Sohn et al.1 reported the first case of dermatofibroma (DF) with sclerotic areas resembling a sclerotic fibroma (SF), in which transitional areas from DF to SF could be detected. A 55-year-old Japanese female presented with a domeshaped, firm, light-brown nodule, measuring 3 mm in diameter on the abdomen (Fig. 1A). The surface of the nodule revealed a hypopigmented pinkish area in the center (Fig. 1A). Dermoscopy showed a hypopigmented pinkish area with delicate reticulated vessels in the center (Fig. 1B, C), surrounded by brown pigmentation (Fig. 1C). She had no history of trauma. Histological examination demonstrated a relatively well-demarcated, non-encapsulated dermal nodule, the uppermost portion of which transitioned into an oval, eosinophilic area directly below the attenuated epidermis (Fig. 2A). The non-encapsulated dermal nodule was composed of spindle cells and collagen bundles in a vague storiform arrangement, consistent with DF (Fig. 2B). The oval, eosinophilic area was composed of hypocellular hyalinized collagen bundles with prominent clefts (Fig. 2C). The arrangement was reminiscent of a storiform pattern (Fig. 2C). The histological findings were characteristic of SF. In the transition area, DF shifted gradually into SF (Fig. 2D). The overlying epidermis was attenuated right above the SF area, and was hyperplastic with basal hyperpigmentation in the periphery (Fig. 2E). Immunohistochemically, a few spindle cells in the DF nodule were positive for factor XIIIa and CD34 (Fig. 2F), contrary to the cells in the SF area.
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