iv: Alveolar Soft Part Sarcoma


This is a rare tumour, typically of adolescents and young adults (15-35 years).


In children, the tumour often arises in the head and neck, including the orbits.
In adults the tumour most commonly arises in the extremities.

Natural History

The tumour is usually painless and slow growing. Metastases develop early in the course (lung/brain) and may be the presenting finding.

Clinical Presentation

The highly vascular nature of this tumour may cause it to pulsate visibly.

Tumour/Normal Tissue Features

The tumour is soft and grey in colour. Haemorrhage/necrosis may be present.
The microscopic appearance is virtually diagnostic. The cells are arranged in nests surrounded by sinusoidal vascular channels. The cells in the nests are large and have eosinophilic cytoplasm with well defined cell borders. Central necrosis inside the nests can give an alveolar appearance. Anaplastic features are rare.
There is a charateristic chromosomal abnormality, known as derivative chromosome 17, which contains a translocation of chromosome 17 and X. This produces an abnormal transcription factor.

Staging / Classification

TNM or other staging system if relevant