Lichen planus limited to the nails in childhood: case report and literature review

Trachyonychia and Twenty-Nail Dystrophy: A Comprehensive Review and Discussion of Diagnostic Accuracy

BACKGROUND/AIMS

The term trachyonychia, also known as twenty-nail dystrophy, is used to describe thin, brittle nails with excessive longitudinal ridging. The term twenty-nail dystrophy has been incorrectly applied to other conditions that can affect all twenty nails. Therefore, we have conducted a comprehensive review of the clinical features of trachyonychia and have included a discussion regarding the diagnostic accuracy of this condition in the literature.

METHODS

In November and December 2015, we conducted a thorough literature search using the following search terms: 'trachyonychia', 'twenty nail dystrophy', and 'sandpaper nails'. Articles that reported the epidemiology, disease associations, clinical presentation, histopathology, and treatment options for trachyonychia were included. Particular attention was given to case reports to identify misdiagnosed cases of twenty-nail dystrophy.

RESULTS

Our preliminary search yielded 184 results with 72 unique articles ultimately selected for review. Excluded articles included 27 articles in languages other than English, 18 commentaries or reviews, and 67 irrelevant articles. Twelve additional articles described nail abnormalities clinically different from trachyonychia.

CONCLUSION

Many other conditions can cause widespread nail dystrophy. The specific characteristics of trachyonychia need to be considered to make the diagnosis of twenty-nail dystrophy.

Nail disorders in children: diagnosis and management

Nail disorders in children can be divided into seven categories. The first is physiologic alterations, which every physician should be aware of in order to reassure parents. These usually disappear with age and do not require any treatment. Among congenital and inherited conditions, the nail-patella syndrome, with its pathognomonic triangular lunula, should not be missed as recognition of the disease allows early diagnosis of associated pathologies. The most common infection is the periungual wart, whose treatment is delicate. Herpetic whitlow should be distinguished from bacterial whitlow as their therapeutic approaches differ. Dermatologic diseases encompass eczema, psoriasis, lichen planus, lichen striatus, trachyonychia, and parakeratosis pustulosa. Lichen planus, when it presents as in adults, is important to recognize because, if not treated, it may lead to permanent nail loss. Systemic or iatrogenic nail alterations may be severe but are usually not the first clue to the diagnosis. Beau lines on several fingernails are very common in children after temperature crest. Tumors are rare in children. Radiographic examination allows confirmation of the diagnosis of subungual exostosis. Other cases should undergo biopsy. Single-digit longitudinal melanonychia in children is mostly due to nevi. Its management should be tailored on a case-by-case basis. Acute trauma should never be underestimated in children and hand surgeons should be involved if necessary. Onychophagia and onychotillomania are responsible for chronic trauma.

Lichen planus in African children: a study of 13 patients

Lichen planus is an uncommonly encountered dermatosis in children, reported worldwide, however in sub-Saharan Africa there is paucity of data on Lichen planus among children. The aim of this study was to document the clinical types of Lichen planus observed in children in South East Nigeria from 1998 to 2001; and to highlight any differences and similarities with adult disease. In all, 13 patients (eight boys and five girls) aged between 3 and 15 years were diagnosed with Lichen planus. The limbs were the most common sites of involvement for nine (69.2%) children. Classic Lichen planus was the commonest clinical variant in eight (61.5%), while extensive hypertrophic plaques were observed in three (23.1%), linear lesions in two (15.4%) and eruptive generalized Lichen planus in two (15.4%). Koebner phenomenon was documented in five (38.5%); mucosal involvement, which is very uncommon in children affected by this disease, occurred in three (23.1%). Only one child had pterygium formation in all 20 nails (total nail dystrophy). No child had scalp or palmoplantar involvement. Despite the endemicity of hepatitis B surface antigen in our environment, this study also revealed that liver function tests were not significantly different between children with Lichen planus and hepatitis B surface antigen and those who were negative for this antigen; while anti-hepatitis C virus seropositivity was not recorded in any of these children.

FOXN1 is critical for onycholemmal terminal differentiation in nude (Foxn1) mice

Nude mice have a mutation in the transcription factor Foxn1(nu), resulting in downregulation of hair keratins. Although hair follicles develop normally, the hair fibers become structurally weak, curl, and break off at the surface. Nails in nude mice are deformed, based on alterations of the onychocyte differentiation process. Elemental microanalysis of the nail plate reveals marked decreases in sulfur concentrations in the nude mouse nail plates. Immunohistochemistry shows a lack of keratin 1 expression in terminally differentiating keratinocytes of the nail matrix. Instead, the typical differentiation process of the matrix is altered toward an epidermis-like differentiation pattern, comprising the production of filaggrin-containing keratohyalin granules in cells resembling those of the stratum granulosum, which are never observed in normally haired mice. The nail plate has diffuse basophilic stippling. It is thinner than normal, weak, and in most Foxn1(nu)/Foxn1(nu) mice breaks where it separates from the hyponychium. These studies indicate that the Foxn1(nu) mutated gene has effects beyond downregulating keratin expression, including changes in filaggrin expression, and is critical for normal onycholemmal differentiation. The nails of nude mice provide new insights into the molecular controls of onychocyte differentiation, and they offer a useful model to investigate the pathogenesis of nail hypergranulosis, a common feature in human nail diseases.

Twenty-nail dystrophy in a girl with incontinentia pigmenti

A 9-year-old girl with incontinentia pigmenti (IP) diagnosed soon after birth subsequently developed 20-nail dystrophy at the age of 3 years. This persists unchanged 6 years later, and she has no other evidence of any other cutaneous disease, nor a family history of IP or nail dystrophy. Twenty-nail dystrophy has been associated with a number of diseases including eczema, lichen planus, alopecia areata and psoriasis and a number of other congenital associations, but the association with IP appears to be unique.

Lichen planus in the lines of Blaschko

We describe three adolescents with eruptive linear lesions of the back, abdomen, and extremities distributed along the lines of Blaschko. Clinically one of these lesions resembled an epidermal nevus in its morphology and distribution. A biopsy specimen demonstrated the typical histology of lichen planus (LP). There have been fewer than 20 reported cases of childhood linear LP. Our patients demonstrate that linear LP sometimes may closely resemble an epidermal nevus and may auger the onset of more generalized LP or more involvement along the lines of Blaschko, that is, "Blaschkoian" disease. Previous studies have referred to this variant as zosteriform. Our cases are the fourth, fifth, and sixth cases of childhood LP reported to occur along the lines of Blaschko. Based on the clinical findings in our patients and a review of the English-language literature, we believe that linear LP is usually distributed along the lines of Blaschko and should be renamed lichen planus, Blaschko subtype.

Childhood lichen planus: a study of 87 cases

AIMS

We undertook this study to analyze the clinical profile of childhood lichen planus (LP) prevailing in north India, and to highlight differences from and similarities with adult LP.

METHODS

Clinical records of children with LP, who attended the Pediatric Dermatology Clinic, Nehru Hospital, Postgraduate Institute of Medical Education and Research, Chandigarh, India, from July 1988 to December 2000, were analyzed.

RESULTS

Eighty-seven patients with LP were examined during a 12.5-year period of observation. These patients formed 2.5% of the total number of pediatric dermatology patients and 0.6% of the total number of new dermatology outpatients. The male : female ratio was 1.1 : 1. The age at onset was between 8 months and 12 years (mean, 7.1 years). Classical LP was observed in 53 (60.9%) patients, followed by actinic LP in 10 (11.5%), and lichen planus hypertrophicus (LPH) and linear LP in eight (9.2%) each. Other forms seen were eruptive, follicular, lichen planopilaris, atrophic, and bullous LP. The involvement of skin alone was observed in 75 (86.2%) children and mucosa alone only in one (1.1%) child. Concomitant skin and mucosal involvement was seen at the time of presentation in four patients, while mucosal involvement occurred later during the course of the disease in seven patients. Lesions appeared earlier in boys than in girls.

CONCLUSIONS

The natural history of LP in children was essentially similar to that in adults. Unusual features, such as involvement of the palms and soles and upper eyelids, were observed. Actinic LP, mimicking melasma, as reported in adult women, also seems to occur in children.

Assignment of the gene for a new hereditary nail disorder, isolated congenital nail dysplasia, to chromosome 17p13

Isolated congenital nail dysplasia is an autosomal dominant disorder recently observed in a large family from southern Germany. The disorder is characterized by longitudinal streaks, thinning, and impaired formation of the nail plates leading to increased vulnerability of the free nail margins. In most cases, all fingernails and toenails are similarly involved with some accentuation of the thumb and great toenails. Histologic changes include hypergranulosis of the nail matrix and epithelial outgrowths from the nail bed. Patients do not show any alterations of hair growth and dentition, no malfunction of sweat glands and sensory organs, and no skeletal abnormalities. Isolated congenital nail dysplasia manifests from the first year of life with variable expressivity. In order to localize chromosomally the gene underlying isolated congenital nail dysplasia, linkage to the known keratin gene cluster regions on chromosomes 12q12 and 17q21 was ruled out first. The analysis of 150 microsatellite markers on various chromosomes mapped the isolated congenital nail dysplasia gene to the 6 cM interval between markers at D17S926 and D17S1528 on chromosome 17p13. Markers at D17S849, D17S 1840, and D17S1529 co-segregated completely with the isolated congenital nail dysplasia locus. The maximum two-point LOD score was found for the marker at D17S 1840 (Zmax = 6.72 at Thetamax = 0.00). The identified region harbors no currently known genes involved in skin or nail abnormalities. Isolated congenital nail dysplasia probably represents a novel isolated defect of nail development. The localization of this gene is, therefore, the first step towards the identification of a new factor in nail formation.

Adult skin disease in the pediatric patient

The incidence of many skin diseases peak in adulthood, and these disorders may be difficult to recognize when they do present in childhood. Their clinical features may be distinct in pediatric patients, and they may be managed differently in children as compared to adults. Therefore, it is important that dermatologists are able to identify "adult" skin disease in the pediatric patient, and know how to appropriately manage these problems in young patients. The epidemiology, clinical features, differential diagnosis, and management of the following "adult" skin diseases in children are reviewed: psoriasis, lichen planus, rosacea, Sweet's syndrome, and mucosis fungoides. Distinctive features of lichen sclerosus and immunobullous diseases in childhood will also be briefly discussed.