Phacomatosis Pigmentokeratotica: A Further Case without Extracutaneous Anomalies and Review of the Condition
ABSTRACT Epidermal nevus syndrome is the term for the association of an epidermal nevus and extracutaneous anomalies, including neurologic, ophthalmic, and skeletal defects. Epidermal nevus syndromes include different disorders that share the feature of mosaicism. Phacomatosis pigmentokeratotica (PPK) is a distinctive new epidermal nevus syndrome first described in 1996 characterized by the presence of multiple organoid nevi with sebaceous differentiation, a speckled lentiginous nevus, and skeletal and neurologic abnormalities. Only a handful of cases of PPK without extracutaneous manifestations have been reported. We report here an individual with PPK with only cutaneous signs and confirm this distinctive syndrome has two subtypes according to the presence or absence of extracutaneous involvement.
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ABSTRACT: There are several different types of epidermal nevi, including keratinocyte epidermal nevi, nevus sebaceous, nevus comedonicus, and Becker nevus. This article highlights the varied clinical and histologic features of epidermal nevi, discusses recent data on pathogenesis, and provides an update on treatment options. Syndromes associated with epidermal nevi also are described.12/2012; 1(4). DOI:10.1007/s13671-012-0025-7
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ABSTRACT: Phacomatosis pigmentokeratotica (PPK) is a rare syndrome defined by the association of an organoid nevus occasionally with sebaceous differentiation, a speckled lentiginous nevus, and other extracutaneous anomalies. A preterm male infant of only 830 g at 27 week gestational age had an organoid nevus showing sebaceous differentiation. Also, he had multiple speckled-lentiginous nevus. Correlating the observed clinical presentation with the histopathological findings, the diagnosis of PPK was established. There have been less than 10 cases of PPK without extracutaneous manifestation. We present an uncommon case of a preterm patient with PPK who had no extracutaneous abnormalities.Journal of Korean medical science 11/2012; 27(11):1444-6. DOI:10.3346/jkms.2012.27.11.1444
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ABSTRACT: Phacomatosis pigmentokeratotica (PPK) is a rare epidermal nevus syndrome characterized by the cooccurrence of a sebaceous nevus and a speckled lentiginous nevus. The coexistence of an epidermal and a melanocytic nevus has been explained by two homozygous recessive mutations according to the twin spot hypothesis, of which PPK has become a putative paradigm in man. However, the underlying gene mutations remained unknown. Multiple tissues of 6 patients with PPK were analyzed for the presence of RAS, FGFR3, PIK3CA and BRAF mutations using SNaPshot assays and Sanger sequencing. We identified a heterozygous HRAS c.37G>C (p.Gly13Arg) mutation in 4 patients and a heterozygous HRAS c.182A>G (p.Gln61Arg) mutation in 2 patients. In each case, the mutations were present in both the sebaceous and the melanocytic nevus. In the latter lesion, melanocytes were identified to carry the HRAS mutation. Analysis of various non-lesional tissues showed a wild-type sequence of HRAS, consistent with mosaicism. Our data provide no genetic evidence for the previously proposed twin spot hypothesis. In contrast, PPK is best explained by a postzygotic activating HRAS mutation in a multipotent progenitor cell that gives rise to both a sebaceous and a melanocytic nevus. PPK is, therefore, a mosaic RASopathy.Journal of Investigative Dermatology accepted article preview online, 21 January 2013; doi:10.1038/jid.2013.24.Journal of Investigative Dermatology 01/2013; 133(8). DOI:10.1038/jid.2013.24