📚 Question Bank

Hailey–Hailey disease has an intertriginous distribution.

Distribution pattern

Dermatomal / zosterifor m

Blaschkoid

Lymphangitic Sun-exposed

Sun-protected Acral Extensor

Flexor

Description

Unilateral and in the distribu tion of a single spinal afferen t nerve root

Following lines of skin cell m igration during embryogenesi s

Distribution of a lymph vesse l

Areas not covered by clothing (face, dorsal hands, V area of neck)

Areas covered by clothing

Distal locations (hands, feet, wrists, and ankles)

Dorsal extremities, overlying the extensor muscles, knees, or elbows

Flexor muscles of the extremi ties, antecubital and popliteal fossae

Examples Herpes zoster

Incontinentia pigmenti

CellulitisSporotrichosisSwim ming pool granuloma

PhotodermatitisSubacute cut aneous lupus erythematosus

ParapsoriasisMycosis fungoid es

Palmoplantar pustulosisChilb lains

PsoriasisDermatitis herpetifo rmis

Atopic dermatitis (childhood and adult phase)

Distribution pattern Description Examples

Intertriginous

Skin folds, where two skin su rfaces are in contact (axilla, i nguinal folds, inner thighs, in framammary)

CandidiasisHailey-Hailey dis ease

The given image shows serpiginous or serpent-like skin lesions, which are characteristically seen in cutaneous larva migrans or ground itch.

It is caused by the larvae of various hookworm or Ancylostoma species. The parasite is acquired from direct skin contact with soil contaminated by dog or cat feces. It is common following travel to endemic or tropical areas and symptoms develop within the first 2 weeks.

The site of entry is marked by an inflamed papule, often located between the toes. Serpentine or linear single-track lines later appear as the larvae migrate through the epidermis. The lesions can enlarge as much as 1 to 2 cm per day.

The first-line treatment is oral ivermectin at 200 μg/kg. Oral albendazole is an alternative treatment.

Note: Larva currens is caused by the migrating larva of Strongyloides stercoralis. It also produces serpiginous lesions and can be differentiated by the faster rate of progression and haphazard distribution of lesions.

The image below shows serpiginous larval tracks over the skin.

The yellowish greasy scales on the scalp of an infant are characteristic of seborrheic dermatitis.

Seborrheic dermatitis is a common, inflammatory skin condition that causes the formation of flaky, white to yellowish greasy scales on oily areas such as the scalp, forehead, nose, or inside the ear. It is known as cradle cap when it affects the scalp of infants, as shown in the image below:

Other options:

Option A: Impetigo presents with shallow bullae. When ruptured, they result in erosions and discharge that forms honey-colored crusting.

Option C: Atopic dermatitis presents in infants as an itchy erythematous rash that affects the face and flexural areas such as elbows. The given image shows atopic dermatitis on the abdomen and thigh of an infant:

Option D: Tinea capitis is ringworm of the scalp. It is uncommon in infants. It is common in older children and presents as patches of alopecia associated with scaling or black dots (swollen hair shafts).

The given image shows severe tinea capitis infection with follicles discharging pus, this clinical variant is known as kerion:

Loss of temperature sensation is not associated with poikiloderma. Poikiloderma is a special skin lesion with a triad of features:

• Cutaneous pigmentation (both hypopigmentation and hyperpigmentation)
• Skin atrophy
• Telangiectasia

It may be congenital or acquired. It is associated with mycosis fungoides, dermatomyositis, xeroderma pigmentosum, etc.

In patch testing, the patch is removed after 48 hours to examine the site of reaction.

Patch testing is a test to detect sensitivity to a specific allergen. A battery of suspected allergens is applied to the patient’s back under occlusive dressings or patches. It is allowed to remain in contact with the skin for 48 hours.

• 48 hours: Patch removal for initial reading to detect delayed hypersensitivity reaction.
• 72-96 hours: Final reading done for confirmation.

Note: Since the question is regarding the timing of patch removal and not regarding the final diagnosis, 48 hours is the answer.

Ivory or milky-white fluorescence on Wood's lamp examination is seen in vitiligo.

In vitiligo, there is less or no epidermal melanin in the affected patches. As the normal function of melanin is to absorb light, the vitiligo-affected patches cannot block the light emitted from deeper layers of the skin. They appear as bluish, milky, or ivory white patches with sharp margins. Woods lamp is hence helpful in the diagnosis of vitiligo, especially in fair-skinned people in whom lesions may not be obvious to the naked eye.

The following image shows milky-white fluorescence under a Wood's lamp.

Coral pink fluorescence on Wood's lamp examination is characteristic of erythrasma.

Erythrasma is a skin infection caused by Corynebacterium minutissimum. It is common in diabetics and immunodeficient patients and is associated with obesity, sweating and poor hygiene.

Coral pink fluorescence is due to the production of coproporphyrin III by the bacterium.

Hansen's disease is diagnosed by slit skin smear for acid-fast bacilli using the modified Ziehl-Neelsen technique.

Some important findings on Tzanck smear are as follows:

Tzanck Smear findings Acantholytic cells

Degenerated necrosed kerati nocytes

Dyskeratotic acantholytic cell s

Multinucleated giant cells

Henderson-Patterson bodies Leishman-Donovan bodies Clusters of basaloid cells

Disease

Pemphigus, Hailey-Hailey dis ease

Toxic epidermal necrolysis

Staphylococcal scalded skin s yndrome, Bullous impetigo

Herpes simplex virus 1 and 2, Herpes zoster

Molluscum contagiosum Leishmaniasis

Basal cell carcinoma

The test depicted in the given image is diascopy.

It involves pressing a glass slide or a stiff, clear, colorless piece of plastic onto the skin to cause blanching by compressing blood out of small vessels. This allows other colors to be evaluated.

Some uses of diascopy are as follows:

• Apple jelly nodules - Yellow-brown lesions seen in lupus vulgaris and sarcoidosis.
• Spider naevi - Compression of radiating arterioles is noted.
• Differentiation of erythema (disappears) and purpura (remains unaltered).
• The image given below shows apple-jelly nodules on diascopy.

10 neutral buffered formalin is the most widely used fixative for routine diagnostic microscopy of paraffin-embedded tissue samples.

Skin biopsies are indicated in various conditions like epidermal or dermal neoplasms as well as blistering disorders for immunofluorescence. Michel's medium is used as a transport medium.

Various techniques of skin biopsy are available based on the lesions to be biopsied:

Technique Excision

Incision biopsy(wedg e)

Punch biopsy (3-6 m m)

Curettage

Shave biopsy

Snip

Application

For removal of a single, small lesion. An elliptical or fusifo rmshaped area of skin is rem oved

A part of a large lesion is rem oved, with some normal peri- lesional skinfor comparison

Useful for accurate sampling of limited tissue

For hyperkeratotic lesions lik e seborrhoeickeratoses, viral warts, basal cell carcinomas. It is usually accompanied by cautery

For protuberant lesions on th e face like benign intraderma l naevi

For skin tags

The microscopic picture described in this clinical scenario is called spaghetti and meatball appearance. It is diagnostic of pityriasis versicolor or tinea versicolor.

Skin scrapings from the lesions are mounted in 10-30 potassium hydroxide. A

higher percentage of KOH solution speeds up the process. It is then observed under fluorescence microscopy using a fluorescent brightener like Calcofluor white or Blankophor which specifically stains polysaccharides in the fungal cell wall.

The hyphae and spherical Malassezia yeasts are called spaghetti and meatballs or bananas and grapes appearance as shown below.

The given image shows a photo-patch test. Skin reaction is seen on the uncovered side that is exposed to UV rays.

Photo-patch test is useful in the diagnosis of photosensitive rashes and photoallergic contact dermatitis that are typically localized to the sun-exposed areas of the skin.

UV light is used at a dose sufficient to trigger the photoallergic response, without causing a false positive phototoxic reaction. It is performed like a conventional patch test, except two sets of allergens are applied over the back. The control set of allergens and the rest of the skin

are covered with an opaque material. The patient is positioned 15 cm from a UV lamp and the test site is irradiated with UV light.

This test is best read after 48 hours. In the case of a positive test indicating photoallergy, the exposed side shows a reaction.

Amorolfine is a morpholine that is available as a 5 nail lacquer. It is used in the treatment of onychomycosis.

Options B and D: Oxiconazole and tioconazole are classified as imidazoles Option C: Ciclopirox olamine is a hydroxypyridone compound.

The given image shows ring-shaped lesions with central clearing, which are characteristic of annular lesions.

In annular lesions, only the edges are active and appear raised, or in a different color. They are seen in tinea corporis, granuloma annulare, borderline leprosy, and psoriasis.

This image shows silvery or mica scales on the extensor aspect of the elbow, which is indicative of psoriasis.

Scales are flakes of stratum corneum that are characteristic of processes involving parakeratosis. The silvery colour is due to reflection of light at many air–keratin interfaces and can be altered by wetting the skin.

Purpura and vesicles are primary skin lesions.

Comedones are the specific lesions of acne vulgaris.

Acne is a chronic inflammatory disease of the pilosebaceous unit. Comedonal lesions are the earliest lesions of acne. They represent the keratin plugs of the pilosebaceous duct.

When the keratin plug is inside the follicle, it is called a closed comedone (whitehead).

When the keratin plug is exposed to the environment, it gets oxidized by the air and turns black which is known as open comedone (blackhead).

The age of the patient and the presence of papules and pustules with an erythematous base on the face are suggestive of acne vulgaris.

It is commonly seen in teenagers and young adults. The condition can vary from very mild comedonal acne to severe aggressive pustular acne. These eventually may lead to scarring due to sinus formation.

Option A: Acne rosacea or Rosacea is predominantly a disease with onset in middleaged adults

(30–50 years old) and involves the convexities of the face.

Option C: Eczema presents more over the flexures and extremities from early adulthood. Features of pruritus and excoriations are predominant.

Option D: Tinea faciei is a fungal infection of the face and presents with a scaly lesion.

Seborrhoea is a constituent of SAHA syndrome, not SAPHO syndrome. SAPHO syndrome consists of:

• Synovitis
• Acne
• Pustulosis
• Hyperostosis
• Osteitis

A teenager presenting with papulopustular lesions on the face and the presence of comedones is most likely suffering from acne vulgaris. Oily skin due to excessive sebum production is one of the causative factors of acne, but oily food is not directly implicated

Acne results from the combination of:

• Increased sebaceous gland activity under the influence of androgens - oily skin
• Abnormal follicular differentiation with increased keratinization- hypercornification of duct due to increased IL-1
• Microbial hypercolonization of the follicular canal leading to its inflammation.

The presence of multiple nodulocystic lesions implies that this is a case of severe

acne. Isotretinoin is the first-line drug for the treatment of severe acne (nodular acne and acne conglobata).

Systemic retinoids are highly teratogenic and are absolutely contraindicated in pregnant women, those planning to become pregnant, or breastfeeding mothers. Two negative pregnancy tests (on

separate occasions) are required for females of childbearing age before starting acitretin or isotretinoin.

Baseline evaluation of serum lipids, transaminases, and complete blood counts should be done before starting any systemic retinoids. These values should be checked monthly for the first 3–6 months and once every 3 months thereafter. Monthly pregnancy tests should be done while on the drug.

Note: Female patients should avoid conception for 3 years after discontinuing acitretin treatment for cutaneous psoriasis.

Oral isotretinoin, an oral retinoid is indicated for the treatment of recalcitrant acne.

Recalcitrant acne is poorly responsive acne, less than 50 improvement after 6 months of therapy with combined oral and topical antibiotics.

Liver function tests (LFT) must be monitored during retinoid therapy as it can lead to variation in LFT by causing drug-induced liver injury.

Side effects of retinoids:

• Cheilitis/dryness of lips (most common)
• Deranged liver function tests
• Hypertriglyceridemia
• Teratogenicity - contraception is required until 1 month of stoppage of isotretinoin.

Note: Female patients should avoid conception for 3 years after discontinuing acitretin treatment to prevent retinoid-induced embryopathy.

Moderate acne with irregular menses are best treated with OCPs.

Giving OCP will increase sex hormone-binding globulin (SHBG) and hence reduce free androgens which play a major role in the pathogenesis of acne. In addition, OCPs also help in regularising the menses.

The image shows typical erythematous papules and nodules along with few whiteheads, suggestive of acne vulgaris.

Other options:

Option B: Acne rosacea is a disorder that appears mainly in people within 30 to 50 years of age. The lesions are mainly present on the convexities of the face but don't lead to central crusting or scarring. It is followed by triggering factors such as sunlight exposure, emotional disturbances, spicy food, alcohol, etc.,

Given below is an image showing acne rosacea:

Option C: Seborrheic dermatitis is a chronic inflammatory skin condition which presents with erythematous patches with superficial scaling, affecting areas with a high density of sebaceous glands- scalp, face, central chest, and anogenital areas.

Option D: Milia are small cysts formed around the pilosebaceous follicles usually seen over nose, cheek, forehead of neonates. Pearly opalescent white epidermal inclusion cysts. Resolve

spontaneously without scarring.