolar soft part sarcoma often presents as a large, highly vascular mass that is T1 isointense or slightly hyperintense and T2 hyperintense, with heterogeneous contrast enhancement. Associated vascular signal voids are common secondary to large peritumoral blood vessels.

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Case information

rID: 59432
Published: 20th Apr 2018
Last edited: 24th Apr 2018
Inclusion in quiz mode: Included
Institution: university of texas at houston

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