Translocation t(2;11) is characteristic of collagenous fibroma (desmoplastic fibroblastoma).

Collagenous fibroma (desmoplastic fibroblastoma) is a rare, benign soft-tissue tumor composed of spindled and stellate-shaped cells embedded in a dense collagenous stroma. Recently, a translocation between chromosomes 2 and 11 or a rearrangement involving the chromosome 11q12 breakpoint was reported to be recurrent and unique in collagenous fibroma. Herein, we describe a case of collagenous fibroma arising in the left thigh of a 57-year-old man. Magnetic resonance imaging revealed a 5.5 cm soft-tissue mass deep relative to the vastus medialis with low signal intensity on both T1- and T2-weighted sequences. A marginal excision of the tumor was performed, and histopathologic features were consistent with collagenous fibroma. Cytogenetic analysis exhibited a reciprocal translocation involving the long arms of chromosomes 2 and 11. This finding suggests that the t(2;11) is likely to be of pathogenetic significance in a subset of collagenous fibromas.