Phacomatosis pigmentokeratotica or the Schimmelpenning‐Feuerstein‐Mims syndrome?

Phacomatosis pigmentokeratotica was first identified in 1996 as a distinct type of the epidermal nevus syndrome 1. On the skin, it is manifested as a combination of the linear nevus sebaceous and the speckled lentiginous nevus, also known as nevus spilus. Other associated features reported in patients with phacomatosis pigmentokeratotica most commonly included skeletal or neurological abnormalities 2, 3. In turn, the linear nevus sebaceous is commonly observed as a part of the Schimmelpenning‐Feuerstein‐Mims syndrome (OMIM #163200), and the speckled lentiginous nevus – as the congenital melanocytic nevus syndrome (OMIM # 137550). Molecular basis of these syndromes is presented by mutations in different genes, but HRAS mutations have been recorded in both. Moreover, Groesser et al. 4 identified heterozygous HRAS mutations present both in the sebaceous nevus and in the speckled lentiginous nevus tissues of patients with phacomatosis pigmentokeratotica. The analysis of various nonlesional tissues showed a wild‐type sequence of HRAS, consistent with mosaicism 4. Thus, phacomatosis pigmentokeratotica can now be categorized as one of the phenotypes of Schimmelpenning‐Feuerstein‐Mims syndrome as well as a variation in the congenital melanocytic nevus syndrome 5. There have been described cutaneous abnormalities and extracutaneous defects in patients with the Schimmelpenning‐Feuerstein‐Mims syndrome. Mehregan and Pinkus 6 were first to outline the natural history of organoid nevi. The first stage is characterized by alopecia with absent or primitive hair follicles and numerous small hypoplastic sebaceous glands. At puberty, lesions become verrucous with hyperplastic sebaceous glands. Benign or malignant tumors develop at later stages. Schimmelpenning‐Feuerstein‐Mims syndrome is associated with variable abnormalities of the central nervous system, including mental retardation, as well as ocular anomalies and skeletal defects. Apparently, the extracutaneous defects noted in the congenital melanocytic nevus syndrome may differ noticeably from those typical of the Schimmelpenning‐Feuerstein‐Mims syndrome.