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Summary: Basal cell carcinoma (BCC), which is relatively easy to diagnose in a clinical setting, is the most common malignant tumor in the skin. Conversely, a giant BCC, a tumor beyond 5 cm in diameter, is a rare disease. In particular, a giant BCC beyond 20 cm in diameter is called a super-giant BCC, which frequently invades into deeper tissues, including the dermis, bones, or muscles. Here, we present a case of a 71-year-old patient who was initially diagnosed with multiple traumas with a large periosteal defect of the head. The ulcer was surrounded by malodorous necrotic tissue and slough, and several bacteria that caused necrotizing fasciitis were detected. Mapping biopsies after extensive debridement yielded BCC, and therefore, he was finally diagnosed with a super-giant BCC. A careful consultation revealed a history of ulcer on the head after a head injury approximately 10 years ago. He underwent radical dissection including the external table of the skull, followed by a free latissimus dorsi muscle flap with a meshed split-thickness skin graft. Because of the slow and chronic development of a super-giant BCC, accurate diagnosis is often difficult. Careful attention should be paid in patients with long-sustained ulcers.

Deep skin wounds with periosteal defects, frequently caused by traffic accidents or radical dissection, are refractory. Transplant surgery is frequently performed, but patients are subjected to stress for long operation periods, the sacrifice of donor regions, or several complications, such as flap necrosis or intractable ulcers. Even if the defects are covered, a scar composed of fibrous tissue remains in the body, which can cause itching, dysesthesia, or repeated ulcers because of the lack of distribution of peripheral nerves or hair follicles. Thus, treatments with the aim of regenerating lost tissue for deep wounds with periosteal defects are needed. Here, we show that the use of gelatin sponges (GS), which have been used as haemostatic materials in clinical practice, allowed the regeneration of heterogeneous tissues, including periosteum, skin, and skin appendages, when used as scaffolds in deep wounds with periosteal defects in rats. Bone marrow transplantation in rats revealed the mechanism by which the microenvironment provided by GS enabled bone marrow-derived cells (BMDCs) to form a vascular niche, followed by regeneration of the periosteum, skin, or skin appendages such as hair follicles by local cells. Our findings demonstrated that vascular niche formation provided by BMDCs is crucial for heterogeneous tissue regeneration.