111 Primary Intracranial Ewing Sarcoma of the Mastoid Bone Mimicking an Inflammatory Process in a 5-Year-Old. (11th January 2018)

• Record Type: Journal Article
• Authors: Khurram, Nigar; Banihashemi, Amir; Shao, Charles
• Is Part Of: American journal of clinical pathology. Volume 149(2018)Supplement 1
• Page Start: S47
• Page End: S48
• Publication Date: 2018-01-11
• Subjects: Diagnosis, Laboratory -- Periodicals; Pathology -- Periodicals; 616.07
• DOI: 10.1093/ajcp/aqx118.110
• Languages: English
• ISSNs: 0002-9173

Abstract

Abstract: Ewing sarcoma (ES) family of tumors (EFTs) of the head and neck are rare and account for only 1% to 4% of all EFTs. The head and neck is rarely involved as the primary site; an even rarer subset of EFTs is the ES involving the mastoid bone, for which there are only two reported cases based on our review of the world literature. A 5-year-old boy presented with fever and rapidly enlarging painful mass over the right mastoid region complicated by frontal headaches, right ear pain, and decreased hearing on the right side. The mass over the mastoid region measured 4.0 x 6.0 cm, and was hard, non-erythematous, and tender to palpation. MRI revealed lentiform epidural fluid collection with thick peripheral enhancement extending along the margins of mastoid into the right middle and posterior cranial fossa. Pathological evaluation showed small round blue cell proliferation embedded in fragments of trabecular bone. The tumor cells show patchy granular positivity for CD99. Periodic acid-Schiff (PAS) and PAS-D stains show glycogen granules in tumor cells. Tumor cells were negative for AE1/AE3, CD45, and desmin. Fluorescence in situ hybridization analysis confirmed that tumor cells are positive for EWSR1 gene rearrangement at chromosome 22q12. The EFT is a high-grade tumor, with local invasion and a strong tendency to metastasize. Identification of molecular characteristics of the ES/PNET family has contributed to clinical care by providing a greater degree of confidence for an often difficult diagnostic problem. Further understanding of the basic mechanisms of these tumor-specific molecules has the potential to lead to novel therapies. Given its rarity for affecting the skull, particularly the mastoid bone, our findings add to our global understanding of this uncommon subset of patients affected by ES.