Ossifying fibromyxoid tumor of soft parts: report of a case with novel cytogenetic findings

A slowly growing tumor of the left thenar region in a 40-year-old man had the classic features of an ossifying fibromyxoid tumor of soft parts, including an incomplete shell of lamellar bone; a center composed of nodular aggregates of small spindled, oval, and stellate cells in abundant myxoid stroma; and strong expression of vimentin, S-100, and neuron-specific enolase by the tumor cells. Clonal chromosomal abnormalities included loss of a chromosome 6, extra material of unknown origin attached to the long arm of chromosome 12, and an unbalanced translocation involving the short arm of a chromosome 6 and the long arm of a chromosome 14. The karyotype was interpreted as 45,XY, der(6;14)(p10;q10),add(12)(q24.3). The chromosomal abnormalities suggest osteochondroblastic rather than neuronal or schwannian lineage.