Chronic Venous Insufficiency or Arterial Ulcer: This is often the most common cause of non-healing wounds, including those on the scalp, due to poor circulation which impairs the healing process.

Infection (Bacterial, Fungal, or Viral): Infections can significantly delay the healing of wounds by causing ongoing inflammation and tissue damage.
Trauma or Repeated Injury: Continuous trauma to the wound site can prevent the wound from healing properly.
Diabetes Mellitus: High blood sugar levels can impair wound healing through various mechanisms, including neuropathy, reduced blood flow, and increased susceptibility to infection.
Nutritional Deficiencies: Lack of essential nutrients such as vitamins C and A, zinc, and protein can hinder the wound healing process.

Skin Cancer (e.g., Squamous Cell Carcinoma, Basal Cell Carcinoma): Although less common, skin cancers can present as non-healing wounds. Missing this diagnosis could lead to significant morbidity and mortality.
Vasculitis: Inflammatory diseases affecting blood vessels can cause wounds that do not heal due to compromised blood supply.
Pyoderma Gangrenosum: A rare skin condition that can cause painful ulcers, which might be mistaken for other types of wounds.

Sarcoidosis: A condition that can cause skin lesions and ulcers, including on the scalp, which may not heal normally.
Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues, potentially leading to poor wound healing due to tissue fragility.
Malignant Wounds (e.g., Metastatic Disease): In rare cases, a non-healing wound could be a sign of an underlying malignancy that has metastasized to the skin.