Peripheral primitive neuroectodermal tumor (pPNET) - pelvis

Case contributed by Ammar Haouimi
Diagnosis certain


Chronic left pelvic pain.

Patient Data

Age: 50 years
Gender: Female

There is an osteolytic lesion of the left iliac bone with an enhancing soft tissue component measuring (6.5 x 6 x 5.2 cm), invading probably the gluteus minimus and iliacus muscles.

The rest of the CT exam was unremarkable.

On the MRI the soft tissue component elicits an isosignal to the muscles on T1, high signal on STIR with vivid heterogeneous enhancement on postcontrast sequences and restricted diffusion on DWI/ADC. The is an extension to the adjacent soft tissue structures mainly the gluteus minimus and iliacus muscles. No extension to the hip joint is seen.

Follow-up MRI, six months after chemotherapy showing a significant improvement with almost complete regression of the soft tissue component. 

Case Discussion

A young adult was referred for with a solitary lytic lesion in the left iliac bone (with the suspicion of primary vs secondary tumoral process). All investigations were negative for metastatic disease.

A biopsy was performed with a histopathological exam which confirmed the diagnosis of a primitive neuroectodermal tumor.

Follow-up MRI six months after chemotherapy showed a significant improvement. 

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