Pruritis Differential Diagnosis

The differential diagnosis for pruritis is broad and can be categorized based on the likelihood and potential impact of missing a diagnosis. Here's a structured approach:

• Single Most Likely Diagnosis
  • Dry Skin (Xerosis): This is often the most common cause of pruritis, especially in older adults or during dry weather conditions. It's a benign condition but can significantly affect quality of life.
• Other Likely Diagnoses
  • Atopic Dermatitis (Eczema): A chronic condition characterized by itchy, inflamed skin. It's common in children but can occur at any age.
  • Allergic Contact Dermatitis: An allergic reaction to substances like metals, latex, or certain chemicals, leading to itchy skin.
  • 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): Itchy welts that can appear anywhere on the body, often due to an allergic reaction.
• Do Not Miss Diagnoses
  • Hodgkin Lymphoma: Though rare, pruritis can be an early symptom of Hodgkin lymphoma, making it crucial not to miss this diagnosis.
  • Cholestasis: Pruritis can be a symptom of liver disease, including primary biliary cirrhosis or primary sclerosing cholangitis, where bile flow is reduced or blocked.
  • Thyroid Disorders: Both hyperthyroidism and hypothyroidism can cause pruritis, though the mechanism is not fully understood.
  • Renal Failure: Uremic pruritus is a common symptom in patients with chronic kidney disease or those undergoing dialysis.
• Rare Diagnoses
  • Polycythemia Vera: A rare blood disorder that can cause pruritis, especially after warm baths or showers.
  • Neurological Disorders: Certain conditions like multiple sclerosis, neuropathy, or neurodegenerative diseases can cause pruritis due to nerve damage.
  • Parasitic Infestations: Such as scabies or lice, which can cause intense itching.
  • Malignancies: Besides Hodgkin lymphoma, other cancers like leukemia or lymphoma can cause pruritis, though this is less common.

Each of these diagnoses has distinct characteristics and associated symptoms that can help guide the diagnostic process. A thorough history, physical examination, and sometimes laboratory tests are necessary to determine the underlying cause of pruritis.