Diffuse palmoplantar keratoderma Flashcards
(17 cards)
What are the two subtypes of PPK?
Epidermolytic PPK (E-PPK) and Nonepidermolytic PPK (NE-PPK)
E-PPK is also known as Vörner type.
What type of inheritance is associated with E-PPK, what is the mutation?
Autosomal dominant
E-PPK is due to keratin mutations—KRT9 and KRT1—on chromosomes 17q21 and 12q13 respectively.
What mutations cause NE-PPK?
AQP5 mutations on 12q13
NE-PPK is less common and can be autosomal recessive or dominant.
What is the incidence of E-PPK?
1:50,000
E-PPK due to KRT9 is the most common inherited PPK.
What is the age at presentation for PPK?
Shortly after birth to 1 year old
What is the pathogenesis of E-PPK?
Keratin mutations (KRT 9, 1) disrupt keratin filament assembly in suprabasal palmoplantar skin; hyperkeratosis compensates for damaged skin.
What is the pathogenesis of NE-PPK?
AQP5 mutation disrupts the aquaportin-5, water channel expressed in exocrine glands, water follows channels into skin -> hyperhidrosis,
How do KRT1 mutations compare to KRT9 mutations?
KRT1 mutations are milder than KRT9 mutations.
What are key features of the skin in PPK?
Diffuse to confluent, bilateral, symmetric, yellow-brown hyperkeratosis of palms and soles with well-demarcated erythematous border.
Usually no transgrediens; secondary painful fissuring, dermatophytosis.
What is a possible musculoskeletal feature of PPK?
Abnormal gait secondary to pain.
What are some differential diagnoses for PPK?
- Other genetic forms of PPK (focal or punctate)
- Pachyonychia congenita
- Syndromic PPK (WNT10A mutation with ectodermal dysplasia)
- Papillon-Lefèvre syndrome
- Acquired PPK
What laboratory data is associated with NE-PPK?
Skin biopsy shows orthokeratosis.
What is the laboratory finding for the Vörner variant?
Epidermolytic hyperkeratosis.
What management strategies are recommended for PPK?
- Referral to dermatologist for topical emollients and keratolytics
- Avoid oral retinoids in E-PPK
- Topical and oral antifungals
- Bath PUVA has helped some patients
What is the prognosis for individuals with PPK?
Persists throughout life; normal life span.
What are the clinical features of NE-PPK?
hyperhidrosis +/- bromhidrosis, pitted keratolysis, bacterial/fungal superinfection more likely with AQP5 mutation.
WHat clinical feature are more common with KRT1 mutations?
Keratotic papules affecting the dorsal hands, feet, knees , elbows, volar wrists
