Dermatofibrosarcoma protuberans / giant cell fibroblastoma

Dermatofibrosarcoma protubrans is a spindle cell tumour. A translocation between chromosomes 17 and 22 fuses the collagen type I alpha I (COL1A1) gene with the platelet-derived growth factor beta (PDGF-b) gene.

Immunohistochemistry

• CD34 positive

• Apo D positive

Differential diagnosis

• benign fibrous histiocytoma: tenascin stains both dermatofibroma and dermatofibrosarcoma protuberans: it is helpful in the differentiation because it forms a continuous strongly positive band at the dermo-epidermal junction overlying dermatofibroma but not dermatofibrosarcoma protuberans:

• benign neural tumours

• myxoid dermatofibrosarcoma protuberans may resemble myxoid liposarcoma

Cytogenetics

There are ring chromosomes characterised by a complex alternating translocation t(17;22)(q22;q13).

Prognosis

Ther are often multiple local recurrences.

References

1Kahn, H. J., Fekete, E., From, L. Tenascin differentiates dermatofibroma from dermatofibrosarcoma protuberans: comparison with CD34 and factor XIIIa. Hum Pathol 2001;32:50-56.

2Westra, W. H., Gerald, W. L., Rosai, J. Solitary fibrous tumor. Consistent CD34 immunoreactivity and occurrence in the orbit. Am J Surg Pathol 1994;18:992-8.

3West, R. B., J. Harvell, et al. (2004). "Apo D in soft tissue tumors: a novel marker for dermatofibrosarcoma protuberans." Am J Surg Pathol 28(8): 1063-9.

This page last revised 11.9.2004.