Malignant fibrous histiocytoma (MFH) or undifferentiated pleomorphic sarcoma (UPS) is a sarcoma capable of invading adjacent structures. It is a mesenchymal neoplasia that predominates in men between the sixth and seventh decades of life. It is located mainly in the lower limbs and may affect the head and neck, trunk, and retroperitoneum, presenting a tendency to recurrence and local metastasis. This report aims to present a case of MFH in the ankle of a 49-year-old woman with an adjacent bone invasion, which evolved with transtibial amputation. Clinical, radiological, histopathological, and therapeutic aspects were addressed, highlighting the importance of early diagnosis.

Keywords: Amputation; Malignant fibrous histiocytoma; Sarcoma

Malignant transformation of folliculitis decalvans (FD) into squamous cell carcinoma (SCC) is rare but relevant due to its aggressive clinical course. We report the case of a 53-year-old man, a Jehovah's Witness, with a long-standing history of FD who developed rapidly progressive metastatic scalp SCC. Due to refusal of surgery, cemiplimab monotherapy (a PD-1 inhibitor) was initiated, resulting in complete resolution of the neoplasm within 12 weeks. This case highlights the risk of malignant transformation in chronic inflammatory dermatoses and suggests cemiplimab as an effective treatment option for advanced SCC when surgical resection is not feasible.

Keywords: Carcinoma, Squamous Cell; Skin Ulcer; Alopecia; Immune Checkpoint Inhibitors; Cicatrix; Skin Neoplasms