Linear Porokeratosis Associated with Disseminated Superficial Actinic Porokeratosis: A New Example of Type II Segmental Involvement

Abstract

The coexistence of linear porokeratosis (LP) and disseminated superficial actinic porokeratosis (DSAP) in a 3-year-old girl with a family history of DSAP is presented. Happle proposed loss of heterozygosity (LOH) to explain the origin of this unusual phenomenon. Homozygosity would explain why lesions in LP are far more pronounced than those of the associated heterozygous DSAP lesions. LOH would also explain the early age of presentation of the linear lesions, the family history of DSAP, and why LP cases are particularly prone to malignant transformation. This case is also important for molecular studies because of the presence of heterozygous and homozygous mutated cells in the same patient and the familial occurrence of the heterozygous form of the disease.

Development of Segmental Superficial Actinic Porokeratosis during Immunosuppressive Therapy for Pemphigus Vulgaris

“…Secondly, type 2 mosaics are characterized by loss of heterozygosity of genes involved in the pathogenesis of superficial actinic porokeratosis (7). Clinically, this manifestation is characterized by disseminated porokeratotic lesions at the predilection sites accompanied by segments with a more severe phenotype commonly following the lines of Blaschko, increased disease activity and increased risk for malignant transformation (8)(9)(10)(11). Based on the clinical appearance of disseminated lesions in a segmental appearance without a linear distribution, we propose in our case a type 1 mosaieism of DSAP.…”

Extensive unilateral hyperkeratotic plaques in a blaschkoid distribution

“…Porokeratosis is typically classified by its clinical appearance: porokeratosis of Mibelli (PM), disseminated superficial actinic porokeratosis (DSAP), porokeratosis palmariset plantaris disseminata (PPPD), porokeratosis punctata palmaris et plantaris (PPPP), linear porokeratosis (LP), and craniosynostosis, anal anomalies and porokeratosis (CAP) syndrome. PM, LP, PPPP and CAP syndrome may present in childhood, but only LP may be present at birth . Congenital LP lesions are localized or extensive, and are distributed along the lines of Blaschko.…”

Disseminated superficial actinic porokeratosis co-existing with linear and verrucous porokeratosis in an elderly woman: Update on the genetics and clinical expression of porokeratosis

“…Like the Hivnor data, 32 the genes coded for woundrelated and hyperproliferative keratins, S100 calcium binding protein family members involved in keratinocyte differentiation and genes mediating intercellular communication. 33 In summary, there are multiple potential loci for this autosomal dominant disorder with a variety of clinical manifestations, all similar under the 22 Zhang et al 23 DSAP2: Zhang et al, 23 Xia et al 24 DSAP3: Xia et al, 22 Xia et al, 24 14 Happle, 20 Happle 21…”

“…[7][8][9][10][11][12][13][14][15][16][17][18] When an individual has isolated linear porokeratosis, often there are family members with DSAP. 11,19 Our patient had DSAP on the distal extremities, linear porokeratosis on the lateral thighs, and verrucous porokeratosis on the buttocks and mons pubis.…”