Itchy skin conditions include:Allergy & anaphylaxisAthletes footAtopic dermatitisContact dermatitisDrug allergyErythema multiformeFolliculitisImpetigoInsect bites, stings, infestationsKawasaki diseaseLichen planusNummular eczemaPityriasis roseaPsoriasisScabiesTinea corporisToxic epidermal necrolysisUrticariaVaricellaViral exanthemNote: Miliaria rubra is itchy, miliaria profunda usually isn’t.

The baby most probably has dystrophic epidermolysis bullosa, a primarily autosomal dominant disorder associated with keratin 5 and 14 defects. Initial management consists of supportive measures such as protecting the skin.

Hypopigmentation refers to a decrease in the amount of the pigment melanin in the skin, which leads to an abnormally lighter skin tone. Hypopigmentation can be generalized or localized. Generalized hypopigmentation occurs in albinism or can be ethnicity related. Causes of localized hypopigmentation include Incontinentia pigmenti, Lichen planus, Tuberous sclerosis, Piebaldism, vitiligo, and leprosy. Celiac disease is not associated with hypopigmentation.

Alopecia is a scalp condition characterized by either overall baldness or patches of hair loss over the head. It can be broadly classified as scarring alopecia and non-scarring alopecia. Non-scarring is the most common type and is seen in various conditions like nutritional deficiencies, alopecia areata, hypothyroidism, tinea capitis, and SLE. Scarring alopecia is commonly seen in cases of discoid lupus erythematosus, which is a common cause of widespread inflammatory and scarring lesions all over the body and scalp.

According to the Gell and Coombs classification of hypersensitivity reactions, the scenario provided is a type 4 (delayed) reaction.These reactions are mediated by T lymphocytes and cause contact dermatitis. Nickel, commonly found in cheap jewellery, is a common cause of contact dermatitis.Note:There are two main types of contact dermatitis:- Irritant contact dermatitis: It is a common, non-allergic reaction due to weak acids or alkalis (e.g. detergents). These are often seen on the hands. They present typically with erythema, and rarely, crusting and vesicles.- Allergic contact dermatitis: These are type IV hypersensitivity reactions and are often seen on the head following hair dyes.They typically present as acute weeping eczema which predominately affects the margins of the hairline rather than the hairy scalp itself. Treatment is usually with a potent topical steroid.Other options:- Allergic rhinitis is an example of a type 1 (immediate) reaction. It is an IgE mediated. It is a hypersensitivity to a previously innocuous substance.- Type 2 reactions are mediated by IgG and IgM, which binds to a cell, causing cell death. Goodpasture syndrome is an example of a type 2 hypersensitivity reaction.- Immune complexes mediate type 3 reactions. Rheumatoid arthritis is an example of a type 3 hypersensitivity reaction.

Histology of psoriasis is characterised by parakeratosis (cell nuclei within stratum corneum) and thickened projections of the prickle cell layer of keratinocytes (psoriasiform hyperplasia or acanthosis). Orthokeratosis refers to the formation of a pathological anuclear keratin layer in the skin.The stratum granulosum is actually thinned or absent in patients with psoriasis.

Pityriasis amiantacea: This condition is characterized by thick, asbestos-like scales on the scalp and is often associated with psoriasis or seborrheic dermatitis.

Infantile seborrhoeic dermatitis: Also known as cradle cap, this condition causes greasy, yellowish scales on the scalp.

Tinea capitis: A fungal infection of the scalp that leads to scaling, hair loss, and sometimes redness and swelling.

Cutaneous lupus erythematosus: While lupus can cause skin lesions, it is less commonly associated with a scaly scalp compared to the other conditions listed. It can cause hair loss and erythema, but significant scaling is not a primary feature.

Scalp psoriasis: This condition is well-known for causing thick, silvery scales on the scalp

“Tinea incognito” is a term used to describe a tinea infection modified by topical steroids. It is caused by prolonged use of topical steroids, sometimes prescribed as a result of incorrect diagnosis. Topical steroids suppress the local immune response and allow the fungus to grow easily. As a result, the fungal infection may take on the bizarre appearance seen in this patient.The diagnosis of tinea incognito is simple to confirm by microscopic visualization of branching hyphae and spores typical of dermatophytes in a potassium hydroxide preparation.Treatment of tinea incognito requires cessation of all topical steroid use and implementation of specific antifungal treatment. A low-potency corticosteroid may be used briefly to avoid the flare often associated with abrupt cessation of a potent steroid. Patients should be warned of this possibility so they do not reinstitute use of topical steroids on their own.

The skin lesion described is the typical presentation of a keloid scar.Keloid scars extend beyond the limits of the incision.Note:Surgical wounds are either incisional or excisional and either clean, clean-contaminated or dirty. The main stages of wound healing include:- Haemostasis:It occurs minutes to hours following injury. It is characterised by the vasospasm in adjacent vessels, platelet plug formation and generation of fibrin rich clot.- Inflammation: It occurs typically 1-5 days after the injury. Neutrophils migrate into the wound (this is often impaired in diabetes). Growth factors, including basic fibroblast growth factor and vascular endothelial growth factor, are released in this phase. Fibroblasts replicate within the adjacent matrix and migrate into wound, while macrophages and fibroblasts couple matrix regeneration and clot substitution.- Regeneration: It occurs typically between 7-56 days after the injury. The factors that stimulate this phase are platelet-derived growth factor and transforming growth factor. They stimulate fibroblasts and epithelial cells. Fibroblasts produce a collagen network. Furthermore, they cause angiogenesis and thus wound healing.- Remodelling: This is considered the longest phase of the healing process and may last up to one year (or longer). During this phase, fibroblasts become differentiated (myofibroblasts), and these facilitate wound contraction. Collagen fibres are remodelled, and microvessels regress, leaving a pale scar.Clinical correlation:Abnormal scar formation:- Hypertrophic scars:It is the condition where excessive amounts of collagen are produced within a scar. Nodules may be present histologically containing randomly arranged fibrils within and parallel fibres on the surface. The tissue itself is confined to the extent of the wound itself and is usually the result of a full-thickness dermal injury. They may go on to develop contractures.- Keloid scars: This is also a condition where excessive amounts of collagen occur within a scar. A keloid scar will typically pass beyond the boundaries of the original injury. They do not contain nodules and may occur following even trivial injury. They do not regress over time and may recur following removal.

The sign being elicited in this patient is Nikolsky’s sign. Based on the findings, the patient is suffering from toxic epidermal necrolysis.Nikolskys sign: Rubbing the skin causes exfoliation of the outer layer and usually blistering within a few minutes. Other options:- Cullen’s sign: Periumbilical bruising due to intra-abdominal haemorrhage. If the discolouration is seen in the flanks, it is called Cullen’s sign. Underlying pathology includes ruptured ectopic pregnancy and haemorrhagic pancreatitis. – Forscheimer’s sign: It is a fleeting exanthem that is seen as small, red spots (petechiae) on the soft palate. Associated with rubella and glandular fever. Gorlin’s sign: It is the ability to touch the tip of the nose with the tongue. Increased incidence in children with connective tissue disorder, e.g. Ehler Danlos syndrome. – Auspitzs sign: These are small bleeding points are left behind when psoriatic scales are lifted off. It is not a very sensitive or specific sign. Other cutaneous signs include:- Hair collar sign: It is a collar of hypertrichosis around an area of cranial dysraphism.- Hertoghe’s sign (Queen Anne’s sign): It is the loss of lateral one-third of eye-brows. It is associated with numerous conditions, including lupus, HIV, and hypothyroidism. – Dariers sign: It is the swelling, itching and erythema that occurs after stroking skin lesions of a patient with systemic mastocytosis or urticarial pigmentosa. – Dermatographism: Rubbing the skin causes a raised, urticarial lesion. – Koebners phenomenon: It is the appearance of new skin lesions in areas of trauma.- Breakfast, lunch, and dinner sign: Linear pathway of a group of three to five papules caused by the common bed bug, Cimex lectularius. – Buttonhole sign: In type 1 neurofibromatosis, neurofibromas can be invaginated with the finger back into the subcutis. The nodule will reappear after the release of pressure. The sign is also positive for dermatofibromas. – Crowe’s sign: Axillary freckling seen in type I neurofibromatosis.

Scabies infection in neonates typically manifests as nodular eruptions involving the face, neck, scalp, palms, and soles in contrast to the predominant involvement of the hands, wrists, elbows, and ankles in adults. Differential diagnoses for the nodular eruption in neonates are broad, and scabies often is misdiagnosed as Langerhans cell histiocytosis, urticaria pigmentosa, or another pruritic, bullous, or lymphoproliferative dermatosis. Histopathology of the reactive nodules usually is not diagnostic, because scabetic organisms are often unidentified and histologic findings are nonspecific. Furthermore, because of the atypical presentation, scabies in children is often missed until persons in close contact with the child present with similar symptoms. Thus, a thorough history and close follow-up are crucial to avoid misdiagnosis and unnecessary aggressive treatment. Moreover, synchronized treatment of patients and their close contacts is needed to ensure the success of therapy, considering that relapse is 2-3 times more frequent in children and infants

Erythema nodosum (EN) is an acute, nodular, erythematous eruption that usually is limited to the extensor aspects of the lower legs. Chronic or recurrent erythema nodosum is rare but may occur.Currently, the most common cause of erythema nodosum is streptococcal infection in children and streptococcal infection and sarcoidosis in adults.The eruptive phase of erythema nodosum begins with flulike symptoms of fever and generalized aching. Arthralgia may occur and precedes the eruption or appears during the eruptive phase. Most lesions in infection-induced erythema nodosum heal within 7 weeks, but active disease may last up to 18 weeks. In contrast, 30% of idiopathic erythema nodosum cases may last more than 6 months. Febrile illness with dermatologic findings includes abrupt onset of illness with initial fever, followed by a painful rash within 1-2 days.

Gilbert’s syndrome is an autosomal recessive condition that results from defective bilirubin conjugation due to a deficiency of UDP glucuronyl transferase – 1. The prevalence is approximately 1-2% in the general population.The clinical presentation of Gilbert’s syndrome include:- Unconjugated hyperbilinaemia- Jaundice can occur during an intercurrent illnessManagement:Blood investigations usually reveal a rise in bilirubin following prolonged fasting or intravenous nicotinic acid.No treatment required for these patients.Other options:- CYP2C9 deficiency causes reduced warfarin metabolism, and subsequent enhanced drug effects. – Pancreatic disease, cholestasis, excessive alcohol consumption and certain drugs are common causes of raised GGT levels- Defective hepatocyte excretion of conjugated bilirubin is related to the pathophysiology of Dubin-Johnson syndrome- Reduced CYP2C19 levels can lead to the disordered metabolism of clopidogrel and other drugs such as proton-pump inhibitors, anticonvulsants and sedatives.

Lesions caused by herpes simplex virus may appear in various clinical stages. They are usually the result of an HSV-1 infection and they may appear on the face and neck. They start as fluid-filled blisters which eventually erupt into small painful ulcers.

Erythema nodosum (EN) is an acute, nodular, erythematous eruption that usually is limited to the extensor aspects of the lower legs. It is a delayed hypersensitivity reaction to a variety of antigens| circulating immune complexes have not been found in idiopathic or uncomplicated cases but may be demonstrated in patients with inflammatory bowel disease.Currently, the most common cause of erythema nodosum is a streptococcal infection in children and streptococcal infection and sarcoidosis in adultsIn most patients, erythema nodosum is a self-limited disease and requires only symptomatic relief using nonsteroidal anti-inflammatory drugs (NSAIDs), cool wet compresses, elevation, and bed rest.

Scarlet fever is a childhood infectious disease caused by group A Streptococcus. It produces a papular rash, which is classically described as a sand-paper rash. The rash initially appears on the trunk, groin, and underarms and then spreads to extremities, usually sparing the palms and soles. Circumoral area is also spared, giving it pallor-like appearance. Diseases like erythema multiforme, contact dermatitis, staphylococcal scalded skin syndrome, and rubella produce a rash that classically affects the palms and soles.

Alopecia areata is seen in 6-8.8% of patients with Down syndrome, but only 0.1% of patients with alopecia areata have Down syndrome. The high frequency of alopecia areata in patients with Down syndrome suggests that a genetic linkage for alopecia areata may exist on chromosome 21.

The clinical presentation of lichen planus has several variations, as follows:- Hypertrophic lichen planus- Atrophic lichen planus- Erosive/ulcerative lichen planus- Follicular lichen planus (lichen planopilaris)- Annular lichen planus- Linear lichen planus- Vesicular and bullous lichen planus- Actinic lichen planus- Lichen planus pigmentosus- Lichen planus pemphigoides

When topical agents are insufficient or not tolerated, or in cases of moderate to severe acne, especially when the chest, back and shoulders are involved, systemic antibiotics are often considered the next line of treatmentSystemic antibiotics should not be used to treat mild acne because of the risk of increasing resistance. The additional use of nonantibiotic topical agents in combination with oral antibiotics should be considered. Topical retinoids with oral antibiotics may give a faster response and be more effective than either drug used alone.Treatment with tetracyclines and erythromycin reduces P. acnes within the follicles, thereby inhibiting the production of bacterial-induced inflammatory cytokines. These agents also have inherent anti-inflammatory effects, such as suppressing leukocyte chemotaxis and bacterial lipase activity.

Hypopigmentation is a side-effect that is more likely to be due to eczema rather than topical steroids therapy.All the options provided are potential side-effects of topical steroid therapy. They are observed when the potency of the steroid used is too high, or the amount of drug used is too much.. FTU or fingertip unit application is what is recommended, with caution, in delicate areas such as the face. Hypopigmentation can occur in eczema and is a post-inflammatory response, in contrast to the total depigmentation which is seen in vitiligo. Chronic eczema causes lichenification of skin, where the epidermis is thickened, and not skin atrophy.

Lichen sclerosus is a common chronic skin disorder that most often affects genital and perianal areas. LS typically presents with vulval itching and clinical findings of pallor, epidermal atrophy (cigarette paper wrinkling), purpura, and/or erosions.Lichen sclerosus (LS) and lichen planus (LP) are both immunologically mediated diseases with a preference for the genitalia. The main difference between the two conditions is that LP has a propensity to involve the mucous membranes including the mouth and vagina which are rarely affected in LS.

The most common cause of acute urticaria is a viral infection. Individual lesions typically are short-lived and last less than 24 hours. Urticaria can be due to or can be made worse by cold temperatures. One of the other causes of urticaria is salicylic acid.

Erythema multiforme lesions typically heal without scarring. Other options:- In erythema multiforme, lesions are typically symmetrical and acral, i.e. on the hands, feet and limbs. – HSV is a common cause of erythema multiforme in children, accounting for at least 50% of cases| the lesions typically have damaged skin in the centre and are dusky and bullous (in contrast to urticaria, where the centre of the lesion is normal).

Miliaria is a common skin disease caused by blockage and/or inflammation of eccrine sweat ducts. Miliaria is frequently seen in hot, humid or tropical climates, in patients in the hospital, and in the neonatal period. Miliaria is also known as sweat rash.Based on the level of the sweat duct obstruction, miliaria is divided into three subtypes:- Miliaria crystallina (sudamina), caused by obstruction of the sweat ducts close to the surface of the skin (epidermis)|- Miliaria rubra, caused by obstruction of the sweat ducts deeper in the epidermis|- Miliaria profunda (tropical anhidrosis), the result of sweat leaking into the middle layer of skin (dermis).Miliaria crystallina appears as 1–2 mm superficial clear blisters that easily break. The blisters can look like beads of sweat. There is no inflammation. The blisters are usually seen widely spread on the head, neck, and upper trunk.Miliaria rubra is the most common type of miliaria results in red, 2–4 mm, non-follicular papules and papulovesicles. They are very itchy. Background erythema is often present. In children, miliaria affects the skin folds of the neck, axilla or groin. In adults, miliaria often affects the upper trunk, scalp, neck and flexures, particularly areas of friction with clothing. Miliaria pustulosa is a variant of milia rubra in which there are pustules.Miliaria profunda describes asymptomatic deep papules. The flesh–coloured, 1–3 mm diameter papules usually arise on the trunk and extremities.Mild Topical steroids can be used as a treatment

Erythema Migrans is associated with Lyme disease, a tic transmitted infection caused by the spirochete Borrelia Burgdorferi. The rash usually appears at the bite site after 7 to 10 days. It is flat or slightly raised and migrates as the name suggests. Streptococcal throat infection and Crohn’s disease are both associated with erythema nodosum.Herpes simplex and Rheumatic fever may present with Erythema Multiforme and Erythema Marginatum respectively.

Eczema herpeticum (also called Kaposi varicelliform eruption) is a disseminated viral illness usually associated with lymphadenopathy.It is most often caused by Herpes Simplex type 1 or type 2. Occasionally, other viruses such as coxsackievirus A16 may cause eczema herpeticum. Affected children usually develop itchy blisters and fever after coming in contact with an affected individual who may or may not display cold sores.It is characterised by an itchy and sometimes painful cluster of blisters most commonly on the face initially. This spreads over one to several weeks resulting in further crops of blisters which can become confluent. Lymphadenopathy and fever are common in these patients.The severity varies from mild illness to life-threatening, especially in immunocompromised children or young infants. It is markedly more common in children with atopic dermatitis. It is one of the few dermatological emergencies, and oral antivirals are often indicated. Referral to an ophthalmologist may be needed if there is eyelid or eye involvement. Occasionally, superadded skin infections caused by staphylococci and streptococci can occur.

The most common organism responsible for tinea capitis is Trichophyton tonsurans.Tinea is a term given to dermatophyte fungal infections. There are three types of tinea, depending on what part of the body is infected:- Tinea capitis – scalp- Tinea corporis – trunk, legs or arms- Tinea pedis – feetTinea capitis (scalp ringworm):It is a cause for scarring alopecia mainly seen in children.If untreated, it can form a raised pustular, spongy/boggy mass called a kerion.The most common cause of tinea capitis in the UK and the USA is Trichophyton tonsurans.Tinea can also be caused by Microsporum canis acquired from cats or dogs.The diagnosis of tinea capitis and identification of the organism is possible from the skin lesions:- Scalp scrapings and Potassium hydroxide (KOH) mounts.- Wood’s lamp: Microsporum canis produces a green fluorescence under Wood’s lamp examination.Treatment: – Oral antifungals: terbinafine for Trichophyton tonsurans infections.- Griseofulvin for Microsporum infections. – Topical ketoconazole shampoo is recommended for the first two weeks to limit the transmission of the infection.

Koebner’s phenomenon describes skin lesions that occur on damaged skin, usually in a linear fashion at the site of injury. Conditions which exhibit true Koebnerisation include psoriasis, lichen planus, lichen sclerosis, vitiligo, Kaposi sarcoma and SLE. Conditions such as erythema nodosum or multiforme, or Lyme disease and Impetigo do not exhibit Koebner’s phenomenon.

Erythema nodosum is the most common type of inflammation of the subcutaneous fat tissue, referred to as panniculitis. Erythema nodosum appears as painful, erythematous round lumps, usually symmetrically on the anterior aspect of lower extremities. These lesions are self-limiting and tend to resolve within 2-8 weeks without undergoing necrosis. There are various causes of erythema nodosum, but the most important among children is the streptococcal throat infection. Other causes include autoimmune conditions like sarcoidosis, inflammatory bowel disease, mycobacterial infection (TB), and drugs like penicillin and sulphonamides. Coeliac disease is not linked with the formation of erythema nodosum.

Atopic dermatitis is an allergic condition which is more apparent in those children who have a positive family history in their 1st or 2nd degree relatives. In some cases, there might be a positive history of bronchial asthma. The best treatment option in this case would be topical application of 1% hydrocortisone ointment to the affected areas of the child. We cannot prescribe a strong ointment to the face because it may lead to skin atrophy, telangiectasia and other steroid related topical complications.