Painful nodules on the soles in a 9-year-old boy

A 9-year-old child was referred to our paediatric dermatology unit for a temporary walking impairment because of painful lesions on the soles of both his feet. The lesions had erupted the day before, after prolonged walking with rubber boots. Physical examination showed multiple, reddish to purple, non-confluent, painful nodules on the soles of both feet (figure 1). The child was in general good condition, without fever. The laboratory tests performed (complete blood count, erythrocyte sedimentation rate, serum reactive protein, antinuclear antibody) were within normal limits. Histological examination showed a dense neutrophilic infiltrate around and within the eccrine cells. The diagnosis of palmoplantar eccrine hidradenitis (PEH) was made.1 PEH is an uncommon condition described for the first time in 1988 by Metzker and Brodsky.2 PEH is a self-limited disease characterised by erythematous violaceous papules and nodules of abrupt onset on the soles of otherwise healthy children. It may rarely involve the palms. The nodules usually appear after intense physical activity and are so painful that they lead to a walking impairment.3 The pathogenesis of PEH remains obscure; physical activity and hyperhidrosis may play a role by occluding the ducts of eccrine glands and activating the inflammatory response.4 It is important to recognise this condition to avoid unnecessary therapy with antibiotic and anti-inflammatory drugs. PEH has a self-limiting course and abstention from physical activity and bed rest alone are the best treatment, leading to a complete regression of the lesions in about a week.5 Erythema nodosum and traumatic plantar urticaria are the main differential diagnoses.