Approach and Work-Up for Medical Pruritus

Medical pruritus is characterized by itch secondary to systemic causes, which typically presents in the absence of primary skin lesions. Distinguishing medical pruritus from primary dermatologic pruritus on skin examination is challenging, given that some forms of dermatologic pruritus have very few or no primary lesions, or the primary lesions are obscured by secondary lesions. As a consequence of such diagnostic challenge, pruritus presentation often remains “idiopathic.” Unfortunately, underlying systemic diagnoses may be associated with significant morbidity and mortality, such as lymphoproliferative diseases or HIV infection. This highlights the importance of developing a systematic approach to patients presenting with medical pruritus. Therefore, patients presenting with generalized pruritus without primary skin lesions should be evaluated for systemic disorders through detailed patient history and physical examination, which could guide further laboratory investigations. If an underlying cause of pruritus is not identified, patients should be re-evaluated periodically with a review of systems and physical examination. The aim of this review is to discuss systemic causes of itch and propose a practical, evidence-based approach to the work-up of medical pruritus.