Congenital atrophic dermatofibrosarcoma protuberans detected by COL1A1-PDGFB rearrangement.

Background: Atrophic variant of dermatofibrosarcoma protuberans (DFSP) is a distinct form of DFSP.

Case Presentation: Here, we report the case of a 19-year-old woman with a small congenital atrophic plaque on the right precordium. The lesion remained atrophic for more than 10 years. Several years earlier, a portion of the plaque became tuberous and enlarged. Physical examination revealed a 25 × 30 mm erythematous atrophic plaque surrounded by three hard, smooth, and orange-colored nodules of varying sizes on the right precordium, along with visible subcutaneous adipose tissue and cutaneous veins. Biopsy of the nodule and atrophic plaque revealed dense proliferation of spindle-shaped tumor cells from the dermis to the subcutaneous adipose tissue, and positive immunostaining for CD34 and vimentin in addition to negative staining for factor XIIIa and α-smooth muscle actin. Reverse transcription polymerase chain reaction (RT-PCR) of the tumor tissue revealed the presence of a COL1A1-PDGFB fusion gene. Thus, congenital atrophic dermatofibrosarcoma protuberans was diagnosed. No metastasis to the lungs or regional lymph nodes was found on magnetic resonance imaging. Wide local excision and split-thickness skin grafting was performed and neither recurrence nor metastasis has been observed for 5 years and 8 months since the surgery.

Conclusion: This case indicates that a congenital atrophic lesion could represent a quiescent phase of DFSP. Awareness of this rare condition can aid with early diagnosis and thereby improve the prognosis of DFSP.