📚 Question Bank

This clinical scenario with a history of exposure to tuberculosis is suggestive of lupus vulgaris, which often presents as atrophic warty plaques. It is a paucibacillary lesion.

It occurs in previously sensitized hosts with good immunity. On histology, granulomas with scanty or absent caseation are seen.

It is the most common cutaneous tuberculosis in India. In India, it commonly occurs over the buttocks or the trunk, whereas, in Europe, it is common over the head and neck.

The lesions occur in the form of plaques with serpiginous edges or mutilating ulcers. They heal with central scarring.

The given image shows an annular plaque with central scarring points to lupus vulgaris, which is treated using anti-tubercular drugs.

It is the most common cutaneous tuberculosis in India. The characteristic lesions are annular, infiltrated plaques with serpiginous edges, central atrophy and scarring and are commonly seen on face, buttocks and extremities.

On diascopy, apple jelly nodules are seen.

Histologically, tubercles are seen in the superficial dermis showing scanty or absent central caseation with surrounding epithelioid histiocytes and giant cells.

Other differential diagnoses for annular plaque include:

• Tinea corporis shows central clearing, peripherally raised scaly margins and presents with an itch.
• Cutaneous leishmaniasis lesions have central crusting and are seen on the face in patients from areas of high leishmaniasis prevalence.

The given image shows non-healing sinuses in the cervical region, which are a feature of scrofuloderma. It is a multibacillary manifestation of cutaneous tuberculosis.

It is the most common form of cutaneous tuberculosis worldwide. However, in India, lupus vulgaris is the most common type in adults.

It results from contiguous spread to the skin from an underlying tuberculous focus. The lesions evolve as follows:

• Begins as asymptomatic, bluish-red, subcutaneous swellings (persist for months)
• Break down to form undermined ulcers
• Proliferation of granulation tissue in ulcers forms fungating masses
• Numerous fistulae may occur, which can form draining sinuses onto the skin.

Histology shows marked caseating necrosis, in which there are usually numerous bacteria.

Spontaneous healing can occur, but the course is very protracted and leaves typical, cordlike scars.

Antituberculous therapy should be commenced promptly.

Tuberculosis verrucosa cutis is a form of post-primary tuberculosis that occurs in previously sensitized people with good immunity.

It is also called:

• Warty tuberculosis
• Anatomist’s warts
• Prosector’s warts
• Verruca necrogenica

It is caused by exogenous inoculation of M. tuberculosis into the skin through open wounds or abrasions. Due to the strong immune response, the lesion is paucibacillary. Histology shows hyperkeratosis with no granulomas.

The lesions are typically asymptomatic and start as a small, indurated, warty papule which by gradual extension, form a verrucous plaque, as shown below. Irregular extension at the edges leads to a serpiginous outline with fingerlike projections.

Management: Antitubercular therapy

Non-caseating epithelioid granulomas surrounding sweat glands and hair follicles are seen in lichen scrofulosorum.

Lichen scrofulosorum is a tuberculid. It is a cutaneous hypersensitivity reaction to the hematogenous spread of M.tuberculosis antigens.

It presents as a lichenoid eruption of tiny papules occurring predominantly in children and adolescents with active tuberculosis.

The tuberculin test is usually strongly positive.

With specific ATT, the lesions usually clear within 4 weeks without scarring.

Option B: Miliary tuberculosis refers to disseminated internal tuberculosis. Histology shows caseating tuberculous granulomas with multiple acidfast bacilli.

Option C: Papulonecrotic type of tuberculid occurs due to thrombosis and destruction of small dermal vessels as a result of vasculitis.

Option D: Lupus vulgaris, on histology, shows tuberculous granulomas with scanty or absent caseation in the superficial dermis. There is no specific involvement around the hair follicles and sweat glands.

Erythema induratum of Bazin is a hypersensitivity reaction due to tuberculosis. It is the most common form of tuberculid. It mostly affects middle-aged females.

The pathology is granulomatous vasculitis and panniculitis. It classically presents as crops of small, tender, erythematous nodules or plaques on the calves, which may ulcerate.

The following image shows plaques over the calf region:

The given image shows a fish tank granuloma or swimming pool granuloma, which is caused by Mycobacterium marinum.

M. marinum enters the body through abrasions or minor cuts on the skin, which come into contact with contaminated fresh or saltwater.

Skin lesions develop after an average incubation period of 2–3 weeks. The most common presentation is a nodule on the hand or arm that spreads in a sporotrichoid fashion, with a succession of nodules along the lymphatics, as shown below. Ulcers and abscesses may occur in immunocompromised patients.

The given clinical scenario is that of a Buruli ulcer, which is caused by Mycobacterium ulcerans.

It is the third most common mycobacterial skin infection in immunocompetent people. It is endemic to Africa and Australia, where it affects children and elderly people. It starts as a nodule or papule which progresses further to form an extensive, necrotic ulcer, exposing muscle and tendon. Most lesions occur on the lower extremities. Healing is slow.

The above image shows Gram-positive cocci in clusters, suggestive of staphylococcus. It causes pemphigus neonatorum or bullous impetigo of the newborn.

Option A: Pyoderma gangrenosum is a neutrophilic dermatosis characterized by chronic, recurrent, very painful ulcers with undermined borders usually found on the lower limbs. It is usually associated with inflammatory bowel disease.

Option C: Impetigo herpetiformis is severe pustular psoriasis in pregnancy.

Option D: Ecthyma contagiosum is a contagious pustular dermatitis and a viral zoonotic disease caused by the parapox virus.

Beta-hemolysis on blood agar and the catalase-negative test is suggestive of Streptococcus pyogenes. It causes scarlet fever, erythema nodosum and can be a provocative factor for Kawasaki disease.

Carbuncle is caused by Staphylococcus aureus.

The above image showing a bullous lesion which has ruptured is suggestive of bullous impetigo. It is caused by Staphylococcus aureus.

The above scenario is suggestive of non-bullous impetigo.

It starts as very flaccid blisters, which soon rupture, creating erosions that are covered by characteristic golden yellow or honey-colored crusts.

The above scenario is suggestive of streptococcal impetigo. Rheumatic fever is a complication of streptococcal pharyngitis, not impetigo.

The complications of streptococcal impetigo include:

• Scarlet fever
• Erythema multiforme
• Post-streptococcal glomerulonephritis.
• Cellulitis

Infective complications are uncommon in the absence of systemic disease or malnutrition.

The above image is suggestive of staphylococcal scalded skin syndrome or SSSS. Exfoliative toxin (ETA and ETB) is produced by the cocci which targets the cell adhesion protein desmoglein 1 (DG1) resulting in the separation of intraepidermal keratinocytes.

A widespread erythematous eruption is seen more in flexures leading to blister formation (Nikolsky positive) and ultimately painful raw areas. Dislodgement of the intact superficial epidermis by a shearing force, indicating a plane of cleavage is called the Nikolsky sign.

Children (lt;6 years) and neonates are most commonly affected by the generalized form of SSSS, rarely adults may be affected. In children, SSSS is known as Ritter disease. Staphylococcal scalded skin syndrome usually settles within a few weeks when treated with appropriate systemic antibiotics.

The image shows several bullae filled with turbid pus-like fluid indicating a diagnosis of bullous impetigo. Regional lymphadenitis is rare in bullous impetigo.

Impetigo is a contagious, superficial pyogenic infection of the skin. The face, especially around the nose, mouth, and limbs, is most commonly affected, but lesions may occur anywhere.

Superficial intraepidermal bullae are formed as desmoglein-1 is targetted by the exfoliative toxins produced by S. aureus. After the bullae rupture, they leave behind varnish crust. Central healing and peripheral extension may give rise to circinate lesions which are eroded.

Treatment involves topical fucidin or mupirocin, retapamulin in resistant cases. Systemically therapy with flucloxacillin and erythromycin may be given.

Erythrasma is an infection of the skin caused by Corynebacterium minutissimum.

Lesions are sharp hyperpigmented patches that may be symptomless or show mild discomfort and itching. It usually affects the axilla, groin, inter-gluteal, and submammary regions.

Coral pink/red fluorescence due to coproporphyrin III under Wood's lamp indicates erythrasma.

The above scenario is suggestive of trichomycosis axillaris which is caused by Corynebacterium tenuis.

It is a superficial infection of axillary and pubic hairs with the formation of yellow, black, or red nodular concretions on the hair shaft. The axillary sweat may be yellow, black, or red according to the color of the concretions, and the clothing may be stained.

The condition is usually asymptomatic and the patient is often unaware of its presence. The use of an effective antiperspirant such as aluminum chloride is a rapid means of therapy.

The image below shows trichomycosis axillaris in the axilla with a close-up view of nodules on the hair shaft.

The above scenario is suggestive of ecthyma which is characterized by thick adherent crusts over the pustular lesions.

It is a pyogenic infection of the skin characterized by the formation of adherent crusts, beneath which ulceration occurs. It most commonly results from mixed infection of group A streptococci gt; staphylococci and causes a deeper infection than impetigo. The buttocks, thighs, and legs are most commonly affected.

Risk factors include:

• Extremes of age
• Immunocompromised
• Diabetes
• Poor hygiene.

Treatment: Topical fucidin, topical mupirocin, and systemic cloxacillin.

Option A: Botryomycosis presents as multiple indurated draining sinuses mimicking actinomycosis.

Option B: In erysipelas, well-defined raised margin erythematous lesions are seen.

Option C: Carbuncle is a deep-seated cutaneous infection around a group of hair follicles with sieve-like multiple openings discharging pus.

The above image showing necrotic ulcers in an immunocompromised patient is suggestive of ecthyma gangrenosum. It is caused by Pseudomonas aeruginosa.

The characteristic lesions of ecthyma gangrenosum are hemorrhagic pustules that evolve into a necrotic (black) ulcer. It commonly occurs in the axillae, perineum, buttocks.

The above image showing multiple skin abscesses with mucopurulent discharge through multiple sinuses which does not show filamentous organisms on staining with Gomori methenamine silver (GMS negative) is suggestive of botryomycosis. It is caused by staphylococci.

Botryomycosis is a misnomer. It is a bacterial infection caused usually by staphylococcus. It is a chronic granulomatous reaction to bacterial infection, containing granules resembling the sulfur granules of actinomycosis.

Etiological agents include:

• Staphylococcus aureus (most common)
• Pseudomonas
• Escherichia coli
• Proteus
• Streptococcus.

Most lesions are on the limbs, but other sites including the perianal region and the face are affected.

Treatment is with antibiotics against S.aureus - flucloxacillin or erythromycin.

The above scenario depicts acute suppurative infection of the nail beds and folds which is called acute paronychia. It is most commonly caused by Staphylococcus aureus.

Acute paronychia is infection of the nail fold are represented by inflammation, swelling and abscess formation.

It presents as tender, purulent swellings around the nail.

Diagnosis is clinical and a cover of systemic antibiotics may be needed for deep infections. Treatment of pyogenic paronychia:

• Protection against trauma
• Keep affected fingernails dry.
• Abscesses - incised and drained. (abscess is often opened by pushing the nail fold away from the nail plate)
• Antibiotics- Semisynthetic penicillin/ cephalosporin with excellent anti-staphylococcal orally.
• Complications of acute paronychia may include osteitis and amputation.

The infant presents with an infection focus (otitis media) that is followed by generalized peeling of the skin and toxic state of the baby without any mucosal involvement which is suggestive

of staphylococcal scalded skin syndrome.

Age

Mucosal involvem ent

Nikolsky sign

Targetoid lesions Histopathology

Staphylococcal scalded skin s yndrome

Infants and children under a ge of 6

No Positive

Absent

Acantholytic cells with subco rneal or subgranular blister

Stevens-Johnson syndrome/ Toxic epidermal necrolysis

Adults Yes

Pseudo-Nikolsky sign Positiv e

Present

Necrotic keratinocytesDermo

-epidermal separation

The above clinical scenario is suggestive of sycosis barbae which is caused by Staphylococcus aureus.

Sycosis is a subacute or chronic infection involving the whole depth of the follicle. It is a disease of the beard area. The essential lesion is an oedematous erythematous follicular papule or pustule centered on a hair. The individual papules may coalesce to produce the appearance of a ripe fig. It is a non-scarring pyogenic infection.

If the follicles are destroyed with evident scarring, the term lupoid sycosis is used.

Tinea barbae/tinea sycosis is a dermatophyte infection caused by Trichophyton tonsurans, the upper lip is spared.

Herpetic sycosis is caused by the herpes simplex virus.

In erysepeloid, human infection is contracted by direct contact with animals.

Erysipeloid is an acute infection with Erysipelothrix rusiopathiae, a Grampositive bacillus living mainly on dead animal matter. It causes diseases in many animals, especially in pigs. It usually affects butchers, cooks, fishermen, farmers, and veterinary surgeons.

About 3 days after inoculation, hot violaceous and tender erythema develops around the inoculation site and spreads centrifugally.

Without treatment, healing normally occurs spontaneously in 2 weeks without desquamation or suppuration.

Antibiotic therapy: Penicillin, erythromycin, and ciprofloxacin

The above image shows numerous small, shallow, circular erosions with punched-out appearance over pressure bearing area of soles, characteristic of pitted keratolysis.

It is usually associated with hyperhidrosis (not anhidrosis). Pitted keratolysis is caused most commonly due to infection by Corynebacterium and also by Kytococcus sedentarius. The pits are produced by serine proteases that can degrade keratin in the horny layer.

Most patients are unaware of the condition due to minimal irritation. This condition is diagnosed by its clinical appearance. Cultures are not useful due to mixed infections.

Treatment of hyperhidrosis slowly brings the condition under control including potassium permanganate soaks, aluminum chloride, and iontophoresis. Topical fucidin ointment may be used.