Keratosis pilaris most often affects the outer aspect of both upper arms. It may also occur on the thighs, buttocks and sides of the cheeks, and less often on the forearms and upper back. The distribution is symmetrical.The scaly spots may appear skin coloured, red (keratosis pilaris rubra) or brown (hyperpigmented keratosis pilaris). They are not itchy or sore.Macules are flat, nonpalpable lesions usually < 10 mm in diameter.Examples include freckles, flat moles, tattoos, and port-wine stains, and the rashes of rickettsial infections, rubella, measles (can also have papules and plaques), and some allergic drug eruptions.Papules are elevated lesions usually < 10 mm in diameter that can be felt or palpated. Examples include nevi, warts, lichen planus, insect bites, seborrheic keratoses, actinic keratoses, some lesions of acne, and skin cancers. Plaques are palpable lesions > 10 mm in diameter that are elevated or depressed compared to the skin surface. Plaques may be flat topped or rounded. Lesions of psoriasis and granuloma annulare commonly form plaques.Nodules are firm papules or lesions that extend into the dermis or subcutaneous tissue. Examples include cysts, lipomas, and fibromas.Vesicles are small, clear, fluid-filled blisters < 10 mm in diameter. Vesicles are characteristic of herpes infections, acute allergic contact dermatitis, and some autoimmune blistering disorders (e.g., dermatitis herpetiformis).Bullae are clear fluid-filled blisters > 10 mm in diameter. These may be caused by burns, bites, irritant contact dermatitis or allergic contact dermatitis, and drug reactions. Classic autoimmune bullous diseases include pemphigus vulgaris and bullous pemphigoid. Bullae also may occur in inherited disorders of skin fragility.

Morphea, also known as localized scleroderma, is a disorder characterized by excessive collagen deposition leading to thickening of the dermis, subcutaneous tissues, or both. Morphea is classified into circumscribed, generalized, linear, and pansclerotic subtypes according to the clinical presentation and depth of tissue involvement. Unlike systemic sclerosis, morphea lacks features such as sclerodactyly, Raynaud phenomenon, nailfold capillary changes, telangiectasias, and progressive internal organ involvement. Morphea can present with extracutaneous manifestations, including fever, lymphadenopathy, arthralgias, fatigue, central nervous system involvement, as well as laboratory abnormalities, including eosinophilia, polyclonal hypergammaglobulinemia, and positive antinuclear antibodies.

Impetigo appears more commonly on the face than other exposed areas like the limbs. Its blisters are clustered and may have a fluid discharge.

Kaposi varicelliform eruption (KVE) is the name given to a distinct cutaneous eruption caused by herpes simplex virus (HSV) type 1, HSV-2, coxsackievirus A16, or vaccinia virus that infects a pre-existing dermatosis. Most commonly, it is caused by a disseminated HSV infection in patients with atopic dermatitis (AD) and, for this reason, is often referred to as eczema herpeticum (EH).Kaposi varicelliform eruption (KVE) is now known to occur in children of any age and in adults, however, most patients (56%) are aged 15-24 years.

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

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.

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.

“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.

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

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 or ulceration. 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), drugs like penicillin and sulphonamides, and malignancies like some leukemias and lymphomas.

Melanoma, a highly malignant tumour arising from melanocytes, is the most common life-threatening dermatological disease. Risk factors include UV radiation exposure, particularly in light-skinned individuals that are easily sunburned, increasing age, family history, and immunosuppression. Lesions that are suspicious for melanoma should be excised with complete margins. Radical excision is not routinely undertaken for diagnostic purposes and therefore if subsequent histopathological assessment determines that the lesion is a melanoma a re-excision of margins may be required.Margins of excision-Related to Breslow thicknessLesions 0-1mm thick – 1cmLesions 1-2mm thick – 1- 2cm (Depending upon site and pathological features)Lesions 2-4mm thick – 2-3 cm (Depending upon site and pathological features)Lesions >4 mm thick – 3cm

Mongolian spots, otherwise called congenital dermal melanocytosis, are pigmented birthmarks. They are usually located on the buttocks or back and although they’re usually present at birth, they may appear soon after. They are flat and have a blue-grey colour (bruise-like). They are benign and present no health risk.

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.

Certain infections and medications cause characteristic skin lesions, which are the result of hypersensitivity reactions to these agents. A skin rash characterized by the eruption of macules, papules, and target-like circular lesions is referred to as erythema multiforme. The target or iris lesions appear rounded with a red centre surrounded by a pale ring, which in turn is surrounded by a dark red outer ring. These are acute and self-limiting with a propensity for distal extremities. The most common infectious cause is the infection with herpes simplex virus 1 and 2 to a lesser extent. Other notable infectious causes of erythema multiforme include Mycoplasma pneumoniae, cytomegalovirus, HIV, hepatitis c virus, varicella zoster virus, adenovirus, and some fungal infections. Norovirus infection has not been implicated in the aetiology of erythema multiforme.

It is recommended that a woman wait one month after stopping isotretinoin before trying to become pregnant. Usually, isotretinoin is no longer found in a woman’s blood 4-5 days after the last dose and most of its by-products should be gone within 10 days after the last dose.

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.

A Mongolian spot can be present in new born babies which usually appears over the back and fades with time. There is nothing to worry about.

Capillary haemangiomas are one of the most common benign tumours of infancy. They are benign endothelial cell neoplasms that are typically absent at birth and characteristically have rapid growth in infancy with spontaneous involution later in life. This is in contrast to another known group of childhood vascular anomalies, vascular malformations. Vascular malformations, such as lymphangiomas and arteriovenous malformations, are present at birth and are characterized by very slow growth with persistence into adult life. The indications for treatment can be divided into systemic, ophthalmic, and dermatologic reasons. Systemic reasons for intervention include congestive heart failure, thrombocytopenia, haemolytic anaemia, and nasopharyngeal obstruction. Ophthalmic indications for intervention include occlusion of the visual axis, optic nerve compression, severe proptosis, and anisometropia. Dermatologic indications for intervention include maceration and erosion of the epidermis, infection, and cosmetic disfigurement.The first-line treatment of capillary haemangiomas is simple observation. Since most of these lesions regress on their own, there is no need to intervene unless one of the above criteria is met.

This patient is most likely suffering from hand, foot mouth disease which is caused by coxsackie virus A16. Its incubation period ranges from 5-7 days and only symptomatic treatment is required.

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.

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.

Café-au-lait spots is hyperpigmented lesions that vary in colour from light brown to dark brown, with borders that may be smooth or irregular. Causes include:
Neurofibromatosis type I
McCune–Albright syndrome
Legius syndrome
Tuberous sclerosis
Fanconi anaemia
Idiopathic
Ataxia-telangiectasia
Basal cell nevus syndrome
Benign congenital skin lesion
Bloom syndrome
Chediak-Higashi syndrome
Congenital nevus
Gaucher disease
Hunter syndrome
Maffucci syndrome
Multiple mucosal neuroma syndrome
Noonan syndrome
Pulmonary Stenosis
Silver–Russell syndrome
Watson syndrome
Wiskott–Aldrich syndrome

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).

Port-wine stains are a type of vascular birthmark caused by the abnormal development of capillaries in the skin. These pinkish-purplish discolorations present at birth and are associated with medical conditions such as Sturge-Weber syndrome, a neurocutaneous disorder involving the leptomeninges. Port wine stains are therefore associated with epilepsy, glaucoma or intellectual disability common in Sturge-Weber syndrome. Additional complications of Port wine stains include a loss of function if near the eye or mouth due to hypertrophy, or glaucoma if near the eyelid.

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.

Scabies is a dermatological condition caused by infestation of the Sarcoptes Scaibie. The tiny mite, often unseen by the naked human eye, is able to burrow into the stratum corneum where it lays its eggs, causing irritation and a rash related to the immune response against the mite and its eggs, saliva and faeces. On examination, the pathognomic small burrows are often seen on the skin along with small red papules and scratch marks| granulomatous nodules may also be seen especially in darker skin types. Other clinical subtypes such as bullous, and Norwegian (crusted) also exist. Common areas of infection include the hands, wrists, and the interdigital spaces. Infestation can also occur on the genital area, the buttocks, feet, ankles, flexor surfaces. First line treatment is with permethrin 5% dermal cream. It is important that all members of the household are also treated at the same time, and that contaminated bedding, clothes and furniture is adequately disinfected. Scabies is usually associated with overcrowded conditions.

The most probable cause for the patient’s presenting symptoms is Sarcoptes scabeii.Scabies:The boy in the scenario presents with a pruritic rash affecting the palms of the hands, especially in the web spaces between the fingers. Additionally, the fact that his sister is showing similar symptoms is an indication of its infectivity. The female Sarcoptes scabiei var hominis mite burrows into the webs of fingers and the sides of digits as seen in the child.This parasitic skin infestation presents typically with nocturnal itching. Other options:- Herpes simplex virus type 1 (HSV-1): This can affect this age group but would usually present with a vesicular perioral rash with associated erythema. – Human papillomavirus (HPV): Cutaneous human papillomavirus infection causes warts, which can form a dome and fleshy shaped lesions on the palms of the hands, but these are not usually itchy. Similar to the causative agent in the boy, they are contagious.- Poxvirus: These viruses cause molluscum contagiosum which presents as dome-shaped lesions anywhere on the body, rather than specifically in palms of hands or finger webs as seen in the boy. Poxviruses are also very infectious.- Staphylococcal infection: This causes impetigo, which presents with yellow discharge and underlying erythema. Impetigo is not usually itchy and can present on any part of the body, rather than the specific areas seen in the boy.

The most probable diagnosis for this patient’s symptoms is psoriasis. Psoriasis:Chronic plaque psoriasis is characterised by pinkish-red hyperkeratotic plaques, which occur mainly on extensor surfaces such as knees and elbows. The lower back, ears and scalp can also be involved. Koebner phenomenon: Psoriasis typically exhibits this phenomenon where new plaques of psoriasis occur particularly at sites of skin trauma. Diagnosis:Skin biopsy of psoriatic plaques reveals acanthosis and parakeratosis, reflecting increased skin turnover. Capillary dilatation within the dermis also occurs, surrounded by a mixed neutrophilic and lymphohistiocytic perivascular infiltrate.