Trauma Injuries, burns, injections, decubitus, chilblains (pernio), neuropathic ulcers Infections Viral: herpes simplex virus, cytomegalovirus Bacterial: gangrene, ecthyma gangrenosum, ecthyma secondary to Staphylococcusaureus and/or group A Streptococcus; osteomyelitis, methicillin-resistant S. aureus Mycobacterial: Buruli ulcer (West Africa, Mycobacterium ulcerans), Bairnsdale ulcer (Australia, M. ulcerans), tuberculosis, leprosy Fungal: blastomycosis, coccidioidomycosis, paracoccidioidomycosis, chromomycosis, mucormycosis Spirochetal: syphilis, yaws Parasitic: leishmaniasis, amebiasis, schistosomiasis Bites Spiders, scorpions, snakes Metabolic Diabetes, gout, calciphylaxis (cutaneous necrosis from small- and medium-sized vessel calcification in diabetes, end-stage renal disease, or hyperparathyroidism) Vascular Venous: varicose veins, venous insufficiency Arterial: hypertension, arterial insufficiency, thrombosis, embolism Vasculitis Polyarteritis nodosa, vasculitis, collagen vascular disease, Behçet's syndrome Malignancy Cutaneous: squamous cell carcinoma, basal cell carcinoma Lymphoma: T-cell or B-cell lymphoma Hematologic Polycythemia, sickle cell anemia Dermatologic Bullous pemphigoid, necrobiosis lipoidica Drugs Hydroxyurea |