Unusual presentation of dermatofibrosarcoma protuberans of the thigh: a case report.

Introduction and importance: Dermal fibroblasts can develop into dermatofibrosarcoma protuberans (DFSP), a rare low-grade sarcoma that grows slowly, is locally invasive, and has a high recurrence rate. Usually, it affects the proximal extremities or trunk. In contrast to its more typical occurrence on the trunk and proximal upper limbs, lateral thigh DFSP is highly unusual and may resemble benign entities such as lipomas, dermatofibromas, or pigmented nevi. Since DFSP on the lateral thigh is rare, diagnosis and treatment may be delayed because it could be confused with benign lesions. By highlighting this rare thigh presentation in a young adult, we aim to raise clinical awareness of DFSP's varied manifestations and underscore the value of early histopathologic evaluation. This could ultimately reinforce the need for wide excision to minimize recurrence. Case presentation: Initially believed to be a mole, a 24-year-old Pakistani woman appeared with a pigmented lesion on her right lateral thigh that was gradually growing. It grew in size over the course of 3.5 years with only minor discomfort. An examination showed a pigmented lesion that was hard and fixed. In line with DFSP, an excisional biopsy revealed a spindle cell tumor with a storiform morphology and diffuse CD34 positivity. Due to the narrow margins, a broad local excision with 2 cm margins was made. Postoperative recovery was complicated by a superficial wound infection, which resolved with antibiotics. Metastasis was not detected by follow-up imaging. The patient was still functionally intact and free of recurrences at 3 months. Clinical discussion: This example demonstrates the difficulties in diagnosing DFSP in unusual settings. Histopathology and immunohistochemistry are necessary for an accurate diagnosis. The secret to lowering recurrence is surgical excision with distinct margins. Long-term monitoring is crucial. Conclusion: Even in uncommon locations like the thigh, DFSP should be considered in cases of chronic, atypical skin lesions. For the best results, interdisciplinary care, extensive excision, and early diagnosis are essential.