Differential Diagnosis for Generalized Itching

• Single most likely diagnosis
  • Dry skin (xerosis): This is often the most common cause of generalized itching, especially in older adults or during dry weather conditions. It's a benign condition but can be very uncomfortable.
• Other Likely diagnoses
  • Atopic dermatitis (eczema): A chronic skin condition characterized by itchy, inflamed skin. It's common in individuals with a history of allergies or asthma.
  • Psoriasis: An autoimmune condition that speeds up the life cycle of skin cells, causing cells to build up rapidly on the surface of the skin. The extra skin cells form scales and red patches that itch or burn.
  • Urticaria (hives): Often caused by an allergic reaction, urticaria can lead to itchy welts on the skin.
  • Allergic contact dermatitis: A type IV hypersensitivity reaction that occurs after exposure to an allergen, leading to itchy, inflamed skin.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
  • Hematologic malignancies (e.g., lymphoma, leukemia): Some cancers can cause itching due to the release of substances that stimulate nerve endings in the skin.
  • Liver disease (e.g., primary biliary cirrhosis): Itching can be a symptom of liver disease due to the buildup of bile salts in the skin.
  • Thyroid disorders (e.g., hyperthyroidism): Some thyroid conditions can cause itching, possibly due to increased sensitivity of the skin.
  • Kidney disease: Itching can be a symptom of kidney failure, possibly due to the buildup of toxins in the body.
• Rare diagnoses
  • Polycythemia vera: A rare blood disorder that can cause itching, especially after warm baths or showers.
  • Neurological disorders (e.g., multiple sclerosis, neuropathy): Some neurological conditions can cause itching due to nerve damage or dysfunction.
  • Mastocytosis: A rare condition characterized by an accumulation of mast cells in the skin, leading to itching and other symptoms.
  • Cholestasis of pregnancy: A condition that occurs in some pregnant women, causing itching due to bile duct obstruction.