A 71yearold woman with a twoyear history of a slowly deepening, asymptomatic depression on her right upper trunk was ultimately diagnosed with atrophic dermatofibrosarcoma protuberans (DFSP), a rare nonprotuberant variant of a locally aggressive skin malignancy. The lesion measured 1.5 cm × 0.8 cm, appeared reddishbrown with a violaceousgray border, and felt firm and infiltrated on palpation—a texture that belied its depressed appearance. Biopsy revealed epidermal atrophy, basallayer hyperpigmentation, and a thinned dermis diffusely infiltrated by bland spindle cells extending into the subcutis, with no notable mitotic figures or atypia. Immunohistochemistry was diffusely positive for CD34 and negative for S100, SMA, desmin, cytokeratin, and factor XIIIa, confirming the diagnosis.

Atrophic DFSP is easily mistaken for benign sclerotic or atrophic disorders such as morphea, atrophic scar, anetoderma, or lipoatrophy, yet it retains the potential for local recurrence if incompletely excised. Despite its bland histologic appearance and very low proliferative index, this variant demands complete surgical removal. The patient underwent Mohs micrographic surgery, achieving clear margins, and remained recurrencefree at six months. Mohs micrographic surgery is associated with lower recurrence rates compared with wide local excision—1.7 % versus 3.7 % in comparative studies and 1.5 % versus 9.4 % in noncomparative studies—and should be strongly considered when available. This case underscores that persistent atrophic plaques with a firm, infiltrated consistency warrant a low threshold for biopsy, as early recognition and complete excision are critical to prevent local relapse.

The work titled “Atrophic Dermatofibrosarcoma Protuberans Presenting as a Depression in the Lateral Right Upper Trunk” was published on Skin (published on August 14, 2026).
DOI:10.2738/SKIN.2026.0016