Palmoplantar Keratoderma, Punctate Type Iii

Nomenclature

Stevens et al. (1996) classified this disorder as type III punctate PPK, type I being the Buschke-Fischer-Brauer disorder (see PPKP1A; 148600), and type II being porokeratosis punctata palmaris et plantaris (PPKP2; 175860). They noted that PPKP3 has also been called focal acrohyperkeratosis.

Clinical Features

Acrokeratoelastoidosis was first described and named by Costa (1953). Jung (1973) studied an extensively affected family. The palms and soles are primarily affected, but involvement may extend to the dorsum of the hands and feet in severe cases. The lesions are nodular and yellow with hyperkeratotic surfaces. The histology combines hyperkeratosis and disorganization of elastic fibers. No systemic manifestation has been detected. The differential diagnosis includes other forms of palmoplantar keratosis and palmoplantar xanthomata. Matthews and Harman (1977) observed the disorder in 2 brothers whose mother was also affected.

Fiallo et al. (1998) found that elastorrhexis was a feature of lesional skin as well as of apparently normal skin in a patient with AKE, suggesting that the disorder could be regarded as a generalized defect of elastic tissue that is limited to the dermis. It was not known why the lesions are predisposed to erupt on the margins of acral sites.

Inheritance

Stevens et al. (1996) indicated that PPKP3 is an autosomal dominant disorder.

Mapping

In a linkage study of the large kindred reported by Jung (1973), Greiner et al. (1983) found a suggestion of linkage of AKE to ACP1 (171500), JK (111000) and IGKC (147200). Although the lod scores did not reach the level of significance considered to be proof, the fact that all 3 of these markers are on 2p suggests that AKE may be there also. Maximum lod scores were as follows: with IGKC, 0.57 at theta 0.16; with ACP1, 0.18 at theta 0.22; with Jk, 0.11 at theta 0.31.