Rare benign mesenchymal neoplasm: case report

Abstract

Objective: To report the clinical case of a patient with a typical clinical presentation and a histopathological diagnosis of dermatomyofibroma, a rare benign mesenchymal neoplasm. Case details: Female patient, 25 years old, attended the Dermatology outpatient clinic complaining of an asymptomatic, erythematous, brownish plaque, which had appeared 6 months before, located in the anterior region of the right shoulder. An incisional biopsy of the lesion was performed by punch, and the histopathological examination showed an absence of changes in the epidermis, proliferation of fibroblasts and collagen thickening, complemented by immunohistochemistry which was positive for cytoplasmic Beta Catenin and factor XIIIa, and negative for S100 and smooth muscle actin, compatible results of dermatomyofibroma. Final considerations: Dermatomyofibroma is a rare benign cutaneous mesenchymal neoplasm of myofibroblastic lineage with few cases reported in the literature so far. Its clinical form usually presents as a single plaque or nodule, asymptomatic, fibroelastic, poorly defined, with a brownish erythematous color. Immunohistochemistry helps in the diagnosis when the histological examination doesn’t define the disease, enabling the exclusion of possible malignant neoplasms with similar clinical presentations.