The cause of Vitiligo is typically unknown. It is believed to be due to genetic susceptibility that is triggered by an environmental factor such that an autoimmune disease occurs. This results in the destruction of skin pigment cells. Risk factors include a family history of the condition or other autoimmune diseases, such as hyperthyroidism, alopecia areata, and pernicious anaemia. Vitiligo is classified into two main types: segmental and non-segmental. Most cases are non-segmental meaning they affect both sides and typically get worse with time. The prevalence of vitiligo is 0.5-1% of populations worldwide. Typical sites include backs of hands, wrists, knees, neck and around body orifices. The Koebner phenomenon refers to skin lesions appearing on lines of trauma. This occurs in vitiligo secondary to scratching.

If steroid is applied first, applying an emollient after could spread it from where it had been applied. If steroid is applied immediately after the emollient then it cannot be absorbed, this is why there should be a time interval of around thirty minutes between these two treatments in order for them to be effective.

Melanocytic naevi are skin tumours produced by melanocytes. They usually present in childhood but increase during puberty. The mnemonic A-B-C-D, is used by institutions to assess for suspicion of malignancy. The letters stand for asymmetry, border, colour, and diameter. If a mole starts changing in size, colour, shape or, especially, if the border of a mole develops ragged edges or becomes larger than a pencil eraser, it would be an appropriate time to consult with a physician. Other warning signs include if it begins to crust over, bleed, itch, or become inflamed.

Squamous-cell skin cancer usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months and it is more likely to spread to distant areas than basal cell cancer vie the lymphatics. The greatest risk factor is high total exposure to ultraviolet radiation from the Sun. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen’s disease, arsenic exposure, radiation therapy, poor immune system function, previous basal cell carcinoma, and HPV infection. While prognosis is usually good, if distant spread occurs five-year survival is ,34%

Scabies is an infection caused by a microscopic mite known as Sarcoptes scabies. The chief presenting complaint is itching especially in skin folds and mostly during night. It spreads from one person to another through skin contact, and therefore it is more prevalent in crowded areas like hospitals, hostels and even at homes where people live in close contact with each other. Treatment options include benzyl benzoate, ivermectin, sulphur and permethrin.

Psoriasis is a long-lasting autoimmune disease characterized by patches of skin typically red, dry, itchy, and scaly. Psoriasis can affect the nails and produces a variety of changes in the appearance of finger and toe nails including pitting and onycholysis. Nail psoriasis occurs in 40-45% of people with psoriasis affecting the skin and has a lifetime incidence of 80-90% in those with psoriatic arthritis. Psoriasis is mediated by type 1 helper T cells which are involved in the cell mediated response.

Sunlight, especially its ultraviolet radiation component, can cause increased or additional types of damage in predisposed individuals, such as those taking certain phototoxic drugs, or those with certain conditions associated with photosensitivity, including:
– Psoriasis
– Atopic eczema
– Erythema multiforme
– Seborrheic dermatitis
– Autoimmune bullous diseases (immunobullous diseases)
– Mycosis fungoides
– Smith-Lemli-Opitz syndrome
– Porphyria cutanea tarda
Also, many conditions are aggravated by strong light, including:
– Systemic lupus erythematosus
– Sjögren’s syndrome
– Sinear Usher syndrome
– Rosacea
– Dermatomyositis
– Darier’s disease
– Kindler-Weary syndrome
Acute intermittent porphyria (AIP) belongs to the group inborn errors of metabolism and most patients with AIP are not light sensitive.

Yellow nail syndrome is a very rare medical syndrome that includes pleural effusions, lymphedema (due to under development of the lymphatic vessels) and yellow dystrophic nails. Approximately 40% will also have bronchiectasis. It is also associated with chronic sinusitis and persistent coughing and it usually affects adults.

Clubbing of the fingers can be present in many clinical conditions like CLD, bronchiectasis, lung abscess, Ulcerative colitis and Crohn’s Disease. Koilonychia or spoon shaped nails are a typical finding in iron deficiency anaemia. Splinter haemorrhages are pin point haemorrhages found in infective endocarditis and secondary to trauma. Yellow nails are present in pulmonary and renal diseases.

The skin lesion is most probably eczema. It is common among atopic people. Asthma is a common association.

Favus is a fungal infection of the scalp, resulting in the formation of a yellowish crusted plaque over the scalp and leads to scar formation with alopecia. Tinea capitus is a fungal infection of the scalp resulting in scaling and non scarring hair loss. Folliculitis presents with multiple perifollicular papules which can be caused by both bacteria and fungi. Cradle cap usually affects infants where the whole scalp is involved. It can lead to hair loss and responds to topical antifungals and keratolytics.

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.

The chief presentation in Leishmaniasis is a non healing, ulcerated, painless and non pruritic plaque, which does not respond to oral antibiotics. It can be classified into cutaneous and visceral forms and is caused by the sand fly. It is more prevalent in the hilly areas. Fusobacterium causes a tropical ulcer which is painful and shallow, while Troanasomiasis causes sleeping sickness.

The following are conditions commonly associated with pyoderma gangrenosum:
Inflammatory bowel disease:
– Ulcerative colitis
– Crohn’s disease
Arthritides:
– Rheumatoid arthritis
– Seronegative arthritis
Haematological disease:
– Myelocytic leukaemia[8]
– Hairy cell leukaemia
– Myelofibrosis
– Myeloid metaplasia
– Monoclonal gammopathy
Autoinflammatory disease:
– Pyogenic sterile arthritis, pyoderma gangrenosum, and acne syndrome (PAPA syndrome)
– Granulomatosis with polyangiitis

Koilonychia, known as spoon nails, is a condition of the nails bending inwards, taking the shape of a spoon. This is a strong indication of iron-deficiency anaemia (IDA). The rest of the patient’s symptoms further indicate IDA.

Riboflavin, vitamin B2, is a water-soluble and heat-stable vitamin that the body uses to metabolize fats, protein, and carbohydrates into glucose for energy. Riboflavin deficiency can cause fatigue, swollen throat, blurred vision, and depression. It can affect the skin by causing skin cracks, itching, and dermatitis around the mouth. Hyperaemia and oedema around throat, liver degeneration, and hair loss can also occur along with reproductive issues. Usually, people with riboflavin deficiency also have deficiencies of other nutrients. In most cases, riboflavin deficiency can be reversed unless it has caused anatomical changes such as cataracts.

An escharotomy is a surgical procedure used to treat full-thickness (third-degree) circumferential burns. In full-thickness burns, both the epidermis and the dermis are destroyed along with sensory nerves in the dermis. The tough leathery tissue remaining after a full-thickness burn has been termed eschar.

Squamous cell carcinoma like other skin cancers mostly arise on photo exposed sites. A patient usually presents with a history of a non healing lesion or wound. Confirmatory diagnosis requires a skin biopsy and histopathological screening. It is rarely metastatic and treatment of choice is surgical excision.

Diabetic dermadromes constitute a group of cutaneous conditions commonly seen in people with diabetes with longstanding disease. Conditions included in this group are:
– Acral dry gangrene
– Carotenosis
– Diabetic dermopathy
– Diabetic bulla
– Diabetic cheiroarthropathy
– Malum perforans
– Necrobiosis lipoidica
– Limited joint mobility
– Scleroderma
– Waxy skin is observed in roughly 50%. Sweet’s syndrome is also known as acute febrile neutrophilic dermatosis has a strong association with acute myeloid leukaemia. It is not associated with diabetes mellitus.

Melanoma is more common in men than women. Reasons for the disease includes: UV light and genetic predisposition or mutations. Diagnosis is by biopsy and analysis of any skin lesion that has signs of being potentially cancerous.
Early warning signs of melanoma ABCDE:
Asymmetry
Borders (irregular with edges and corners)
Colour (variegated)
Diameter (greater than 6 mm)
Evolving over time

Features that affect prognosis are tumour thickness in millimetres (Breslow’s depth – the deeper the Breslow thickness the poorer the prognosis.), depth related to skin structures (Clark level – the level of invasion through the dermis), type of melanoma, presence of ulceration, presence of lymphatic/perineural invasion, presence of tumour-infiltrating lymphocytes (if present, prognosis is better), location of lesion, presence of satellite lesions, and presence of regional or distant metastasis. Malignant melanoma tends to grow radially before entering a vertical growth phase. The diameter it reaches has not been found to be a prognostic factor.

Dermatomyositis is a long-term inflammatory disorder which affects muscles. Its symptoms are generally a skin rash and worsening muscle weakness in the proximal muscles (for example, the shoulders and thighs) over time. These may occur suddenly or develop over months. Other symptoms may include weight loss, fever, lung inflammation, or light sensitivity. Complications may include calcium deposits in muscles or skin.
The skin rash may manifest as aheliotrope (a purplish color) or lilac, but may also be red. It can occur around the eyes along with swelling, as well as the upper chest or back ( shawl sign) or V-sign above the breasts and may also occur on the face, upper arms, thighs, or hands. Another form the rash takes is called Gottron’s sign which are red or violet, sometimes scaly, slightly raised papules that erupt on any of the finger joints (the metacarpophalangeal joints or the interphalangeal joints)

Infective causes of hair loss include:
Dissecting cellulitis
Fungal infections (such as tinea capitis)
Folliculitis
Secondary syphilis
Demodex folliculorum
Lupus erythematosus (hair loss may be permanent due to scarring of the hair follicles).
Psoriasis and seborrheic dermatitis commonly involve the scalp but do not produce hair loss.

Onycholysis is the separation of the distal edge of the nail from the vascular nailbed causing whiteness of the free edge. Causes include:
– Idiopathic
– Trauma, excessive manicuring
– Infection: especially fungal
– Skin disease: psoriasis, dermatitis
– Impaired peripheral circulation e.g. Raynaud’s
– Systemic disease: hyper/hypothyroidism, reactive arthritis, porphyria cutanea tarda
– Sometimes a reaction to detergents (e.g. washing dishes with bare hands, using detergent-based shampoos or soaps).
– Patients with hepatocellular dysfunction may develop hair-thinning or hair loss and nail changes such as clubbing, leukonychia (whitening), or onycholysis.

Melanocytic nevi are benign neoplasms or hamartomas composed of melanocytes. Melanocytes are derived from the neural crest and migrate during embryogenesis to selected ectodermal sites (primarily the skin and the CNS), but also to the eyes and the ears.
They tend to appear during early childhood and during the first 30 years of life. They may change slowly, becoming raised, changing color or gradually fading.. Pregnancy can increase the number of naevi as well as the degree of hyperpigmentation.
They may become malignant and this should be suspected if the naevus increases in size, develops an irregular surface or becomes darker, itches or bleeds.

Urticaria is a group of disorders that share a distinct skin reaction pattern, namely the occurrence of itchy wheals anywhere on the skin. Wheals are short-lived elevated erythematous lesions ranging from a few millimetres to several centimetres in diameter and can become confluent. The itching can be prickling or burning and is usually worse in the evening or night time. Triggering of urticaria by infections has been discussed for many years but the exact role and pathogenesis of mast cell activation by infectious processes is unclear.

Mild cases are often not treated at all, or are simply covered up with normal cosmetics and avoiding sun exposure. Therapy for the treatment of rosacea is not curative, and is best measured in terms of reduction in the amount of facial redness and inflammatory lesions. The two primary modalities of rosacea treatment are topical and oral antibiotic agents (including metronidazole and tetracyclines). Laser therapy may be appropriate for patients with prominent telangiectasia.

Arterial ischemia ulcers present with many of the symptoms observed in this patient: ulcer on the lower extremities, pain, swelling, yellow sores, a punched-out appearance, the foot turning red when dangling from a bed. Smoking a lot is also known to be a causative factor here. This type of ulcer develops due to damage to the arteries caused by a lack of blood flow to the tissue – they are also deep wounds. Venous ischemic ulcers usually form in the knee or inner ankle area as opposed to the foot.

Contact dermatitis is a red, itchy rash caused by direct contact with a substance or an allergic reaction to it. The entry of allergen into the epidermis or dermis causes a localized allergic reaction. Local mast-cell activation in the skin leads immediately to a local increase in vascular permeability, which causes extravasation of fluid and swelling. Histamine released by mast cells activated by allergen in the skin causes large, itchy, red swellings of the skin.

Tinea manum is a superficial fungal infection of the hands characterised by dry scaly rash and also involves the interdigital spaces of the hands. Tinea pedis is a fungal infection of feet, whereas onychomycosis represents a fungal infection of the nails, characterised by nail dystrophy, hyperkeratosis. Kerion is the name given to secondarily infected tinea capitis leading to a soft boggy swelling over the scalp. Psoriasis presents as silvery scales over the extensors of the body and it may involve the nails, scalp and joints.