Metastatic alveolar soft part sarcoma

Case contributed by Ammar Ashraf
Diagnosis certain


Irregular menstrual history with off and on pelvic pain for two years.

Patient Data

Age: 20 years
Gender: Female

A large complex predominantly solid hyper vascular mass, measuring 7 x 6 cm is seen in the right adnexa. 

A large, solid, lobulated, heterogeneously enhancing mass with central areas of necrosis arising from the retroperitoneal soft tissues in the right iliac fossa. This mass measures 12 x 12 cm and is extending inferiorly along the femoral vessels into the femoral triangle. Mass effect is seen on the iliac vessels and pelvic viscerae. Eroded medial cortical outline of the right iliac blade with a soft tissue mass involving the right iliac blade and roof of right acetabulum. A few small lymph nodes with the largest one measuring 8 mm are seen along the anterior aspect of the IVC & right common iliac artery at the L5 level; no other significant lymphadenopathy or abdominal visceral pathology is seen. Impression: Malignant looking right iliac fossa retroperitoneal soft tissue mass (soft tissue sarcoma?) with bone (local invasion of the right iliac blade) and pulmonary metastases (multiple bilateral lung nodules). 

Re-demonstration of an aggressive-looking sizable right iliac fossa soft tissue lesion with invasion of the right iliac bone on selected MRI images.


Nuclear medicine

Whole body, static and SPECT of the pelvis 3 hours after the injection (Tc-99m MDP).

Mild increased uptake in the right hemipelvis; the remaining skeleton shows physiological uptake. No other abnormal focus of isotope uptake.


Ultrasound guided tru-cut biopsy of the right pelvic mass lesion, done by the interventional radiologist. 

Case Discussion

Procedure: Ultrasound guided biopsy of the right iliac fossa mass. 

Microscopy: Sections from the pelvic mass shows a tumor with an organoid nesting pattern. The nests are separated by connective tissue containing sinusoidal vascular channels lined by flattened epithelium. The tumor cells are large polygonal with one or two vesicular nuclei with sharp cell borders. No mitosis is seen. Vascular invasion is not identified. PASD stain highlights the rod-shaped intracytoplasmic crystals.

Immunohistochemistry: Positive Myo D1 (5.8A) and Vimentin (V9). Focal positive Desmin (DE-R-11).  Negative CD10 (56C6), Calretinin (DAK-Calret 1) and CD56 (1B6). SMA (1A4): Highlights the vascular pattern.

Diagnosis: Alveolar soft part sarcoma.

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