A clinical, histologic, and molecular study of 9 cases of congenital dermatofibrosarcoma protuberans.

Background: The diagnosis of dermatofibrosarcoma protuberans (DFSP) in childhood is often difficult because of the deceptive appearance of the lesions. Little is known about congenital DFSP, the frequency of which is probably underestimated because the initial lesion may pass unnoticed.

Observations: We studied 9 DFSP congenital cases (8 plaques and 1 nodule) initially suspected to be benign lesions. The first biopsies or excisions were performed after a delay of 5(1/2) months to 15 years. All cases were CD34+. Histologic patterns were similar to the DFSP adult classic pattern in 4 cases. One case was a Bednar tumor. The histologic diagnosis of the 4 remaining cases was difficult. The collagen, type I, alpha 1-platelet-derived growth factor beta fusion gene (COL1A1-PDGFB) was detected by means of reverse transcriptase-polymerase chain reaction or fluorescence in situ hybridization.

Conclusions: All cases of congenital DFSP were difficult to identify clinically. The diagnosis was suspected by means of histologic and immunohistochemical evaluation and was confirmed using molecular analyses. This study illustrates the difficulties and pitfalls of the recognition of congenital DFSP and emphasizes the value of immunohistochemical study with anti-CD34 and complementary molecular analysis for all cutaneous spindle cell tumors and plaques in neonates and infants.