Howel-Evans syndrome - Skin
Patients present with tylotic changes (a thickening of the skin, or callus formation) of the palms and soles, typically over areas of pressure, in early youth. The hyperkeratotic changes may be confluent over the palms and soles or localized to the areas of pressure, such as the heels and forefeet. Painful fissures are a common complication. In general, the feet tend to be more severely affected, most likely because of increased mechanical pressure in this area. The hyperkeratosis does not extend to the dorsum of the acral areas.
Howel-Evans syndrome is thought to have two separate forms: type A syndrome and type B syndrome. In type A syndrome, the first signs of palmoplantar keratoderma (PPK) arise between ages 5 and 15, whereas in type B syndrome, PPK develops at birth or in the first years of life. In addition, in type B syndrome, PPK lesions are well demarcated and rarely complicated by painful fissuring. It is important to delineate the type of Howel-Evans syndrome presenting in individual patients, as it has prognostic significance: the associated malignancies are more common in type A syndrome.
There have been a number of cases of Howel-Evans with associated ectodermal abnormalities. These findings suggest that this syndrome may be a variant of ectodermal dysplasia and thus support its classification as palmoplantar ectodermal dysplasia type III. Other associations with this syndrome include bronchial carcinoma, esophageal strictures, squamous cell carcinoma of the skin, and gastric and laryngeal carcinoma.
Q82.8 – Other specified congenital malformations of skin
111030006 – Howel-Evans syndrome
- Mucosal hyperkeratosis syndrome – autosomal dominant (AD), white lesions of the gingiva, and PPK
- Focal PPK with oral mucosa hyperkeratosis – focal PPK, oral hyperkeratosis, subungual hyperkeratosis (mutation keratin 16)
- Pachyonychia congenita type I (Jadassohn-Lewandowsky syndrome) – AD, congenital pachyonychia, hyperhidrosis of the palms and soles, follicular keratosis, palmar and plantar, and leukoplakia of oral and anal mucosa
- Acrokeratosis neoplastica (Bazex syndrome)
- Acanthosis nigricans maligna
- Other keratodermas