Differential Diagnosis for Pruritus without Rash

• Single most likely diagnosis
  • Dry skin (xerosis): This is a common condition that can cause pruritus without a visible rash, especially in older adults or during dry weather.
• Other Likely diagnoses
  • Atopic dermatitis (eczema) in a quiescent phase: Even when the skin appears normal, atopic dermatitis can cause pruritus.
  • Urticaria: Although typically associated with hives, some patients with urticaria may experience pruritus without visible lesions.
  • Psoriasis: In some cases, psoriasis can present with pruritus before the appearance of characteristic skin lesions.
  • Allergic contact dermatitis: Pruritus can precede the development of a rash in allergic contact dermatitis.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
  • Hematologic malignancies (e.g., lymphoma, leukemia): Pruritus can be an early symptom of these conditions.
  • Thyroid disorders (especially hyperthyroidism): Pruritus without a rash can be associated with thyroid dysfunction.
  • Cholestasis: Obstructive liver disease can cause pruritus due to the accumulation of bile salts.
  • Neurological disorders (e.g., multiple sclerosis, neuropathy): Certain neurological conditions can cause pruritus without a rash.
• Rare diagnoses
  • Polycythemia vera: A myeloproliferative disorder that can cause pruritus, often after hot showers.
  • Mastocytosis: A condition characterized by the accumulation of mast cells, which can cause pruritus.
  • Aquagenic pruritus: A rare condition where water exposure induces pruritus without a rash.
  • Paraneoplastic syndromes: Rarely, pruritus can be a paraneoplastic symptom of an underlying cancer.