USP6 GENE REARRANGEMENT TESTING OF GNATHIC ANEURYSMAL BONE CYSTS: A MULTICENTER ANALYSIS OF TEN CASES

Abstract

Background The jaws are an uncommon location for primary aneurysmal bone cysts (ABCs), and few gnathic cases have been tested for USP6 rearrangement. Rearrangements of CDH11 and/or USP6 are identified in approximately 70% of primary extragnathic ABCs. MATERIALS/METHODS Herein, this multi-institutional, IRB-approved study investigates the USP6 status and clinicopathologic characteristics of cases histopathologically diagnosed as primary gnathic ABC. This study retrospectively identified 11 cases from four Oral & Maxillofacial Pathology Services and submitted them for USP6 analysis. Evaluation of one case failed, but the results of FISH testing, histomorphology, patient age and sex, lesion location, lesion duration, and clinical impression were abstracted for the remaining 10 cases. Results The patients ranged in age from 10 to 43 years (mean: 25.4 years), with a male-to-female ratio of 1:1 (5:5). Nine cases occurred in the mandible and one case in the maxilla. The majority of lesions were present for an unknown duration or more than one month. Morphologically, five cases exhibited classic ABC features while five exhibited few cystic spaces with “solid” morphology. None of the tested cases demonstrated rearrangement of the USP6 locus by FISH. Conclusion In the jaws, lesions that morphologically mimic primary extragnathic ABC rarely show USP6 abnormalities, and may be genetically distinct lesions. Lesions with USP6 rearrangement are neoplastic; however, the etiology of lesions lacking rearrangement is less certain and may represent primary ABC without USP6 rearrangement, secondary ABC that have effaced the lesion of origin, or ABC-like degenerative lesions.