A novel t(6;13)(q15;q34) translocation in a giant cell reparative granuloma (solid aneurysmal bone cyst)

Fusion of the Lumican (LUM) Gene With the Ubiquitin Specific Peptidase 6 (USP6) Gene in an Aneurysmal Bone Cyst Carrying a t(12;17)(q21;p13) Chromosome Translocation

BACKGROUND/AIM

Aneurysmal bone cyst is a benign bone lesion with a strong tendency to recur. The rearrangement of chromosome band 17p13/USP6 gene is now considered a characteristic genetic feature of aneurysmal bone cyst, with t(16;17)(q22;p13)/CDH11-USP6 as the most frequent chromosomal aberration/fusion gene. We report a novel variant translocation leading to a new fusion gene in an aneurysmal bone cyst.

MATERIALS AND METHODS

Genetic analyses were performed on an aneurysmal bone cyst found in the tibia of a child.

RESULTS

G-banding chromosome analysis yielded the karyotype 46,XX,t(12;17)(q21;p13)[5]/46,XX[2]. FISH analysis with a USP6 break-apart probe showed rearrangement of USP6. RNA sequencing detected LUM-USP6 and USP6-LUM fusion transcripts which were subsequently verified by RT-PCR/Sanger sequencing. The two genes exchanged 5'- non-coding exons. Thus, promoter swapping between USP6 and LUM had taken place.

CONCLUSION

We report a novel t(12;17)(q21;p13) chromosome translocation which gave rise to a LUM-USP6 fusion in an aneurysmal bone cyst.

Atypical Presentation of Giant Mandibular Aneurysmal Bone Cyst with Cemento-Ossifying Fibroma Mimicking Sarcoma

Aneurysmal bone cysts (ABCs) are an uncommon osteolytic intraosseous bone lesions. ABCs commonly involve metaphysis of long bones and are rarely diagnosed in craniofacial bones. The World Health Organization (WHO) designates ABCs as benign, but locally destructive, rapidly growing masses. ABC can be clinically misdiagnosed as a malignant tumor. In this article, we present a case of a 12-year-old female patient who presented to a maxillofascial outpatient clinic complaining of huge jaw swelling over the past 3 months, which was clinically suggestive of sarcoma. Few reported cases in the English literature describe ABC presented with huge rapidly growing mass causing destructive bony lesion that was clinically mimic sarcoma, which initiates this case report. We also discuss the most important pathologic differential diagnosis of tumors with malignant behavior and review the literature.

Giant cell reparative granuloma of the scapula: report of a case and literature review

Giant cell reparative granulomas (GCRGs) are non-neoplastic inflammatory lesions, usually observed in the maxilla, mandible or small bones of the hands and feet. These lesions present a wide range of morphology and the misinterpretation with other giant cell lesions can often occur. We report the case of a 47-year-old woman with GCRG in the left scapula, presenting some uncommon features: the location (scapula) and age at presentation, the lack of underlying bone disease such as Paget's disease or fibrous dysplasia, the large aggressive expansile aspect of the lesion. This was a therapeutic study, level IV (case series with no or a historical control group).

USP6-induced neoplasms: the biologic spectrum of aneurysmal bone cyst and nodular fasciitis

USP6 (also known as TRE17) is a ubiquitin-specific protease that was identified as an oncogene in transfection experiments with Ewing sarcoma DNA 2 decades ago. Until recently, little was known about USP6 function and mechanisms of oncogenic activation. The identification of USP6 fusion genes in aneurysmal bone cyst (ABC) and, more recently, in nodular fasciitis led to a better understanding of the pathogenesis of these lesions. Furthermore, the detection of USP6 genomic rearrangements or USP6 fusion genes may be used as a diagnostic tool for these lesions. In this review, we discuss the clinicopathologic features, molecular pathology, and pathogenesis of ABC and nodular fasciitis. We also discuss the possible line of differentiation of ABC and its relationship to nodular fasciitis and other lesions.

Giant cell tumor of the tendon sheath mimicking a primary intramedullary metatarsal tumor

Giant cell tumor of the tendon sheath (GCTTS) is one of the most common benign soft tissue tumors in the extremities, and is frequently associated with bone abnormalities. Although extrinsic bone erosion is the most common bone abnormality associated with GCTTS, intraosseous invasion of GCTTS occurs rarely and may mimic a primary bone tumor, making diagnosis more challenging. We report an unusual imaging presentation of GCTTS mimicking a primary intramedullary metatarsal tumor and review the literature on the frequency of bone involvement of GCTTS.