Abstract
The use of modeling substances, such as mineral oil, can trigger chronic inflammatory reactions with serious complications, including persistent ulceration. In rare cases, these lesions may undergo malignant transformation to aggressive cutaneous neoplasms, such as Marjolin ulcers. We present the case of a 55-year-old transgender woman with a history of mineral oil injection who developed a chronic leg ulcer that underwent malignant transformation, with histological confirmation of a well-differentiated squamous cell carcinoma. This case highlights the importance of close monitoring of chronic ulcers in this patient population and underscores the severe consequences of using unregulated modeling agents.