Botulinum toxin is helpful in aquagenic palmoplantar keratoderma

Sir, Patients with aquagenic palmoplantar keratoderma (APK) complain of discomfort and swelling of their hands after a few minutes' contact with water. Treatment options are limited. A 35‐year‐old woman presented with a 2‐year history of discomfort in her hands after 5 min of contact with water. Her hands would become white and wrinkled with white papules over the palms (Fig. 1). She also had an affected patch on her left foot but the rest of her skin was not involved. After removal of her hands from water, they returned to normal with a tight sensation approximately 30 min later. She had a history of axillary and palmar hyperhidrosis which were also evident on examination. There was no relevant family history. A skin biopsy was normal and screening for the common delta F508 cystic fibrosis gene mutation, and the other cystic fibrosis gene mutations which account for approximately 85% of northern European mutations, was negative. Over the next 6 months both feet became affected and the changes were occurring more often. A trial with aluminium chloride hexahydrate had been unsuccessful, and our patient was now minimizing all contact with water. Botulinum toxin (Botox®; Allergan, High Wycombe, Bucks, U.K.) injections were therefore considered. Following median and ulnar nerve blocks with 2% lignocaine, the left palm was injected at multiple sites with a total of 50 IU of botulinum toxin reconstituted in 2 mL of normal saline. Injections were placed immediately subdermally with a 30FG needle and 1 mL syringe. Within 7 days the patient started to notice a significant improvement. After immersion of her hands in water, she continued to experience tingling sensations along the radial and ulnar borders of her hands, beyond the areas treated with botulinum toxin. Minimal changes were evident on the left palm although the wrinkling and swellings were still prominent on the fingers, which had not been treated. Five months later, there was recurrence of her symptoms and the botulinum toxin injections were repeated. She also requested the same treatment for the right hand. (a) Comparison between affected and unaffected hand. (b) White pebbly appearance. Twelve cases of APK, also known as aquagenic keratoderma, aquagenic syringeal acrokeratoderma and transient reactive papulotranslucent acrokeratoderma, have been reported in the literature. It is an acquired keratoderma, initially described in 1996 by English and McCollough.1 They described two sisters with thickening of the palms with translucent papules and white discoloration after contact with water. The term ‘transient reactive papulotranslucent acrokeratoderma’ was used as the clinical appearances seen were similar to those in a patient described in 1973 who had a hereditary acral keratoderma with a history of ‘wrinkling’ of the palms on immersion in water, although this had subsequently resolved.2 In affected patients, the hands either look normal or there is hyperlinearity or papules with prominent eccrine ducts3, 4 prior to placement of hands in water. After 2–10 min of contact with water, patients complain of discomfort in their hands, and a whitish pebbly appearance is seen.5 These features are compatible with those seen after prolonged immersion of hands in water in normal individuals; however, in these patients they occur after only a few minutes. A tightening sensation is felt as the hands dry. The ‘hand‐in‐the‐bucket’ sign was coined by Yan et al.3 as patients commonly present with their hands in water in order to demonstrate the physical signs. Palmar hyperhidrosis has been reported in most cases and treatment options have mainly aimed at treating this.1, 3, 5–7 Skin histology of the palm may show prominent eccrine ducts and hyperkeratosis, although a normal biopsy may be obtained.7 Of the 12 cases in the literature, six had no histological assessment,3, 5, 8 five had dilated openings of the sweat glands1, 4, 6, 9 and one had normal histology.7 The pathogenesis of APK is unknown. Disorders of the stratum corneum,5–7 an aberration of the sweat glands4 and salt retention8 have been considered. It is interesting that quick generalized wrinkling of skin after immersion in water has long been recognized in cystic fibrosis.10 There is only one report of a patient with cystic fibrosis and APK and the authors felt that it was not clear whether this was a chance association.6 The common cystic fibrosis gene mutation was not present in our patient. Although we have not excluded bilateral mosacism for cystic fibrosis occurring in the hands this is extremely unlikely. Some cases of APK have cleared spontaneously after a few years. Treatment of the associated hyperhidrosis with aluminium chloride hexahydrate has produced variable results. In our patient, botulinum toxin injections were considered as they are a well‐established treatment for hyperhidrosis.11 We suggest that botulinum toxin injections may be a good treatment option for APK in patients with associated hyperhidrosis, but the long‐term effects of repeated injections have not yet been established. Conflicts of interest: none declared.