Idiopathic plantar hidradenitis: a neutrophilic eccrine hidradenitis occurring primarily in children

Neutrophilic eccrine hidradenitis (NEH) has been described in a variety of clinical settings but is most often seen in leukemic patients receiving chemotherapy. We have recently encountered 6 healthy individuals, of whom 5 were children, who developed NEH localized to the feet. The patients were from 9 to 21 years of age. The presenting complaint was rapid development of tenderness of the feet with varying degrees of morbidity. At clinical evaluation, tender, erythematous papules and nodules were confined to the feet, primarily the plantar surfaces. The major differential diagnoses were erythema nodosum and vasculitis. Laboratory studies were non-contributory. Histologically, the findings were generally similar to those of NEH with certain exceptions, most notably the absence of syringosquamous metaplasia and the presence, in most cases, of neutrophilic abscesses in eccrine coils. Inflammatory and degenerative changes involved primarily the eccrine duct (coiled and dermal), and tended to spare the secretory apparatus. Stains for microorganisms were negative. There were brief recurrences in some of the patients, but those followed over time have remained well. We suggest the term idiopathic plantar hidradenitis for this condition.