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Undifferentiated malignant round cell sarcoma

Case contributed by Shervin Sharifkashani
Diagnosis certain

Presentation

Large soft tissue bulge on right side upper eyelid and anterior temporal fossa and proptosis.

Patient Data

Age: 15 years
Gender: Male

Large expansile and destructive solid mass in the right orbital roof and frontal calvarium middle to temporal side and right orbital lateral wall extended within the related orbital cavity, lacrimal gland, and temporal fossa is seen. The mass has remarkable compression on related eye uveo-scleral layer and extraocular muscles and caused significant proptosis and hypotropia and partially encased right eye uveo-scleral layer on the temporal side. There is also pronounced intracranial extension of the mass.

Fibroconnective tissue infiltrated by clusters of malignant uniform small round cells with round nuclei, scant clear to eosinophilic cytoplasm, sheet-like growth pattern, and perivascular distribution separated by dense fibrous tissue in favor of undifferentiated malignant round cell sarcoma.

The report was prepared by Dr. Nozarian Zohre.

Case Discussion

The case illustrates undifferentiated malignant round cell sarcoma (USRCS) presenting as a large destructive mass lesion within the right orbital roof and lateral wall with intracranial extension. In this particular case, whole-body imaging was negative for any other focus of the tumor. This group of tumors is rare, highly malignant, poor prognosis, and usually affects both the soft tissues and bones. 

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