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(1;17)(p34;p13), a 7-year-old boy with a tumor located in the tibia (Althof et al., 2004; Oliveira et al., 2005).

Surgical curetage.

Recurrence occurs in one fourth of cases.

The t(1;17)(p34;p13) was the sole anomaly.

THRAP3 (thyroid hormone receptor associated protein 3)

1p34.3

THRAP3, also called TRAP150, is made of an arginine/serine-rich sequence in the N-terminal region and domains with similarity with BCLAF1 and with CASC3/MLN51 in the C-terminal region. It is part of the transcription regulatory complex TRAP/Mediator, and a component of the spliceosome. It both activates pre-mRNA splicing and induces mRNA degradation. The arginine/serine-rich N-term of THRAP3 is responsible for its splicing activity, and the C-term part for its mRNA degradation activity (Lee et al., 2010).

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 THRAP3 - 3 USP6

Fusion of the noncoding exon 1 of THRAP3 to a splicing variant of USP exon 1 (i.e. to the entire coding sequence of USP6, resulting in upregulation of USP6).