DNA copy number changes in tumors within the spectrum of cellular, atypical, and metastasizing fibrous histiocytoma.

Background: Cutaneous fibrous histiocytoma (FH) is a common mesenchymal neoplasm. Metastasis is rare, disproportionately occurring among the aneurysmal, cellular, atypical, and deep variants.

Objective: We determined whether DNA copy number changes occurred in atypical FH (AFH), and whether they were similar to those in metastasizing FH (MetFH) and benign cellular FH (CFH).

Methods: Five primary tumors of MetFH were evaluated by array-based comparative genomic hybridization analysis, with tissue from local recurrences and lung metastases in 2 and 2 patients, respectively. Seven indolent AFH and 5 CFH were identified for comparison.

Results: Substantial differences between the groups were found both in the frequency of chromosomal aberrations (higher among MetFH and absent or solitary in CFH) and array-based comparative genomic hybridization profiles (frequent gains of 7 and 8q and losses of Xq in MetFH; recurrent losses of chromosomes 9 and 22 in AFH; isolated loss of 5q and gain in chromosome 20 in 2 CFH). Fatal MetFH cases (2 of 5 cases) exhibited the highest rate of chromosomal aberrations.

Limitations: This study included a small sample size with a short-term follow-up.

Conclusions: Benign CFH, indolent AFH, and MetFH represent distinct biological entities within the spectrum of FH; array-based comparative genomic hybridization may be a tool in recognizing FH cases with metastatic potential and increasingly aggressive behavior.