Hereditary Papulotranslucent Acrokeratoderma: Prominent Clinical Presentation after Water Exposure.

Dear Editor:

Hereditary papulotranslucent acrokeratoderma (HPA) was first described in 1973 by Onwukwe et al.1 It is a rare autosomal dominant disease characterized by asymptomatic, persistent, white-yellow translucent papules on the palms and soles and is accentuated by aqueous exposure. HPA should be distinguished from aquagenic syringeal acrokeratoderma (ASA), in which a palmar rash after water exposure is noted.

A 44-year-old female presented with lesions on her palms and soles. The lesions had first appeared 30 years prior, after swimming. The lesions were not painful or pruritic and did not regress spontaneously. Notably, she stated that the lesions became more prominent when her palms were exposed to water. She claimed that her teenage son recently developed similar lesions.

On physical examination, numerous tiny flesh-colored papules were seen on her palms and soles. For diagnosis, we asked her to soak her left hand in lukewarm water for 10 minutes. The lesions immediately became distinguishable. One-to-three-millimeter sized papules were diffusely scattered on the palm and ulnar edge of the left hand (Fig. 1A, B), and the dorsal aspect was partially involved. Skin biopsy was performed on two lesions; center of the palm and ulnar edge of the left hand. Both specimens had hyperkeratosis, hypergranulosis, and acanthosis. There were no inflammations in the dermis or abnormality in adnexal structures (Fig. 1C, D).

Fig. 1

Clinical and histopathologic photographs. Clinical photographs of left palm (A) and ulnar edge of the left hand (B) after water exposure for 10 minutes. For diagnosis, skin biopsy was performed on the center of the left palm and ulnar edge of the left hand. Both specimens showed epidermal hyperkeratosis, hypergranulosis, and acanthosis, without dermal inflammation or changes of adnexal structures. These findings were more prominent in specimen of the center of the palm (H&E: C, ×40; D, magnified view of the red box in C, ×100).

HPA is a rare variant of punctate palmoplantar keratoderma (PPK)1. However, unlike punctate PPK, HPA may involve some part of dorsum and volar aspect of hands and feet, and the papular lesion does not fall off or leaves depression. The pathogenesis remains uncertain2. It usually manifests in adolescence to mid-adulthood. Water exposure exacerbates the lesions. Marked hyperkeratosis, hypergranulosis and acanthosis are typical histopathological characteristics. No significant inflammation or changes in elastic fiber and adnexal structure are observed1.

HPA shares similar characteristics, including onset, distribution, and reaction to water exposure, with ASA3. However, ASA is reported as acquired and most significantly, it has transient symptomatic lesions4. ASA presents “hand-in-the-bucket” sign, burning sensation and edema after water exposure5. Dilated sweat ducts are a characteristic histopathological finding distinguishing ASA from HPA.

In this case, it is difficult to precisely describe heredity. However, autosomal dominance can be presumed. Based on the clinical presentation demonstrating asymptomatic papular lesions accentuated by aqueous exposure and family history based on similar lesions in her son, and no significant change of the dermis in histopathologic findings, the patient could be diagnosed with HPA. As she presented with no specific symptoms, we prescribed topical urea and salicylic acid mixed cream for hyperkeratosis.

Satisfactory treatments for HPA have not been established. Due to its asymptomatic nature and no association with systemic diseases, it usually does not require treatment. Keratolytics including topical urea, salicylic acid, and ammonium can be used.

We report a case of HPA with a hereditary family history and characteristic lesions prominent after water exposure. We received the patient's consent form about publishing all photographic materials. We aim to create awareness among physicians regarding this rare, interesting, and distinctive disease.