Phrynoderma: a manifestation of vitamin A deficiency?... The rest of the story.

Phrynoderma is a distinctive form of follicular hyperkeratosis associated with nutritional deficiency. Although originally thought to represent vitamin A deficiency, several studies have demonstrated multiple etiologies. Characteristic skin lesions are hyperkeratotic papules that first appear on the extensor surfaces of the extremities, shoulders, and buttocks. We report a 14-month-old boy with malnourishment and hyperkeratotic papules and plaques with histologic changes typical of phrynoderma. Despite an extensive evaluation, a specific nutritional deficiency was not identified. Phrynoderma is believed to be a manifestation of severe malnutrition, not necessarily accompanying low vitamin A levels. While the literature supports a link between phrynoderma and vitamins E, B, A, and essential fatty acids general malnutrition seems to be the strongest association. The clinical picture typically improves with enhanced nutritional status. Phrynoderma must be considered in the differential diagnosis in patients with extensor surface hyperkeratotic papules and plaques in the setting of malnourishment and should prompt the clinician to evaluate cell markers of nutritional status, not just vitamin A. We believe this patient exemplifies the conundrum that faces clinicians in evaluating patients with extensor surface predominant hyperkeratotic papules and plaques in the setting of malnourishment.