Venous Insufficiency Ulcer: This is often the most common cause of recurrent non-healing skin ulcers, particularly in the lower extremities. Venous insufficiency leads to increased pressure in the veins, causing fluid leakage into the surrounding tissue, which can result in ulceration.

Diabetic Foot Ulcer: Individuals with diabetes are prone to developing foot ulcers due to neuropathy, which can lead to unnoticed injuries, and peripheral artery disease, which impairs healing.
Arterial Ulcer: Caused by poor circulation, these ulcers are often found on the lateral aspect of the leg and are associated with pain, especially at night.
Pressure Ulcer: Also known as bedsores or decubitus ulcers, these occur due to prolonged pressure on the skin, leading to tissue damage and ulceration.

Malignancy (e.g., Squamous Cell Carcinoma, Basal Cell Carcinoma): Although less common, skin cancers can present as non-healing ulcers. Missing a diagnosis of malignancy could have severe consequences.
Infectious Diseases (e.g., Tuberculosis, Leprosy): Certain infectious diseases can cause skin ulcers that do not heal, and missing these diagnoses could lead to significant morbidity.
Vasculitis: Inflammation of the blood vessels can cause skin ulcers, and some forms of vasculitis can be life-threatening if not treated promptly.

Pyoderma Gangrenosum: A rare skin condition characterized by the development of large, painful ulcers, often without a clear cause.
Ehlers-Danlos Syndrome: A group of genetic disorders affecting the body's connective tissue, which can lead to poor wound healing and the formation of ulcers.
Sickle Cell Ulcer: Individuals with sickle cell disease can develop ulcers, typically on the lower extremities, due to the sickling of red blood cells leading to vascular occlusion and tissue ischemia.