A rare cutaneous neoplasm - Dermatomyofibroma

Abstract

Background: Dermatomyofibroma (DMF) represents a rare and distinct benign cutaneous mesenchymal neoplasm of fibroblastic/myofibroblastic differentiation. Approximately 150 cases of DMF have been documented in the literature. Nevertheless, the occurrence of DMF on the face is exceptionally rare. Clinically, DMF is often misdiagnosed as a scar, keloid or dermatofibrosarcoma protuberans. Thus, histopathological and immunohistochemical analyses are instrumental in establishing a differential diagnosis. We present a rare case of dermatomyofibroma that occurred in the facial region. Case presentation: A 20-year-old female patient presented to Sundara Dermatology Clinic in August 2025, with a lesion that had persisted for two years on her left masseteric region. Previously, she had consulted at the National Dermatology Center, where she was diagnosed with “acne scar” and underwent an intradermal triamcinolone injection once. However, the treatment proved ineffective, and the lesion gradually increased in size. Upon physical examination, a poorly circumscribed, irregularly elevated, firm, brown plaque measuring 2.5 x 2 cm in size was observed on the left upper chin, extending to the preauricular region. Diagnosis: A skin biopsy was performed to establish the diagnosis. Histopathological examination suggested differentiating Dermatomyofibroma from Dermatofibrosarcoma protuberans. Therefore, immunohistochemical analysis utilizing CD34 and SMA markers was conducted. Based on the histological and immunohistochemical findings, the final diagnosis was confirmed as Dermatomyofibroma. Treatment: The standard treatment for DMF is complete surgical excision of the tumor. After providing the patient with an accurate diagnosis and recommending surgical excision, she underwent a surgery and the tumor was completely excised. To date, no instances of recurrence have been noted. Conclusion: Dermatomyofibroma is a rare benign cutaneous neoplasm characterized by clinical features that overlap with other dermatological conditions, which increases the risk of misdiagnosis and inappropriate treatment. We emphasize the critical role of skin biopsy and immunohistochemical analysis in cases with similar clinical manifestations, thereby mitigating the risk of further misconduct.