Evaluation and Management of Non-Pruritic Blanching Rash in Adults

Introduction to Differential Diagnosis

The British Journal of Dermatology suggests that a non-pruritic blanching rash in an adult can be caused by polycythemia vera, which can present with rash and aquagenic symptoms 3, 4
The British Journal of Dermatology also recommends checking for lymphoma, particularly Hodgkin lymphoma, though pruritus is more typical 3, 4

The British Journal of Dermatology recommends a complete blood count with differential to assess for elevated hemoglobin/hematocrit, which suggests polycythemia vera, and lymphocytosis, which may indicate viral infection or lymphoma 3, 4
Iron studies, including ferritin, serum iron, and TIBC, should be checked in all patients with generalized skin manifestations, as both iron deficiency and overload can cause generalized rash 3, 4, 1
Liver function tests and renal function should be assessed, as hepatic disease and uremia are important causes of generalized rash 5, 1

The British Journal of Dermatology suggests that if a drug reaction is suspected, the suspected causative medication should be discontinued immediately, and non-sedating antihistamines, such as loratadine 10 mg daily, may be considered even without pruritus 5, 2
If systemic disease is identified, treatment of the underlying condition is essential for resolution, and for polycythemia vera, aspirin 300 mg daily may help associated symptoms 3
The British Journal of Dermatology recommends monitoring for evolution of rash, reassessing in 48-72 hours if diagnosis is unclear, and considering dermatology referral if rash persists beyond 2 weeks or diagnosis remains uncertain 2, 3, 4