Solar (brachioradial) pruritus--response to capsaicin cream

Solar (brachioradial) pruritus is an enigmatic condition affecting the lateral aspects of the arm(s) and is primarily seen in Caucasian people living in the tropics or subtropics.

Over a 5-year period we prospectively evaluated 68 patients with solar pruritus seen in an outpatient dermatology clinic. Clinical, biochemical, and microscopic and ultramicroscopic studies were performed. An open-label trial of capsaicin cream application was initiated in 15 patients.

An almost equal number of men and women were seen with an average age of 44 years. Brown-eyed and blue-eyed patients were seen with equal frequency. Most patients (86%) had outdoor occupations or avocations. The pruritus was intense, usually bilateral (72%) and invariably affected the lateral (as opposed to medial) aspects of the arm(s) in the absence of primary lesions. The most commonly affected area was the elbow area superficial to the brachioradialis and extensor carpi longus muscles, but extension of the pruritus to include the forearm and/or upper arm was common. Biopsy specimens (stained with hematoxylin and eosin) were normal or showed mild actinic elastosis in 15 patients tested. Ultramicroscopy showed myelin sheath splitting in all four patients studied. This is a nonspecific finding that may also be found in diabetic or alcoholic neuropathy. Ten of thirteen patients completing the capsaicin-cream study found significant relief (itching much improved or gone) after 3 weeks compared with the untreated control arm.

The cause of solar pruritus remains unknown, but circumstantial evidence implicates chronic exposure to solar radiation. Capsaicin may offer relief to these patients, but the patients need to be cautioned about the burning sensation that occurs with capsaicin cream.