Objective. To determine the risk for developing malignant melanoma and neurocutaneous melanocytosis (NCM) in patients with large congenital melanocytic nevi. Design. Follow-up data suitable for calculations were available on 160 patients in the New York University Registry of Large Congenital Melanocytic Nevi who had been free of known melanomas or NCM when entered into the Registry. The cumulative 5-year life-table risks for developing melanoma and NCM were calculated. The relative risk for developing melanoma, using a control general population reference group, was determined. Results. The 160 patients (median age at entry: 14 months) were followed prospectively for an average of 5.5 years. Three extracutaneous melanomas developed: 2 were in the central nervous system (CNS) and 1 was retroperitoneal. The 5-year cumulative life-table risk for developing melanoma was 2.3% (95% confidence interval [CI]: .8–6.6) and the relative risk was 101 (95% CI: 21–296). No melanoma occurred within a large congenital melanocytic nevus. Four patients developed manifest NCM, 2 with CNS melanomas. The 5-year cumulative life-table risk for developing NCM was 2.5% (95% CI: .8–7.2). Ten patients were excluded from the calculations because of preexisting disease on entry into the Registry: 5 with manifest NCM and 5 with melanomas (3 in large congenital melanocytic nevi, 1 in nonnevus skin, and 1 unknown primary). Conclusions. Patients with large congenital melanocytic nevi are at increased risk for developing melanomas. There is also a significant increased risk for developing NCM. The high incidence of CNS involvement may influence decisions concerning treatment of the large congenital melanocytic nevi.

Large congenital melanocytic nevi and the risk for development of malignant melanoma and neurocutaneous melanocytosis.

https://www.jidonline.org/article/S0022-202X(15)36385-5/pdf

Multiple Congenital Melanocytic Nevi and Neurocutaneous Melanosis Are Caused by Postzygotic Mutations in Codon 61 of NRAS

The medical care of patients affected by rare disorders depends heavily on experiences garnered from prior cases, including those patients evaluated by the treating physician and those published in the medical literature. The utility of published cases is wholly dependent upon accurate diagnosis of those patients. In our experience, the rate of misdiagnosis in Proteus syndrome (PS) is high. Diagnostic criteria have been published, but these criteria have not been applied consistently and were published after many case reports appeared in the literature. We reviewed 205 cases of individuals reported to have PS in the literature and three of us independently applied the diagnostic criteria to these case reports. Our initial diagnostic congruence was 97.1% (199/205); the discrepancies in six cases were easily resolved. Only 97 (47.3%) of reported cases met the diagnostic criteria for PS; 80 cases (39%) clearly did not meet the criteria; and although 28 cases (13.7%) had features suggestive of PS, there were insufficient clinical data to make a diagnosis. Reported cases that met the PS criteria had a higher incidence of premature death, and other complications (scoliosis, megaspondyly, central nervous system abnormalities, tumors, otolaryngologic complications, pulmonary cystic malformations, dental and ophthalmogic complications) compared to those in the non-Proteus group. The cases that met the criteria were more often male, which has implications for hypotheses regarding the etiology and pathophysiology of PS. We also studied the attributes that led authors to conclude the reported patients had PS when we concluded they did not. We found that two of the diagnostic criteria (disproportionate overgrowth and connective tissue nevi) were often misinterpreted. In PS, the abnormal growth is asymmetric, distorting, relentless, and occurred at a faster rate compared to the rest of the body. Furthermore, PS was associated with irregular and disorganized bone, including hyperostoses, hyperproliferation of osteoid with variable calcification, calcified connective tissue, and elongation of long bones with abnormal thinning. In contrast, non-Proteus cases displayed overgrowth that was asymmetric but grew at a rate similar to the growth found in unaffected areas of the body. Also, the overgrowth in non-Proteus cases was associated with normal or enlarged bones together with ballooning of the overlying soft tissues. Taken together, these data show that (1) PS diagnostic criteria sort individuals with asymmetric overgrowth into distinct groups; (2) individuals with PS were more likely to have serious complications; (3) PS affects more males than females; and 4) the published diagnostic criteria are useful for clinical care and research. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299/suppmat/index.html.

https://zenodo.org/record/1229111/files/article.pdf

Reassessment of the Proteus syndrome literature: application of diagnostic criteria to published cases.

Congenital melanocytic nevi (CMN) can be associated with neurological abnormalities and an increased risk of melanoma. Mutations in NRAS, BRAF, and Tp53 have been described in individual CMN samples; however, their role in the pathogenesis of multiple CMN within the same subject and development of associated features has not been clear. We hypothesized that a single postzygotic mutation in NRAS could be responsible for multiple CMN in the same individual, as well as for melanocytic and nonmelanocytic central nervous system (CNS) lesions. From 15 patients, 55 samples with multiple CMN were sequenced after site-directed mutagenesis and enzymatic digestion of the wild-type allele. Oncogenic missense mutations in codon 61 of NRAS were found in affected neurological and cutaneous tissues of 12 out of 15 patients, but were absent from unaffected tissues and blood, consistent with NRAS mutation mosaicism. In 10 patients, the mutation was consistently c.181C>A, p.Q61K, and in 2 patients c.182A>G, p.Q61R. All 11 non-melanocytic and melanocytic CNS samples from 5 patients were mutation positive, despite NRAS rarely being reported as mutated in CNS tumors. Loss of heterozygosity was associated with the onset of melanoma in two cases, implying a multistep progression to malignancy. These results suggest that single postzygotic NRAS mutations are responsible for multiple CMN and associated neurological lesions in the majority of cases.

Multiple Congenital Melanocytic Nevi and Neurocutaneous Melanosis Are Caused by Postzygotic Mutations in Codon 61 of NRAS (vol 133, pg 2229, 2013)

Naevi and Other Developmental Defects

Background Silvery hair and severe dysfunction of the central nervous system (neuroectodermal melanolysosomal disease or Elejalde syndrome) characterize this rare autosomal recessive disease. Main clinical features include silver-leaden hair, bronze skin after sun exposure, and neurologic involvement (seizures, severe hypotonia, and mental retardation). Large granules of melanin unevenly distributed in the hair shaft are observed. Abnormal melanocytes and melanosomes and abnormal inclusion bodies in fibroblasts may be present. Differential diagnosis with Chediak-Higashi syndrome and Griscelli syndrome must be done. Observations We studied pediatric patients with silvery hair and profound neurologic dysfunction. Immune impairment was absent. Age of onset of neurologic signs ranged from 1 month to 11 years; the signs included severe muscular hypotonia, ocular alterations, and seizures. Mental retardation since the first months of life was noted in 4 cases. Psychomotor development was normal in 3 cases, but suddenly the patients presented with a regressive neurologic process. Four patients died between 6 months and 3 years after the onset of neurologic dysfunction. One patient showed characteristic ultrastructural findings of Elejalde syndrome. Conclusions Elejalde syndrome is different from Chediak-Higashi and Griscelli syndrome and is characterized by silvery hair and frequent occurrence of fatal neurologic alterations. Psychomotor impairment may have 2 forms of presentation: congenital or infantile. Although Elejalde syndrome and Griscelli syndrome are similar, the possibility that they are 2 different diseases, although probably allelic related, is suggested.

https://jamanetwork.com/journals/jamadermatology/articlepdf/477721/dob8029.pdf

Elejalde syndrome--a melanolysosomal neurocutaneous syndrome: clinical and morphological findings in 7 patients.

Background: Magnetic resonance imaging (MRI) findings suggestive of neurocutaneous melanosis (NCM) have been reported in asymptomatic patients with giant congenital melanocytic nevi

Giant congenital melanocytic nevi, neurocutaneous melanosis and neurological alterations.

Three cutaneous manifestations are characteristic of Bart syndrome: congenital localized absence of skin (CLAS), mucocutaneous blistering, and nail abnormalities. Six cases of Bart syndrome are herein reported. Localized absence of skin is present at birth, particularly on the anterior aspects of the lower extremities and dorsa of the feet. Physical trauma in utero has been proposed as a mechanism to explain the denuded areas on the limbs. The recurrent, highly similar pattern of the congenital defect in regard to location and clinical appearance in our patients and in most of the reported cases strongly suggests that trauma is too simplistic an explanation. Because of the observed bilateral and symmetric distribution of denuded areas in an S-shaped broad band, their sharply demarcated borders, the involvement of the toe webs, and the frequent similar involvement of the soles, we suggest that congenital localized absence of skin in Bart syndrome may follow the lines of Blaschko.

Bart Syndrome: The Congenital Localized Absence of Skin May Follow the Lines of Blaschko. Report of Six Cases

Seven children with Proteus syndrome (PS) are reported. The majority of clinical findings coincide with what is reported in the literature. New findings were blue sclerae, telecanthus, epiblepharon, endotropy, hemimegaly of the optic nerve, occipital dysmyelination and compression of the corpus callosum, craneosynostosis, decalcification and thinning of the cortical layer of long bones, and talipes equinus. The clinical findings, possible etiology, differential diagnosis, and treatment of PS are discussed.

M de la Luz Orozco-Covarrubias

Papers

Elejalde syndrome--a melanolysosomal neurocutaneous syndrome: clinical and morphological findings in 7 patients.

Giant congenital melanocytic nevi, neurocutaneous melanosis and neurological alterations.

Bart Syndrome: The Congenital Localized Absence of Skin May Follow the Lines of Blaschko. Report of Six Cases

Proteus syndrome: new findings in seven patients