A3-year-old child presents with eczematous dermatitis over the extensor surfaces. His mother has the history of bronchial asthma. What should be the most probable diagnosis?

Ans. a. Atopic dermatitis Most probable diagnosis in a 3-year old child, who presents with eczematous dermatitis over the extensor surfaces with family history of bronchial asthma is atopic dermatitis.Atopic Dermatitis (AD)* AD is a cutaneous expression of the atopic state, characterized by a family history of asthma, hay fever or dermatitis in ~ 70% of patients.Etiopathogenesis:* Genetic predisposition: When both parents are affected, over 80% and when only one parent is affected ~50% of their children manifest the disease* Increased IgE synthesis; increased serum lgE; increased specific IgE to food, aeroaliergens. bacteria and bacterial products.* Increased expression of CD23 (low affinity IgE receptor) on monocyte and B- cells* Impaired delayed type hypersensitivity reactions.Clinical Presentation:* The clinical presentation varies with the age, half of the patients present within the first year of life, and 80% presents by 6 years of age.* The infantile pattern is characterized by weeping inflammatory patches and crusted plaques that occur on face, neck and extensor surfaces (Infantile eczema)* The childhood and adolescent pattern is marked by dermatitis of flexural skin particularly in antecubital and popliteal fossa.* Clinical course lasting longer than 6 weeksQ.* AD may resolve spontaneously, but over half of affected children will have dermatitis in adult life, i.e. course is marked by exacerbation and remissions.Pruritus and Scratching Made Worse by* Environmental alterations* Denny Morgan fold (Extra-fold of skin beneath lower eyelid).* Change in temperature, sundry (In rainy season) and rough (woolen) clothing and leading to excoriation, lichen if ication, dryness.* Increased tendency for vasoconstriction like perioral pallor and White dermatographismy.Atopic Dermatitis Associated with* Alopecia areatac* Susceptibility to skin infections0,* Antenna sign (Follicular openings are filled with horny plugs)* Head light sign (Inflammation of skin on and around lips)* Hertoghe's sign (Thinning of lateral half of eyebrows) Clinical Phase of Atopic DermatitisInfantile phaseChildhood phaseAdult phase* Rarely starts before 4-6 weeks of age and usually begins between 2-3 months of age* First begin on face0 and may quickly spread to other areas. Although, often then napkin area is relatively spared, as a result of the area being kept moist.* From one and half to two years onwards* Most characteristically involve elbow and knee flexures, wrist and ankle.* Sides of neck show a reticulate pigmentation known as atopic dirty neck.* Lichenification. especially of flexures and hands (similar to that in later childhood)* Involvement of vermilion of lip (like dermatitis)Atopic Dermatitis (AD)Clinical phase of Atopic Dermatitisinfantile phaseChildhood phaseAdult phase* Excoriation and lichenification appear at about 6 months of age, when the ability to scratch develops* Initially the disorder involves flexural distribution But when the child starts to crawl, the exposed extensor aspect of knees, are most involved.* Uncommon extensor distribution and inability to lichenify (even after prolonged rubbing) are very' difficult to treat and take longer time to remit.* Nipple involvement in young / adolescent women* Photosensitivity with ultraviolet and infrared radiation. Hanifin and Rajka Diagnostic Criteria for Atopic Dermatitis(Three major and three minor criteria should be present)Major criteria Minor criteria* Pruritus * Involvement of face and convexities in infants {<2 years) and distribution over flexures (popliteal and antecubitai fossa) in older children.,* Tendency to chronicity * Personal or family history of atopy such as asthma, allergic rhinitis or atopic dermatitis* Facial pallordeg/suborbital shadowing* Infra orbital fold (Dennie's line)* Recurrent skin infections (pyoderma, warts molluscum contagiosum)* Ichthyosis vulgaris with accentuation over palmar crease\* Tendency to non specific dermatosis of hand* Immediate skin test* Delayed blanching to cholinergics* Raised serum total IgE* Anterior subcapsular cataract * Keratoconus