A 15 year old guy presented with itchy lichenoid papules and plaques and plaques over extensor surfaces of forearms and legs accompanied by severe itching and sleeplessness (you can see below pic) the skin lesions were present for 2 months and did not respond to moisturization and application of mometasone furoate cream. The primary diagnosis by the referring physician was lichen planus. However he had been trated in her infancy and preschool years for flexural lesions of atopic dermatitis with medications.
Atopic Dermatitis in children can often present predominantly with atypical manifestations. Failure to recognize the atypical features of AD may result in misdiagnosis and delay in instituting appropriate management.
AD is a syndrome. We do not have a universally accepted definition of AD. The Hanifin and Rajka criteria and the criteria proposed by the UK working group are commonly used for the diagnosis of AD. Specificity and sensitivity of them is highly dependent on the tested populations. Strict adherence and over reliance on these criteria for diagnosis AD may resukt in under recognition of many of the atypical manifestations of AD. Many of the atypical manifestations is dependent on racial, and geographic factor. Any child presenting with three of the features included in the minor criteria of Hanifin and Rajka should be strongly suspected to have AD, ever if major criteria is not fulfilled.
Atypical presentation of AD can be broadly categorised in to the followinng groups:
- AD presenting with morphological
- AD presenting in unusual locations
- AD presenting with regional variants
AD Presenting With Morphological Variants
Lichenoid Atopic Dermatitis
The typical presentaion of lichenoid AD is illustrated in the case report. AD presenting with lichen planus like skin lesions has been described in African , Americans with fitzpatrick skin types 5 and 6. Skin lesions otherwise resembling lichem planus were seen on extensor aspects of the limbs. However, skin biopsy showed spongiosis and exocytosis accompanied by sparse perivascular lymphocytic innfiltrate in the dermis with an occasional eosinophil. The typical histopathological features of lichem planus were absent. This entity is unlikely to be recognised without high index of suspicion absence of wickham striac in the skin lesions is a useful clinical clue. Skin biopsy is often required to establish the diagnosis.
AD can present with prurigo like lesions. This presentations is often accompanied by extremely itchy episodes at night with sleeplessness. Chest, abdomen, axillae are the commonly involved sites. Lichenification of the lesions is a very common occurrence. Early recognition is vital for appropriate care. Phototherapy has proven efficacy, as shown by a recently conducted randomised control study.
AD presenting with nummular lesions often has a chronic relapsing course. plaques studded with exudative papules are seen in the extensor aspects of limbs, dorsum of hands, trunk, sparing the face. This is the most common atypical morphological variant of AD. Nummular lesions were seen in 76.5% of children in a recently reported study. Systemic foci of staphylococcus aureus infecction in the ear, nose, throat, or lungs is a known trigger. Patch testing is helpful for ruling out contact dermatitis in children presenting with nummular lesions as there is a chance of co-existing nickel or chromium contact dermatitis which often present with nummular dermatitis.
AD With follicular lesions
AD presenting with profuse eruption of follicular papules and plaques with follicular prominence is a well acknowledge feature in asian children. Other morphological variants of AD include patchy pityriasifrorm lichenoid eczema, and juvenile papular dermatosis. AD can resemble lichen nitidus as well.
AD presenting in unusual locations
Children habituated to thumb sucking may present with eczematous patch in the thumb in addition to skin lesions involving the classical sites of AD. The pH of saliva (7.42+or-0.04) is greater than normal pH of skin (range 4 to 5.5) and may contribute to premature breakdown of stratum corneum by activating the serine esterases which have pH optima in the alkaline range.
Eczema with typical morphology and age specific distribution pattern is a requirement for diagnosis AD according to the criteria proposed by the UK working group and American Academy of Dermatology. Historically sparing of axilla, groin and diaper area is considered to be a consistent feature of AD. However, AD can manifest in sites such as axilla, groin and buttock, AD involving axilla or groin is often misdiagnosed and underappreciated. AD in infant typically spares the diaper area. The nose and paranasal areas are spared even in severe AD.
Recent publications have focused on the role of microbiome as a major driving factor in the pathogenesis of AD. The involved skin in AD shows loss of microbial diversity. staphyloccocus aureaus and staphylococcus epidermis are overexpressed, with simultaneous under erxpression of microorganisms such as propionibacterium, corynebacterium and streptococcus. acute AD shows much higher colonization with staphylococcus aureus compared to chronic AD. Axilla, groin, anterior nares are the most heavily colonized sites.
Excessive sweating and colonization by staphylococcus aureus may be the underlying predisposing factor in children who have predilection for developing AD in Axilla and groin. The inflammation induced by sweat is attributed to Dermicidin, an antimicrobial protein present in sweat and known to possess proinflammatory activity.
AD Presenting With Regional Variants
AD can present as a localized minimal variants restricted to lips, nipple or eyelids. Localised involvement such as earlobe rhagades or rhagades of the nasal orifices in association with rhinitis may be the only manifestation of AD in some children.
AD is a disease with seasonal fluctuations in severity. Milld AD in children may show temporal remission, necessitating a need for repeated clinical examination to recognise AD in children presenting with minimal variants.
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