Epidermal nevus syndromes

[Benign skin neoplasms in children]

There are many different types of skin neoplasms in children and most are benign. Dermatologists should be able to differentiate between the various types of benign skin neoplasms and be able to recommend optimal treatment to concerned patients. Surgical removal of benign skin neoplasms is often the only treatment option. The aim of this paper is to provide a general overview of epidermal lesions (e.g., inflammatory linear verrucous epidermal nevus [ILVEN], nevus sebaceous), tumors of the epidermal appendages (e.g. pilomatrixoma), cutaneous neoplasms (e.g. angiofibroma), fibromatoses (e.g., knuckle pads), tumors comprised of fat, muscle, or bone tissue (e.g., osteoma cutis, subungual exostosis), epidermal cysts and pseudocysts, and pathologic fibrosis reactions after dermal injury (keloid). Scientific data are scarce and only in the last decade has it been possible to perform histopathological examinations and genetic studies together with detailed phenotyping to gain new understanding of the pathogenetic mechanisms.

Neuroimaging manifestations of epidermal nevus syndrome

Epidermal nevus syndrome (ENS) represents a diverse group of rare neurocutaneous diseases associated with the presence of characteristic epidermal nevi (EN) in the skin and extracutaneous manifestations in the eyes, skeletal, urogenital and central nervous systems. We present a case series of 7 children with ENS, with specific attention to the neuroradiological characteristics of this entity.

Epidermal Nevi and Related Syndromes -- Part 1: Keratinocytic Nevi

Epidermal nevi are hamartomatous lesions derived from the epidermis and/or adnexal structures of the skin; they have traditionally been classified according to their morphology. New variants have been described in recent years and advances in genetics have contributed to better characterization of these lesions and an improved understanding of their relationship with certain extracutaneous manifestations. In the first part of this review article, we will look at nevi derived specifically from the epidermis and associated syndromes.

Schimmelpenning Syndrome: An Association with Vascular Anomalies

Objective:

Schimmelpenning syndrome is a rare neurocutaneous disorder characterized by craniofacial nevus sebaceus in association with seizures, developmental delay, and ocular or skeletal pathology. Vascular anomalies also have been described in this condition, and some authors have suggested that the two entities are associated. The purpose of this study was to determine the prevalence of vascular anomalies in Schimmelpenning syndrome.

Methods:

We reviewed the medical records of patients with Schimmelpenning syndrome who were evaluated or were managed at Children's Hospital Boston between 1980 and 2005. In addition, all published cases purported to be Schimmelpenning syndrome were analyzed to determine whether the primary diagnosis was accurate and whether or not there were concurrent vascular anomalies.

Results:

Three of nine patients (33.3%) in our series had a vascular malformation. One patient had coarctation, aortic aneurysm, renal artery, and carotid stenosis; another had a thoracic lymphatic anomaly with chylothorax; and the third had lymphedema of the lower extremities and lymphatic malformation of the neck/chest with chylothorax. Additional findings were seizures (78%), ocular pathology (78%), developmental delay (56%), and skeletal abnormalities (67%). Of 119 cases of authenticated Schimmelpenning syndrome in the literature, 18 vascular malformations were documented in 15 patients (12.6%): venous (n = 7); arterial (n = 5); lymphatic (n = 3); capillary (n = 2); and arteriovenous (n = 1).

Conclusions:

Vascular malformations occur with a higher frequency (12.6 to 33%) in patients with Schimmelpenning syndrome compared with the general population (<1%). Therefore, we conclude that there is an association between vascular anomalies and Schimmelpenning syndrome.

Nevus Sebaceous and Its Association With Neurologic Involvement

Several terms are widely used to define cutaneous lesions affecting the epidermis in association with extracutaneous lesions. Recently, based on the wide spectrum of cutaneous epidermal lesions, the various underlying molecular mechanisms and patterns of associated features have led to improved definitions of these disorders. Nevus sebaceous syndrome has been placed under the umbrella term of epidermal nevus syndrome, in which the nevus sebaceous, a congenital hamartomatous lesion of the epidermis, is associated with anomalies involving the brain, eyes, and bones. Nevus sebaceous and neurologic manifestations were evaluated particularly based on their degree of intellectual delay, seizure type, treatment response, and electroencephalography and neuroradiological findings. A review of the literature in this topic is reported.

A Rare Entity of Giant Epidermal Exophytic Naevus of Hemifacial Region

The term nevi constitute a hamartomatous growth of either skin or mucosa that is generally found at birth or shortly after birth. An epidermal nevus consisting chiefly of sebaceous glands is called as nevus sebaceous. Typically this entity is seen as a solitary bald patch over the scalp at birth. We report a case of exophytic lesion following blaschko's lines at birth. We find this case as peculiar because of the multiplicity of lesions, their pattern of distribution, as well as their atypical morphology.

A rare case of chylothorax in a patient with schimmelpenning syndrome

Chylothorax originating in a patient with Schimmelpenning syndrome is rare and poses a problem in diagnosis and treatment. A 22-year-old male was admitted with dyspnea indicative of a large pleural chylous effusion. Besides conservative dietary treatment measures, the chylous effusion was drained (2,000 mL/day). Computed tomography-lymphography after ligation of the thoracic duct and pleurectomy revealed a small collateral flow of chylous fluid toward the chest wall and entering the thorax. Eventually, local radiation therapy with 36 Gy effectively treated the chylothorax. Five months later, an epitheloid angiosarcoma developing from a preexisting cutaneous lesion was detected and treated by surgical resection.

Epidermal nevus syndromes

The term epidermal nevus syndrome (ENS) has been used to describe the association of epidermal hamartomas and extracutaneous abnormalities. Although many continue to use the term "ENS," it is now understood that this is not one disease, but rather a heterogeneous group with distinct genetic profiles defined by a common cutaneous phenotype: the presence of epidermal and adnexal hamartomas that are associated with other organ system involvement. One commonality is that epidermal nevi often follow the lines of Blaschko and it appears the more widespread the cutaneous manifestations, the greater the risk for extracutaneous manifestations. The majority of the extracutaneous manifestations involve the brain, eye, and skeletal systems. The CNS involvement is wide ranging and involves both clinical manifestations such as intellectual disability and seizures, as well as structural anomalies. Several subsets of ENS with characteristic features have been delineated including the nevus sebaceus syndrome, Proteus syndrome, CHILD syndrome, Becker's nevus syndrome, nevus comedonicus syndrome, and phakomatosis pigmentokeratotica. Advances in molecular biology have revealed that the manifestations of ENS are due to genomic mosaicism. It is likely that the varied clinical manifestations of ENS are due in great part to the functional effects of specific genetic defects. Optimal management of the patient with ENS involves an interdisciplinary approach given the potential for multisystem involvement. Of note, epidermal nevi have been associated with both benign and malignant neoplasms, and thus ongoing clinical follow-up is required.

Recent advances in pathophysiology studies and treatment of epilepsy in neurocutaneous disorders

Introduction.Epilepsy that is associated with neurocutaneous disorders seriously deteriorates quality of life and cognitive outcome of affected children. Recent advances in epilepsy pathophysiology raise hopes for better treatment results in this difficult group of patients.

Aim.The aim of this review is to present recent treatment recommendations as well as current research progress in the most frequent neurocutaneous disorders.

Material and methods.We analyzed PubMed database to select the most prominent and recent (up to 2014 year) publications on the treatment and mechanisms of epilepsy in selected neurocutaneous disorders. We aimed to emphasize evidence-based medicine recommendations as well as basic experimental studies dealing with molecular mechanisms of epileptogenesis.

Discussion and conclusions.Recent advances in disease-modifying treatment options such as mTOR inhibitors in patients with tuberous sclerosis complex open up new perspectives for neurologists. Traditional resective surgery has still a major role as a treatment of choice in carefully selected cases.

Becker's Nevus Syndrome

Becker's nevus is a cutaneous hamartoma characterized by circumscribed hyperpigmentation with hypertrichosis. Becker's nevus syndrome is an association of Becker's nevus with unilateral breast hypoplasia and muscle, skin, and/or skeletal abnormalities. We here report a case of a 15 year-old female who presented with bilateral Becker's nevus over her groins, thighs, vulva, and in front of the neck from the age of 5 years. She had associated mental retardation, delayed development of mile stones, delayed puberty, dwarfism, depressed nasal bridge, long slender digits, crowding of lateral toes, valgus deformity of first metatarsophalangeal joint, mitral valve prolapse, muddy conjunctiva with hypertrophic and hyperpigmented caruncle of both eyes, ichthyosis, brownish hair, and absence of axillary and pubic hair. On histopathological examination collagen hamartoma underneath the Becker's nevus was found.

Late onset epidermal nevus with hypertrichosis and facial hemihypertrophy

Epidermal nevus syndromes are rare conditions, characterized by different types of keratinocytic or organoid epidermal nevi in association with ocular, neurological, and skeletal manifestations. We present a case of late onset epidermal nevus with hypertrichosis and hemihypertrophy of face. Genetic analysis did not reveal presence of FGFR3 or PIK3CA mutations. The patient has features that cannot be categorized into the present well-known syndromes.

Therapeutic effects of CO2 laser therapy of linear nevus sebaceous in the course of the Schimmelpenning-Feuerstein-Mims syndrome

The Schimmelpenning-Feuerstein-Mims (SFM) syndrome is a rare phakomatosis which comprises a nevus sebaceous of Jadassohn, seizures and developmental delay associated with a wide spectrum of extracutaneous abnormalities including neurological, skeletal, ocular, cardiovascular and urogenital defects. We are presenting a case of an 18-year-old patient with systemic features of the SFM syndrome and an extensive linear nevus sebaceous partially removed with a carbon dioxide (CO2) laser. The treatment options of skin lesions in patients with SFM are discussed.

Somitic disruption of GNAS in chick embryos mimics progressive osseous heteroplasia

Progressive osseous heteroplasia (POH) is a rare developmental disorder of heterotopic ossification (HO) caused by heterozygous inactivating germline mutations in the paternal allele of the GNAS gene. Interestingly, POH lesions have a bewildering mosaic distribution. Using clinical, radiographic, and photographic documentation, we found that most of the 12 individuals studied had a lesional bias toward one side or the other, even showing exclusive sidedness. Most strikingly, all had a dermomyotomal distribution of HO lesions. We hypothesized that somatic mutations in a progenitor cell of somitic origin may act on a background of germline haploinsufficiency to cause loss of heterozygosity at the GNAS locus and lead to the unilateral distribution of POH lesions. Taking advantage of the chick system, we examined our hypothesis by mimicking loss of heterozygosity of GNAS expression using dominant-negative GNAS that was introduced into a subset of chick somites, the progenitors that give rise to dermis and muscle. We observed rapid ectopic cartilage and bone induction at the axial and lateral positions in a unilateral distribution corresponding to the injected somites, which suggests that blocking GNAS activity in a targeted population of progenitor cells can lead to mosaic ectopic ossification reminiscent of that seen in POH.

Angora hair nevus. A further case of an unusual epidermal nevus representing a hallmark of angora hair nevus syndrome

BACKGROUND

The association of Blaschko lines with genetic mosaicism has lead to the concept that this pattern represents the manifestation of genetically abnormal skin tissue contrasting with the genetically normal skin. Various mosaic defects affecting not only the skin but also extracutaneous tissues have lead to the description of different types of epidermal nevus syndromes. We present a further case of an unusual organoid epidermal nevus characterized by depigmented hypertrichosis.

MAIN OBSERVATIONS

We describe a 2-year-old boy with a systematized angora hair nevus being characterized by bands covered with soft white hair arranged along Blaschko's lines, involving the scalp, face, and trunk. A biopsy obtained from a scalp lesion showed mild epidermal acanthosis and increased pigmentation of the basal layer. Trichoscopy the affected scalp hair demonstrated fine light coloured shafts. The boy had slight macrocephaly and body asymmetry, a sacral pit, and koilonychia of the big toes.

CONCLUSIONS

The angora hair nevus is a peculiar type of organoid epidermal nevus, representing the cutaneous hallmark of a distinctive syndrome, the angora hair nevus syndrome (Schauder syndrome). In cases of epidermal nevi showing hypertrichosis, this unusual entity should be borne in mind for differential diagnosis.

Nevus sebaceus is a mosaic RASopathy

The recent discovery that nevus sebaceus is a mosaic RASopathy represents a major breakthrough in research on epidermal nevi. In this issue, both Levinsohn et al. and Sun et al. confirm this advancement with results obtained through whole-exome sequencing. Further molecular studies will almost certainly show that sebaceous and keratinocytic nevi are different disorders, although there is some clinical overlap.

Infantile inflammatory pseudotumor of the facial nerve as a complication of epidermal nevus syndrome with cholesteatoma

The first reported case of facial paralysis due to an inflammatory pseudotumor (IPT) of the facial nerve as a complication of epidermal nevus syndrome (ENS) is herein presented. A 10-month-old female patient was diagnosed with ENS at 3 months of age. She was referred to us because of moderate left facial paralysis. Epidermal nevi of her left auricle extended deep into the external ear canal. Otoscopy revealed polypous nevi and cholesteatoma debris filling the left ear. Computed tomography showed a soft mass filling the ear canal, including the middle ear, and an enormously enlarged facial nerve. Surgical exploration revealed numerous polypous nevi, external ear cholesteatoma, and tumorous swelling of the facial nerve. The middle ear ossicles were completely lost. The facial paralysis was improved after decompression surgery, but recurred 5 months later. A second operation was conducted 10 months after the first. During this operation, facial nerve decompression was completed from the geniculate ganglion to near the stylomastoid foramen. Histological diagnosis of the facial nerve tumor was IPT probably caused by chronic external ear inflammation induced by epidermal nevi. The facial paralysis gradually improved to House-Blackmann grade III 5 years after the second operation.

Epidermal nevus syndrome

Epidermal nevus syndrome (ENS) is an inclusive term for a heterogeneous group of congenital disorders characterized by the presence of epidermal nevi associated with systemic involvement. These disorders, as are all primary neurocutaneous syndromes, are neurocristopathies. The epidermal nevi that follow the lines of Blaschko and most systemic anomalies in skeletal, ocular, cardiovascular, endocrine, and orodental tissues, as well as lipomas, are due to defective neural crest. The most important and frequent anomaly in the brain in all forms of epidermal nevus syndromes (ENSs) is hemimegalencephaly (HME). This malformation often is not recognized, despite being the principal cause of neurological manifestations in ENSs. They consist mainly of epilepsy and developmental delay or intellectual disability. The onset of epilepsy in ENS usually is in early infancy, often as infantile spasms. Several syndromic forms have been delineated. I propose the term "Heide's syndrome" for those distinctive cases with the typical triad of hemifacial epidermal nevus, ipsilateral facial lipoma, and hemimegalencephaly. Most ENSs are sporadic. The mechanism is thought to be genetic mosaicism with a lethal autosomal dominant gene. Specific genetic mutations (PTEN, FGFR3, PIK3CA, and AKT1) have been documented in some patients. The large number of contributors for over more than a century and a half to the description of these disorders precludes the use of new author eponyms.

Hemimegalencephalic variant of epidermal nevus syndrome: case report and literature review

The epidermal nevus syndrome (ENS) is an uncommon neurocutaneous disorder in which epidermal nevi are found in association with congenital abnormalities of the brain, eye, and/or skeleton. The association of epidermal nevi and neurologic abnormalities was comprehensively described by Schimmelpenning in 1957. Pavone et al. (1991) identified a homogeneous variant of ENS with hemimegalencephaly, gyral malformation, mental retardation, seizures and facial hemihypertrophy. A 13-year-old boy with the neurologic variant of ENS with hemimegalencephaly, facial asymmetry, febrile seizures and mental retardation is reported. Additionally, we performed a literature review using the search terms "epidermal nevus syndrome" and "hemimegalencephaly", including secondary sources of data such as reference lists of articles reviewed. We found 57 previously reported cases with the hemimegalencephalic variant of epidermal nevus syndrome, in which the most frequent associated features are severe epilepsy, in about half of cases with neonatal onset, mental retardation/developmental delay, ocular/visual involvement, and facial abnormalities.

Multiple oncogenic mutations and clonal relationship in spatially distinct benign human epidermal tumors

Malignant tumors result from the accumulation of genetic alterations in oncogenes and tumor suppressor genes. Much less is known about the genetic changes in benign tumors. Seborrheic keratoses (SK) are very frequent benign human epidermal tumors without malignant potential. We performed a comprehensive mutational screen of genes in the FGFR3-RAS-MAPK and phosphoinositide 3-kinase (PI3K)-AKT pathways from 175 SK, including multiple lesions from each patient. SK commonly harbored multiple bona fide oncogenic mutations in FGFR3, PIK3CA, KRAS, HRAS, EGFR, and AKT1 oncogenes but not in tumor suppressor genes TSC1 and PTEN. Despite the occurrence of oncogenic mutations and the evidence for downstream ERK/MAPK and PI3K pathway signaling, we did not find induction of senescence or a DNA damage response. Array comparative genomic hybridization (aCGH) analysis revealed that SK are genetically stable. The pattern of oncogenic mutations and X chromosome inactivation departs significantly from randomness and indicates that spatially independent lesions from a given patient share a clonal relationship. Our findings show that multiple oncogenic mutations in the major signaling pathways involved in cancer are not sufficient to drive malignant tumor progression. Furthermore, our data provide clues on the origin and spread of oncogenic mutations in tissues, suggesting that apparently independent (multicentric) adult benign tumors may have a clonal origin.

Epidermal nevi

Nevi or nests of cells may be made up of a variety of cell types. The cell types that live in the epidermis include epidermal cells or keratinocytes, sebaceous glands, hair follicles, apocrine and eccrine glands, and smooth muscle cells. This article discusses epidermal or keratinocyte nevi, nevus sebaceous, nevus comedonicus, smooth muscle hamartomas, and inflammatory linear verrucous epidermal nevi. Syndromes associated with epidermal nevi are also reviewed.

The group of epidermal nevus syndromes Part I. Well defined phenotypes

The epidermal nevus syndromes represent a group of distinct disorders that can be distinguished by the type of associated epidermal nevus and by the criterion of presence or absence of heritability. Well defined syndromes characterized by organoid epidermal nevi include Schimmelpenning syndrome, phacomatosis pigmentokeratotica, nevus comedonicus syndrome, angora hair nevus syndrome, and Becker nevus syndrome. The molecular basis of these disorders has so far not been identified. By contrast, the group of syndromes characterized by keratinocytic nevi comprises three phenotypes with a known molecular etiology in the form of CHILD (congenital hemidysplasia with ichthyosiform nevus and limb defects) syndrome, type 2 segmental Cowden disease, and fibroblast growth factor receptor 3 epidermal nevus syndrome (García-Hafner-Happle syndrome), whereas Proteus syndrome is still of unknown origin. From this overview, it is clear that a specific type of these disorders cannot be classified by the name "epidermal nevus syndrome" nor by the terms "organoid nevus syndrome" or "keratinocytic nevus syndrome."

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to distinguish nine different epidermal nevus syndromes by their characteristic features, understand the practical significance of avoiding terms like "epidermal nevus syndrome" or "keratinocytic nevus syndrome" to define any specific entity within this group of disorders, and differentiate between nonhereditary traits and those bearing a genetic risk because of either Mendelian or non-Mendelian inheritance.

Oral linear epidermal nevus: a review of the literature and report of two new cases

Linear epidermal nevus (LEN) is a sporadic hamartomatous lesion of the skin due to the proliferation of clones of embryonic ectodermal cells, which are arranged according to a typical linear configuration known as Blaschko's lines. Oral involvement of LEN is very rare and few cases have been reported in the medical literature. We report two new cases of LEN with exclusive oral involvement, which presented with the typical unilateral or midline distribution. Oral LEN presents as an exophytic lesion with well defined borders and a verrucous or papillary surface which correspond, histologically, to epithelial papillomatosis with a moderate degree of hyperkeratosis and acanthosis. Oral LEN appears mainly at birth, grows slowly during childhood and stabilize by adolescence. Localized lesions do not show any recurrence after surgical removal but widespread lesions seem to have more risk of recurrence and are more difficult to manage. Functional problems and malignant transformation have not been reported.

Nevus marginatus: a distinct type of epidermal nevus or merely a variant of nevus sebaceus?

Epidermal nevi (EN) represent a heterogeneous group of mosaic skin lesions frequently following the lines of Blaschko. They are divided into organoid and nonorganoid types. Herein we report on a 35-year-old man with a rather unusual type of EN. A linear lesion involving the trunk and following Blaschko's lines was conspicuously bordered by dark brown papules. The flat reddish central area histopathologically showed sebaceous hyperplasia consistent with nevus sebaceus, an organoid EN type, whereas the elevated margin showed features of a common nonorganoid keratinocytic EN. For this peculiar disorder, we propose the term 'nevus marginatus'. So far it is not clear whether nevus marginatus represents a distinct entity or merely an unusual clinical variant of nevus sebaceus.

Giant bilateral becker nevus: a rare presentation

A 14-year-old boy had giant confluent brown patches that were bilaterally distributed on his back, chest, and upper arms, and partially covered by dark coarse hairs. A clinical diagnosis of Becker nevus was made and confirmed histopathologically. We report this patient for the rarity of presentation. Different clinical features of Becker nevi, associated findings, differential diagnoses, and treatment options are discussed.

Phacomatosis pigmentokeratotica associated with a suprasellar dermoid cyst and leg hypertrophy

Phacomatosis pigmentokeratotica (PP) is a mosaic disorder that represents a distinct epidermal naevus syndrome. Its defining features are an epidermal naevus that is usually of the sebaceous type and a speckled lentiginous naevus arranged in a chequerboard pattern. In addition, there are neurological, ophthalmological and skeletal abnormalities, including limb hemiatrophy with muscular weakness, ptosis, seizures and ipsilateral segmental hyperaesthesia and hyperhidrosis. We report a 44-year-old man with an extensive epidermal naevus and an ipsilateral speckled lentiginous naevus. He also had ipsilateral right leg hypertrophy and a suprasellar dermoid cyst with associated neurological abnormalities. We propose that this case represents an unusual example of PP.

Epidermal nevus syndrome and didymosis aplasticosebacea

The epidermal nevus syndrome is a disease complex consisting of the association of an epidermal nevus with various developmental abnormalities of the skin, eyes, nervous, skeletal, cardiovascular, and urogenital systems. The epidermal nevi are classified according to their predominant component; nevus sebaceus (sebaceous glands), nevus comedonicus (hair follicles), and nevus verrucosus (keratinocytes). We report a neonate who presented with a nevus sebaceus on the scalp and face as well as a coloboma and dermoid on his left eye. Within the sebaceous nevus on the scalp, circumscribed lesions of aplasia cutis congenita were detected, which is consistent with the recently proposed term in the literature didymosis aplasticosebacea.

Epidermal nevus syndrome

Epidermal nevus syndrome is a group of congenital neurocutaneous disorders characterized by epidermal nevi in association with cerebral, ocular, skeletal, and sometimes cardiac and renal abnormalities. These nevi have been classified according to their predominant component. We described a child presenting with inflammatory linear verrucous epidermal nevus on the head, which is an uncommon location. He also encountered ocular and central nervous system structural disorders.

Nevus sebaceous syndrome with facial hemihypertrophy

Nevus sebaceous syndrome is a member of the epidermal nevus syndromes group, and is characterized by extensive nevus sebaceous, seizures, and mental retardation. We present an affected 5-month-old boy who had facial hemi-hypertrophy and recurrent seizures.

Widespread porokeratotic eccrine ostial and dermal duct nevus along Blaschko lines

Porokeratotic eccrine ostial and dermal duct nevus is a congenital hamartoma of possible eccrine origin with no malignant potential. It is usually localized at the extremity of a single limb, while wider systematized distribution has rarely been documented. A child with an unusually widespread nevus following Blaschko lines is reported. The disorder had a striking presentation in the form of a systematized linear epidermal nevus composed of multiple tiny filiform keratotic spines, which histologically corresponded to columns of porokeratosis. Serial histopathologic sections of a 4-mm punch biopsy specimen barely demonstrated an anatomic relationship between the porokeratotic columns and the underlying acrosyringeal duct. This report provides further evidence of porokeratotic eccrine ostial and dermal duct nevus being distributed along Blaschko lines, thus confirming it is a peculiar epidermal nevus due to a mosaic cutaneous condition.

Distinct mechanisms underlie pattern formation in the skin and skin appendages

Patterns form with the break of homogeneity and lead to the emergence of new structure or arrangement. There are different physiological and pathological mechanisms that lead to the formation of patterns. Here, we first introduce the basics of pattern formation and their possible biological basis. We then discuss different categories of skin patterns and their potential underlying molecular mechanisms. Some patterns, such as the lines of Blaschko and Naevus, are based on cell lineage and genetic mosaicism. Other patterns, such as regionally specific skin appendages, can be set by distinct combinatorial molecular codes, which in turn may be set by morphogenetic gradients. There are also some patterns, such as the arrangement of hair follicles (hair whorls) and fingerprints, which involve genetics as well as stochastic epigenetic events based on physiochemical principles. Many appendage primordia are laid out in developmental waves. In the adult, some patterns, such as those involving cycling hair follicles, may appear as traveling waves in mice. Since skin appendages can renew themselves in regeneration, their size and shape can still change in the adult via regulation by hormones and the environment. Some lesion patterns are based on pathological changes involving the above processes and can be used as diagnostic criteria in medicine. Understanding the different mechanisms that lead to patterns in the skin will help us appreciate their full significance in morphogenesis and medical research. Much remains to be learned about complex pattern formation, if we are to bridge the gap between molecular biology and organism phenotypes.

Skeletal changes in epidermal nevus syndrome: does focal bone disease harbor clues concerning pathogenesis?

Epidermal nevus syndrome (ENS) is a rare, sporadic, congenital disorder of unknown etiology featuring a complex and highly variable phenotype that can include focal or generalized skeletal disease. We describe a young man with ENS manifesting right-sided linear skin lesions, generalized weakness, diffuse osteopenia associated with hypophosphatemic rickets, and distinctive focal bone lesions ipsilateral to the skin findings. Review of the literature concerning ENS-associated skeletal disease suggested such focal bone defects are fibrous dysplasia, but our patient did not have the typical radiographic or histopathologic findings of fibrous dysplasia. Nevertheless, his circulating fibroblast growth factor 23 (FGF-23) level was elevated, likely functioning as a "phosphatonin," yet no activating mutations in GNAS previously reported in fibrous dysplasia or McCune-Albright syndrome were detected in his leukocytes or affected skin. We postulate that the focal skeletal disease, although different than fibrous dysplasia, may be a source of FGF-23 in ENS.

Nevo de Becker asociado a nevo epidérmico: ¿un ejemplo más de «manchas gemelas»?

Linear epidermal nevi are believed to be caused by an autosomal dominant lethal mutation that can only be expressed by mosaicism. Becker's nevus can be explained by paradominant inheritance which is only manifested clinically by an acquired loss of heterozygosity. We present the case of a 16-year-old female with an epidermal nevus located on the left side of the neck, and also a Becker's nevus located on the ipsilateral shoulder. It is interesting to speculate that this supposed double mosaicism could be another example of "twin spotting" or non-allelic didymosis, although the possibility that this is a chance association cannot be ruled out, as the lesions are not closely associated.

Intraoral lesions associated with sebaceous nevus syndrome

The sebaceous nevus syndrome describes the rare association of a sebaceous nevus with systemic features such as mental retardation, seizures and colobomas (among others). It is thought to be a cutaneous mosaic inherited as a paradominant trait. Three cases are provided illustrating the intraoral manifestations of the syndrome. The first histological comparison of contiguous mucosal and cutaneous lesions is provided. We also describe the possible association of SFM syndrome with a benign fibrous histiocytic lesion of the mandible. This and other mandibular tumors associated with the sebaceous nevus syndrome may have significant implications for patients. Awareness of the potential presence or development of significant intraoral lesions in association with the sebaceous nevus syndrome is important for those involved in the care of patients with this syndrome.

[The skin as an expression of neurological alterations in the neonate]

The skin is involved in many different genetic syndromes and diseases with multiple organ involvement. Neurodevelopmental disorders appear in many of these entities and knowledge of these cutaneous alterations may provide clues to their diagnosis. Recognizing these skin disorders in the newborn allows early identification of neonates with a biological risk of epilepsy and motor and/or cognitive disorders and enables them to be followed up. This helps to plan the management of these patients and, in many entities, to predict their natural history and provide genetic counseling to the family. This review examines the cutaneous signs that may provide important clues in the neonate that help to identify entities that carry a risk of neurodevelopmental disorders in the neonate.

Epidermal nevus syndrome associated with adnexal tumors, spitz nevus, and hypophosphatemic vitamin D-resistant rickets

The epidermal nevus syndrome is the association of epidermal nevi with abnormalities in other organ systems, most commonly the central nervous system, the skeletal system, and the eyes. We present a patient with epidermal nevus syndrome associated with hypophosphatemic vitamin D-resistant rickets and multiple adnexal and spindle cell tumors.

Epidermal nevus syndromes

The term "epidermal nevus syndrome" (ENS) has been used to describe the association of epidermal hamartomas and extra-cutaneous abnormalities. Epidermal nevi follow the lines of Blaschko. The majority of the extra-cutaneous manifestations involve the brain, eye, and skeletal systems. Several subsets with characteristic features have been delineated including the nevus sebaceous syndrome, Proteus syndrome, CHILD syndrome, Becker nevus syndrome, nevus comedonicus syndrome, and phakomatosis pigmentokeratotica. Epidermal nevi have been associated with benign and malignant neoplasms. Advances in molecular biology have revealed that the manifestations of ENS are due to genomic mosaicism. It is likely that the varied clinical manifestations of ENS are due in great part to the functional effects of specific genetic defects. Optimal management of the patient with ENS involves an interdisciplinary approach. Amelioration of the cutaneous features of ENS has been difficult but there have been advances, especially in the use of lasers.