Introduction
Nail disorders in infants and children are relatively uncommon. Their incidence is influenced by ethnic, environmental, and socioeconomic factors and varies in different populations and studies. Only a few papers have described the frequency of nail alterations in the pediatric population. Iglesias et al.[1] reported the prevalence of nail disorders as 11% in children under 17 years of age in their study. Few studies in Turkey have found the incidence of pediatric nail disorders varying between 0.7% and 4.4%.[2] Their presentation and management are different from adults. Physiological alterations are common in pediatric age and should be known to a clinician to differentiate from pathological conditions. The congenital nail disorders can be a part of major hereditary syndromes, requiring further evaluation. Several acquired causes may cause variable dystrophy of the nails. Meticulous and careful nail examination is, therefore, important in neonates, infants and children for early diagnoses, management and to prevent complications. There are no large epidemiological studies delineating nail changes in infants and children.
Nail disorders in children can be grouped as in [Box 1].
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Box 1: Nail disorders in children
Embryology And Anatomy
Formation of nail apparatus begins in 8th week of gestation and is accomplished by 5th month of intrauterine life.[3] Nails in newborns are thin and soft. The growth of nail is maximum between 10–12 years of age and its length and breadth increases in first two decades of life.[4] At birth, nail plate generally reaches up to the tip of margins, indicating fetal maturity [Figure 1b].[5] Nails in postmature infants usually extend beyond the hyponychium [Figure 1c]. Similarly, the nail plate of premature infants is shorter than the distal nail pulp [Figure 1a]. Figure 2 illustrates the basic anatomy of the nail unit.
Figure 1: Nails in neonates at preterm (a), term (b) and post term (c)
Figure 2: Nail unit in a child and its components
Physiological Alterations
Physiological nail alterations are common in children. They usually disappear with age and do not require any treatment. Knowledge of these changes is important to reassure parents.
Fingernails in newborns are generally oval in shape or have a flat curvature.[6] Absence of lunula is seen in 50% of newborns.[6] Toenails are triangular or round. The thin and triangular nail plate induces a force that pushes the lateral folds down resulting in overlapping. Due to this, 73% of newborns have an apparent or pseudohypertrophy of proximal and lateral nail fold, mimicking a pseudo-ingrown nail.[6] The common physiological nail changes in children according to their age are listed in Table 1.[47]
Table 1: Physiological nail changes
Koilonychia
It is characterized by flat or concave nail surface. It is present in the great toe of 33% of infants. Nail plate curvature is reversed in both transverse and longitudinal axis leading to spooning.[8] It tends to disappear spontaneously in first 10 years of life as the nail plate thickens.[6910]
Onychoschizia and onycholysis
Onychoschizia is transverse and lamellar splitting of the distal portion of the nail plate, most commonly caused by trauma.[8] Thumb sucking is an important exacerbating factor.[9] Onychoschizia and onycholysis of the toenails and thumbs are a transient physiological alteration seen in 29% and 27% of newborns, requiring no treatment.[46]
Leukonychia
Leukonychia can be true (nail matrix pathology), apparent (nail bed pathology), or pseudo (exogenous). It may involve entire nail or partial; latter may be punctate [Figure 3], transverse or longitudinal. Punctate leukonychia is frequently seen in newborns and toddlers as a consequence of minimal trauma to proximal nail matrix at birth.[411] Transverse leukonychia is rare in children and is restricted to great toes due to trauma to the distal matrix from shoes.[4]
Figure 3: Punctate leukonychia in the fingernails of 8-year-old girl
Beau's lines
Beau's lines are seen in fingernails of 92% newborns with the occasional presence of onychomadesis.[9] They result from intrauterine distress. They appear at 4 weeks of life and tend to grow out before 14 weeks.[4]
Nail pitting
Nail pits result from defective keratinization of proximal matrix. They may be physiological in children and toddlers.
Periungual pigmentation
A regular reticular pattern of transient light-brown or ochre color pigmentation in the periungual area, proximal nail fold (PNF), and dorsal digit till interphalangeal joint is a physiological pigmentation appearing in infants in the first 6 months of life.[4]
Chevron nails
The nail plate in chevron or herringbone nails shows oblique and longitudinal diagonal ridges converging toward the center of the distal part of the nail plate. They appear between 5 and 7 years of age and disappear in early adulthood.[4] They are of unknown significance but may be concerned with dynamics and pattern of nail growth.[10]
Clubbing
It is characterized by increased transverse and longitudinal curvature with soft-tissue hypertrophy of distal digital. It can be idiopathic, hereditary–congenital or acquired. Physiological clubbing may be seen in newborns when the nail curves over the tip of the digit.[4]
Nail biting/onychophagia
Onychophagia usually starts in early childhood after 3–4 years of age,[12] with a reported prevalence of 20%–33% in 7–10 years old children.[13] It can lead to irreversibly shortened nails, paronychia, ragged cuticle, and hangnails [Figure 4].
Figure 4: Onychophagia with ragged cuticle and hangnails
Other changes
A small degree of deviation of great hallux from the midline and distal toenail thickening are transient features which disappear at 24 months.[10] Distal ingrowing can also be seen and is of no importance unless associated with inflammation.[10] Toenail thickening seen under 10 years of age may be due to walking and immature foot muscles leading to pressure and reactive changes.[10] In contrast, the features of deviation and thickening are rarely seen in fingernails and should be evaluated further whenever present.
Congenital And Inherited Disorders
Nail changes in inherited and congenital disorders are nonspecific. The nail can be the primary site of involvement or a part of underlying syndrome. A close examination of nails, skin, and mucosae might help in the diagnosis of these syndromes. These disorders may be classified as follows:[3]
- Genetic disorders restricted to nail apparatus
- Genetic diseases involving nail and skin
- Genetic diseases involving nail and other organs
- Genetic diseases in which nail might be involved.
Genetic disorders restricted to nail apparatus
These correspond to nonsyndromic congenital nail disorders and include trachyonychia, koilonychia, leukonychia, anonychia, hyponychia, distal onycholysis, partial absence of nails, longitudinal streaks, isolated toenail dystrophy, and isolated congenital nail clubbing and rolled nail.[3]
Congenital malalignment of big toenail
It is an isolated condition characterized by lateral deviation of nail plate from the longitudinal axis of the distal phalanx. It is caused either due to an abnormality in the ligament connecting the nail matrix to the periosteum of the distal phalanx or due to an excessive traction by a hypertrophic extensor tendon of the hallux. It is often bilateral and may lead to gross nail deformation, brownish grey discoloration, nail thickening, prominent transverse ridging, onycholysis, triangular shape, and lateral nail fold thickening.[9] Spontaneous resolution is seen in half of the cases.[9] If there is no improvement by the age of 2 years i.e., the nail is not adhered to the nail bed, surgery could be considered.
Genetic diseases involving the nail and associated with skin manifestations only
Epidermolysis bullosa (EB) is a group of inherited mechanobullous disorders characterized by increased skin fragility. It can be simplex (epidermic), junctional, or dystrophic. Nail abnormalities result from blistering and scarring of nail matrix or nail bed and are not type specific. Hemorrhagic onycholysis due to periungual or subungual bullae [Figure 5] is a pointer to EB. Mild nail changes in the form of dystrophic nails, onychomadesis, onychogryphosis are seen in EB simplex.[14] Nail changes are generally more severe in junctional and dystrophic EB. Anonychia, drumstick appearance of the distal digits, hemorrhagic paronychia, and pseudosyndactyly are seen in junctional EB.[14] Total anonychia and mitten deformity of the hands and feet are seen in dystrophic EB. Nail abnormalities may precede skin blistering or may be the only sign of the disease.[9]
Figure 5: Periungual hemorrhagic bullae in dystrophic epidermolysis bullosa
Genetic diseases involving nail and other organs
Majority of the genodermatoses belong to this group.
Nail patella syndrome
Nail abnormalities are evident in 95% at birth, are commonly bilateral and symmetrical involving fingernail.[4] Severity of nail changes decreases from thumb towards the little finger. Micronychia, anonychia, thin or fragile nail plate, Beau's lines, longitudinal ridging, and triangular lunulae are common features.[4] Triangular-or V-shaped lunula (in 90%) alone or in combination with missing dorsal creases of distal finger joint is a characteristic feature.[15] Bilateral posterior iliac horns are pathognomonic.[15] Renal involvement is frequently seen. An early and prompt diagnosis may prevent complications.
Pachyonychia congenita
It is caused by mutations in one of the four keratin genes and has 5 types- Pachyonychia Congenita (PC)-K6a, PC-K6b, PC-K6c, PC-K16, and PC-K17. PC is characterized by thickened dystrophic nails, and painful palmoplantar keratoderma. Early V-shaped thickening of toenail with increased curvature due to nail bed hyperkeratosis is a characteristic feature.[5] The distal two-thirds of the nail plate is thickened with increased transverse curvature and is lifted upwards. The yellow-brown nail along with subungual hyperkeratosis (SUH) give rise to hoof-like nails [Figure 6].[9] At birth, about half of the patients have nail and skin changes.[416] Nearly 75% of the children develop these changes by age of 5 years.[416]
Figure 6: Pachyonychia congenital involving fingernails
Ectodermal dysplasias
Nail abnormalities are nonspecific and are associated with WNT10A mutations and are seen in 20% of the hidrotic ectodermal dysplasias patients.[3] The most common sign is hypoplasia with thickening of the nail plate. Other changes include SUH, anonychia, micronychia, nail plate thinning, brittle nails, koilonychias, or onycholysis.[4]
Incontinentiapigmenti
It is an X-linked dominant neurocutaneous syndrome. Nail involvement in reported in approximately 40%.[17] These include early hypoplastic nail in infancy, koilonychia, yellow discoloration, brittle nails, onycholysis, periungual, and subungual tumors.[17] The fingernails are more commonly affected than toenails.
Porphyrias
Porphyrias are disorders resulting from a defect in heme synthesis. Photo-onycholysis, dystrophic nails, and koilonychia are characteristic nail changes seen in hereditary porphyrias.[18]
Genetic diseases in which the nail might be involved
These include disorders of keratinization, neuro cutaneous syndromes, and others listed in Table 2.[319]
Table 2: Nail changes in genetic diseases
Infections
Onychomycosis
In contrast to adults, children are less often affected. The reported prevalence in children is approximately 0.44% and the incidence ranges from 0.4% to 2.6%.[320] Onychomycosis (OM) is rare in children <2 years of age. Its prevalence has increased in infants and children over the past years. Predisposing factors include tinea pedis, fungal infections in family members, Down syndrome, and other immune-compromised states.[21] Finger nail OM is generally seen in children <3 years[22] and is often caused by Candida albicans [Figure 7].[3] Distal lateral subungual onychomycosis [Figure 8] and superficial white onychomycosis are common clinical presentations[1621] with Trichophyton rubrum as the causative fungus.[21]
Figure 7: Candidal onychomycosis in a 1.5-year-old immune-compromised child
Figure 8: Dermatophytic onychomycosis in a child
Candidal OM may be seen in association with perinatal candidiasis, congenital cutaneous candidiasis, and in children with iatrogenic immunosuppression.[3] Chronic mucocutaneous candidiasis is a rare clinical syndrome characterized by persistent and recurrent candida infections by Candida albicans of the nails, mucous membranes and skin and may be associated with endocrinal and systemic disorders. Nail involvement is often delayed by a few years of age. There is chronic oral candidiasis and paronychia associated with a bulbous distal phalanx due to thickening of the soft tissues. Nail plate is thickened, crumbly, and discolored with hyperkeratotic areas in periungual areas.[3]
The differential diagnoses of onychomycosis in children are enumerated in Box 2. Diagnosis requires laboratory confirmation with direct microscopy and mycological culture.
Box 2: Differential diagnoses of onychomycosis in children
Table 3 summarizes the treatment of onychomycosis in children Treatment in children is challenging with frequent recurrences than adults.[23] There is no formal consensus on systemic antifungal that is Food and Drug Administration approved for pediatric population.[24] Topical and systemic therapy have been used as monotherapy or together.[23] Efficacy and safety profiles of terbinafine, itraconazole, griseofulvin, and fluconazole in children is similar to adult.[25] Even then systemic antifungals should not be used in very young with few involved nails.[24]
Table 3: Treatment of onychomycosis in children
Paronychia
Acute paronychia is inflammation of nail folds caused by bacterial, viral, or fungal infection in children; the most common pathogens being Staphylococcus aureus and β hemolytic streptococcus. Predisposing factors include trauma due to nail biting, finger sucking, nail picking, and hangnails. The affected digit is swollen, erythematous, and tender [Figure 9]. Secondary pus collection can be seen but subungual abscess is rare. Transient damage to the nail matrix can lead to onychomadesis while severe inflammation can lead to total nail dystrophy.[5] Chronic manipulation, infection or inflammation lead to loss of cuticle and manifest as chronic paronychia. Acute painful flares and exacerbations are common and can be managed by compression, drainage and/or oral antimicrobial therapy. In chronic cases, hand care, removal of precipitating factors, and medical management in the form of topical antibiotic and steroid combination is used.
Figure 9: Acute paronychia of thumb
Herpetic whitlow
Finger infection with herpes simplex virus type 1 and 2 is characterized by grouped erythematous vesicles [Figure 10] associated with pain and swelling. It is common in children <2 years and follows direct inoculation from the patient or caregivers or from reactivation of latent virus.[26] It frequently follows an episode of primary herpes labialis.[26] The nail folds involvement lead to acute paronychia while nail bed involvement results in onycholysis and subungual hemorrhage.[4] It is self-limiting but recurrences are common, seen in almost 23%.[26] Early diagnosis and prescription of oral antivirals result in rapid recovery.[9]
Figure 10: Herpetic whitlow
Scabies
Nail involvement in scabies is seen in approximately 6.4% of children.[27] The affected nail is thickened, crumbly, and dystrophic with marked SUH.[28] Nail scabies can be present either alone in immunocompromised children or concurrently with cutaneous lesions of crusted scabies. The affected nails harbor scabies mite and is a source of re-infestation. Treatment is not well defined. Chemical avulsion and application of topical scabicides can be done.
Hand, foot, and mouth disease
Hand, foot, and mouth disease (HFMD) is a common, self-limiting disease in children caused by Coxsackievirus A16 and Enterovirus 71. It is characterized by stomatitis and maculopapular or vesicular rash on palms and soles, extremities, face, and gluteal region. Nail changes are seen in about 20% of patients and the interval between HFMD and onset of nail changes range from 3 to 12 weeks. These include orange discoloration of nail plate, Beau's line, and onychomadesis.[2829] Fingernails are more commonly involved than toenails with 7 being the average number of digits involved.[28] Nail changes are due to a temporary arrest in the nail matrix. The possible mechanisms include nail matrix inflammation due to finger blisters, fever, or viral replication in the nail matrix.[29] Spontaneous recovery occurs in 1-2 months.[28]
Inflammatory Nail Diseases
Psoriasis
Nail involvement in psoriasis is rare in children as compared to adults with a prevalence ranging from 10% to 40%.[5] It may occur in isolation, precede, or develop simultaneously with skin lesions. Nail pitting is the most common finding, seen prominently on fingernails [Figure 11]. The pits are irregular and deep.[30] Other features include thickened nails, leukonychia, Beau's lines, and onycholysis with SUH.[31] Longitudinal ridges, splinter hemorrhages, and oil drop sign are less frequent. Trachyonychia may also appear in childhood nail psoriasis.[31] Nail involvement in childhood is associated with male sex, palmoplantar psoriasis, severe disease and psoriatic arthritis.[32] Treatment varies according to the severity and pattern of involvement. Topical treatment include combinations of high potency topical steroids and calcipotriene or tazarotene, applied for 3 months or more.[3] Low concentration (1 mg/ml) of intralesional triamcinolone can be given for individual nails.[3] Systemically, cyclosporine and biologic agents, such as tumor necrosis factor-α inhibitors, are more effective than methotrexate, retinoids, and narrowband ultraviolet (UV)-B.[3]
Figure 11: Coarse irregular pits of nail psoriasis
Lichen planus
The Prevalence of nail lichen planus (NLP) in children ranges from 14% to 20%.[33] Children with NLP have more associations with other immunologic skin or systemic disorders such as alopecia areata (AA) and thyroid as compared to adults.[34] Nail plate thinning and longitudinal ridging are the most common findings.[33] Trachyonychia, pitting, discoloration, nail dystrophy, onycholysis, nail splitting [Figure 12] and leukonychia have also been reported. NLP can have three different presentations-typical NLP, twenty nail dystrophy (TND or trachyonychia), and idiopathic atrophy of the nails.[34] Dorsal pterygium formation is rare in children. Idiopathic atrophy of the nails has a rapid course and is associated with destruction of nail matrix and scarring. This form is more common in Indians and is exclusively seen in children.[34] Typical NLP in children generally responds to high potency topical steroid and a 6–12-week course may be tried.[3] Other options are systemic steroid alone or followed by methotrexate, hydroxychloroquine, acitretin, and narrowband UV-B. Trachyonychia resolves spontaneously and does not warrant active intervention except liberal use of emollients.[3]
Figure 12: Nail thinning and splitting in lichen planus
Lichen striatus
Nail involvement in lichen striatus (LS) is uncommon and is exclusively seen in children. Longitudinal ridging, fissuring, splitting, and thinning of nail plate are common features.[35] Nail changes generally continue with linear skin lesions. They may develop before, simultaneously or after skin lesions.[36] Isolated nail LS has also been reported. The diagnosis of nail LS should be suspected when a child presents with nail abnormalities localized to the lateral or medial portion of a single nail.[35] The treatment is generally not necessary, but resolution may take a prolonged course of 6 months to 5 years.[30]
Atopic dermatitis
Fingernails are shiny and buffed due to constant rubbing in chronic atopic dermatitis (AD). Nail changes are nonspecific and include transverse grooves, hyperpigmented nail folds and faint longitudinal pigmented bands.[3] The existence of nail ridging in specific V arrangement as seen in chevron nail with atopy has been reported.[37] Irregular transverse groove are commonly seen during acute flares due to cuticle disruption and nail matrix inflammation. These may improve on applying high potency topical steroid to the affected nail folds.[3]
Alopecia areata
The reported prevalence of nail changes ranges from 26% to 30%.[3839] They are usually seen with extensive disease or in association with autoimmune diseases.[3] The common changes are geometric regular pitting [Figure 13] and trachyonychia.[30] Other clinical findings include Beau's lines, punctate erythronychia of lunula, longitudinal erythronychia, or leukonychia and onychomadesis.[3] Nails usually revert to normal within 6 months of treatment of AA.
Figure 13: Regular pitting in a girl with extensive alopecia areata
Trachyonychia
It is also known as TND of children. Trachyonychia is a self-limiting, morphological entity characterized by thin nails with longitudinal ridging, nail plate roughness, opacity, and sand paper appearance [Figure 14]. There is often associated koilonychia and cuticle hyperkeratosis. Any number of nails may be involved and degree of severity may vary in different nails. It can be idiopathic or associated with dermatological diseases such as alopecia areata (AA), psoriasis, lichen planus, and eczema. In children, it is mostly idiopathic or associated with AA.[40] Whatever may be the cause, course of trachyonychia is always benign; hence, there is no need for biopsy.[34] Frequent emollients are generally sufficient; however, topical steroids and retinoids can be used if required.[34] Underlying cause should be treated wherever present.
Figure 14: Trachyonychia of all fingernails
Tumors
Warts
Warts are most common benign nail tumors in children caused by different genotypes of human papillomavirus. Fingernails are frequently affected due to nail biting and picking. Warts may be periungual presenting as verrucous hyperkeratotic lesions involving nail folds [Figure 15], or subungual.[5] Direct involvement of nail matrix is rare. Spontaneous regression is seen in 30% of cases. Treatment may be necessary to prevent spread. Keratolytic agents such as salicylic acid, lactic acid, or trichloroacetic acid may be effective. Intralesional bleomycin is painful but gives good results in recalcitrant warts. Recurrences and nail scarring are common with surgical treatment (cryotherapy, radiofrequency and laser ablation).
Figure 15: Multiple subungual and periungual warts on hands
Exostosis
It is a benign osteochondral tumor of the distal phalanx of fingers and toes, mainly great toe. Subungual exostosis is common in adolescents and young adults but is rarely seen in children <10 years of age.[41] It presents with a firm, fixed subungual growth, or nodule with normal or hyperkeratotic surface. The lesion may ulcerate, become painful, give rise to ingrown nail or mimic subungual wart.[9] There is associated nail dystrophy and onycholysis. A pedunculated exophytic lesion arising from the phalanx is seen on radiographs of affected part. Treatment is surgical excision.[42]
Infantile Digital Fibromatosis/Reye's Tumor
Infantile digital fibromatosis (IDF) is a rare benign, asymptomatic, fibroblastic proliferation that generally presents in 1st year of life as a smooth pinkish nodule overlying distal phalanx of fingers and toes.[43] It is characterized histologically by eosinophilic intracytoplasmic inclusion bodies and has a tendency to resolve spontaneously.
Nail matrix nevi, melanoma, and melanonychia striata
Longitudinal melanonychia or melanonychia striata presents as a sharply demarcated longitudinal pigment band of even width along the nail plate [Figure 16a]. Its prevalence in adults varies among racial groups and is more common in darker-skinned individuals.[24] In children, the prevalence is low with only case reports and series been described in literature.[4445] Unlike adults, it is associated with benign stable melanocytic proliferations in childhood.[44] Nevi and lentigo are the common causes followed by functional or atypical melanocytic hyperplasia. Nail matrix nevi may be present at birth or may develop at 2–4 years of age and present as melanonychia and pseudo-Hutchinson's sign [Figure 16b].[46] Melanoma is extremely rare in children.[46] Most cases of melanonychia striata are managed conservatively and biopsy is restricted for select cases. Increasing width or darkening of the lesion, pigment variegation, periungual pigmentation, or nail dystrophy require confirmatory histopathology.[4447]
Figure 16: Clinical picture (a) and dermoscopy with pseudo-Hutchinson's sign (b) of longitudinal melanonychia due to nail matrix nevus in a child
Traumatic
Onychophagia
It has been discussed already. Exact etiology is unknown but is believed to be a subgroup of obsessive-compulsive disorder, anxiety disorder, and reflection of particular emotional state.[48]
Finger sucking
The behavior generally starts in infancy and ceases after 6 years of age.[49] It generally requires no treatment till 2 years of age. Secondary nail dystrophy may be seen.
Nail picking
It is the damage to nail plate by sharp objects resulting in pits, onychoschizia, pterygium formation, and anonychia. Cuticle picking is seen in children with dry cuticles.
Habit tic deformity
It results from habitual external trauma to the nail matrix. The constant pushing of cuticle at the PNF results in nail matrix damage and manifests as series of transverse depression from proximal to distal end, similar to medial canalicular deformity.[48] The cuticle is lost, lunula elongated/pyramidal and PNF is thickened. Fingernails, especially thumbnails, are involved but habit tic deformity of toenails has recently been described.[50] Treatment consists of complete cessation of the habit following which nail changes revert completely.
Juvenile ingrown nails
Lateral ingrowing is seen in teenagers and adolescents. The precipitating factors include mal-alignment, tight footwear, hyperhidrosis, faulty trimming, and habitual manual picking of soft nails.[910] All these lead to inflammation, granulation tissue formation, tissue hypertrophy and secondary infection.[9] Conservative treatment in early stages include taping, gutter splints, curettage or silver nitrate application to the granulation tissue along with systemic antibiotics.[51] In advanced cases, phenolization of lateral matrix is the treatment of choice.[10]
A comprehensive list of nail changes due to drugs and systemic disease has been given in Table 4.[352]
Table 4: Nails changes in pediatric systemic diseases and due to drugs
Nutritional deficiencies may also be associated with nail changes [Table 5].[3]
Table 5: Nails in nutritional deficiencies
Conclusions
Physiological nail changes are common in neonates and infants. It is mandatory for dermatologists to be well acquainted with these changes to reassure the parents. Trachyonychia, nail psoriasis, and lichen planus may lead to nail dystrophy. Nail changes may be a clue to underlying genetic syndrome or systemic disorders. Detailed clinical history, careful clinical examination of nails, skin, and hair is essential to make correct diagnosis, impart appropriate management, and prevent complications.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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