Benign but locally aggressive tumor.

Occurs mainly in vertebrae and flat bones. Multiple involvement is frequent.

May involve the arrest of maturation of the osteoblasts caused by USP6 overexpression and dysregulation of autocrine BMP (bone morphology protein) signaling (Lau et al., 2010).

Usually seen in patients aged 10-20 years; represents about 5% of primary bone tumours; slightly more frequent in female patients.

Forms a spongy hemorrhagic mass; symptoms are pain, swelling, pathological fractures. One case to date was found with a t(9;17)(q22;p13), a 10-year-old boy with a tumor located in the clavicle (Oliveira et al., 2005). However, a malignant fibrous histiocytoma has also been described with a t(9;17)(q22;p13), as part of a complex karyotype (Sozzi et al., 1997).

Surgical curetage.

Recurrence occurs in one fourth of cases.

The t(9;17)(q22;p13) was the sole anomaly.

OMD (osteomodulin)

9q22.31

OMD (osteomodulin), also called OSAD (osteoadherin), is a member of the small leucine rich-repeat proteoglycan (SLRP) family. It is an extracellular matrix keratan sulfate proteoglycan restricted to mineralized tissues. OMD is a marker for terminally differentiated matrix producing osteoblasts. OMD expression enhances the differentiation and maturation of osteoblasts. It is induced by osteoclast activity (Rehn et al., 2008).

USP6 (ubiquitin specific protease 6 (Tre-2 oncogene))

17p13.2

USP6, also called TRE17/ubiquitin-specific protease 6 (USP6), is a deubiquitinase. It is the first de-ubiquitinating enzyme to activate NF-KB, and requires both catalytic subunits of IKK (IKKalpha and IKKbeta) (Pringle et al., 2011).

5 OMD - 3 USP6

Fusion of the noncoding exon 1 of OMD to a splicing variant of USP exon 1, resulting in upregulation of USP6.