Frequency of USP6 rearrangements in myositis ossificans, brown tumor, and cherubism: molecular cytogenetic evidence that a subset of "myositis ossificans-like lesions" are the early phases in the formation of soft-tissue aneurysmal bone cyst.
OBJECTIVE
USP6 rearrangements with several partner genes have been identified recently in primary but not in secondary aneurysmal bone cysts (ABCs). Several lesions show histologic features that may overlap with ABC, including myositis ossificans (MO), brown tumor, and cherubism. The objective of this study was to assess whether these lesions harbored USP6 rearrangements.


METHODS
Twelve patients with classic radiologic and histologic features of MO, 6 with brown tumors, and 5 with cherubism diagnosed at our institution were studied for the presence of USP6 rearrangements using fluorescence in situ hybridization with probes flanking the USP6 locus on chromosome 17p13. In addition, conventional cytogenetic analysis was performed in 2 patients with cherubism.


RESULTS
USP6 rearrangements were identified in 2 patients with radiologic and histologic features consistent with MO. None of the patients with brown tumor or cherubism demonstrated USP6 rearrangements. Cytogenetic analysis of the cherubism patients demonstrated normal karyotypes.


CONCLUSIONS
These findings indicate that a subset of cases with apparent classic histologic and imaging features of MO are rather better classified as being soft-tissue ABC with clonal USP6 rearrangements. In contrast, no USP6 rearrangements were found in patients with cherubism or brown tumor, supporting the prevailing view that these lesions are distinct biologic entities.
Sukov
William R
WR
Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
Franco
Marcello F
MF
Erickson-Johnson
Michele
M
Chou
Margaret M
MM
Unni
K Krishnan
KK
Wenger
Doris E
DE
Wang
Xiaoke
X
Oliveira
Andre M
AM
D052437:Adipocytes, Brown / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D017824:Bone Cysts, Aneurysmal / Q000235:genetics*; D001859:Bone Neoplasms / Q000235:genetics*; D002636:Cherubism / Q000235:genetics*; D002648:Child; D002886:Chromosomes, Human, Pair 17; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D009221:Myositis Ossificans / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D012983:Soft Tissue Neoplasms / Q000235:genetics*; D043222:Ubiquitin Thiolesterase / Q000235:genetics*
D011518:Proto-Oncogene Proteins; C473330:USP6 protein, human; D043222:Ubiquitin Thiolesterase