Track: Case Reports

Abstract:

Dermatofibrosarcoma protuberans (DFSP) is a superficial, locally aggressive, low-grade fibroblastic neoplasm. Fibrosarcomatous transformation is associated with an increased risk of metastasis; however, neuronal differentiation in DFSP is rarely reported, and its clinical significance remains largely unknown. Here, we present a case of a 38-year-old female with a whitish, tender plaque on the central lower abdomen, present for at least 10 years. Histopathologic examination of a punch biopsy specimen revealed a spindle cell neoplasm with a biphasic appearance: (1) a more characteristic, cellular subcutaneous component of DFSP infiltrating the subcutis in a honeycomb pattern, and (2) a hypocellular dermal component histologically reminiscent of a neural neoplasm. Immunohistochemical staining showed that tumor cells in both the dermal and subcutaneous components were strongly and diffusely positive for CD34. Notably, a minor subset of CD34-positive cells, evenly scattered within the dermal portion, also expressed S100 and SOX10—a feature absent in the infiltrative subcutaneous component. Fluorescence in situ hybridization demonstrated a PDGFB gene rearrangement. The constellation of histomorphologic and molecular findings supports the diagnosis of DFSP. Follow-up abdominal MRI at two months showed no lymphadenopathy or additional lesions. This case highlights a rare variant of DFSP with dermal features resembling a neural neoplasm, potentially associated with indolent clinical behavior. We hope that this case will raise awareness of pathologists to consider this unusual neuronal differentiation, which is important to avoid misdiagnosis when evaluating DFSP.