Lithium-induced follicular hyperkeratosis.

A wide range of cutaneous reactions have been described in association with lithium therapy. Follicular eruptions have been noted briefly, but are not well documented in the dermatological literature. We report a 68-year-old man who developed a florid erythematous follicular eruption on the extensor surfaces of the limbs, with macular truncal erythema 6 months after commencing lithium therapy. His blood lithium levels were within the therapeutic range and there was no clinical evidence of lithium toxicity. Histology of lesional skin showed perifollicular inflammation and follicular plugging. The eruption improved on drug withdrawal. The cutaneous reactions to lithium and possible pathogenic mechanisms are discussed.