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The above clinical scenario is suggestive of chronic plaque psoriasis. Axilla is usually not involved in chronic plaque psoriasis. It is affected in inverse psoriasis.

Psoriasis is a common, chronic, immune-mediated inflammatory condition in which multiple genetic and environmental factors may lead to the formation of erythematous plaques with silvery-white scales. Genetic predisposition is present in type 1 plaque psoriasis and guttate psoriasis with HLAC:06:02.

Chronic plaque psoriasis, also called psoriasis vulgaris is the most common clinical type of psoriasis. Commonly affected sites are:

• Scalp
• Elbows
• Knees
• Lower back
• Gluteal cleft

The presence of silvery-white scaly plaques on the extensor aspect of elbows and knees is a characteristic feature of psoriasis. Grattage test aids in its diagnosis.

Scratching (grattage) scales in psoriasis makes the scale appear more silver in color by introducing air–keratin interfaces. When the scales are completely scraped off, the basement membrane is exposed and is seen as a moist red surface (membrane of Bulkeley) through which dilated capillaries at the tip of elongated dermal papillae are torn, leading to multiple bleeding points.

This classical pinpoint bleeding is known as the Auspitz sign.

Auspitz sign is due to the elongated, dilated, tortuous vessels in the dermal papilla along with supra papillary thinning of the epidermis.

However, the Auspitz sign is neither sensitive nor specific for psoriasis.

Auspitz sign presen t

Psoriasis vulgaris Darrier's disease Actinic keratosis

Auspitz sign absent

Pustular psoriasis Guttate psoriasis Inverse psoriasis

Erythrodermic psoriasi s

The presence of dull red sharply demarcated plaques on the knees with loosely adherent

silvery-white scales is in favor of psoriasis. Nail plate pitting is the most common feature of nail psoriasis and is of the deep and irregular type.

About 5 to 30 of patients with cutaneous psoriasis have psoriatic arthritis(PsA). Psoriasis patients have a variable degree of pruritus.

Koebner’s phenomenon or isomorphic phenomenon, the phenomena of appearance of new lesions along the line of trauma, is seen in psoriasis.

Nail pitting is superficial and regular in alopecia areata.

Subungual oil drop sign or salmon patch (image C), a highly specific pathognomonic sign seen in nail psoriasis. It is a yellow-red discoloration in the nail bed resembling a drop of oil. The reddish-brown color is due to dilated, tortuous, superficial capillaries in the papillary dermis and parakeratosis.

The image shows sharply marginated, dull-red plaques with silvery-white scales which have coalesced to form geographical lesions. The history and image point towards a diagnosis of psoriasis. Here, there is an increased number of activated Th1, Th17, and Th22 cells, with a deficiency of Th2 cells.

It is a common, chronic, immune-mediated inflammatory condition in which multiple genetic and environmental factors may lead to the formation of erythematous plaques with silvery-white scales. Genetic predisposition is present in type 1 plaque psoriasis and guttate psoriasis

with HLAC:06:02.

There is increased keratinocyte turnover. It normally takes 30 days for basal keratinocytes to reach the surface but in patients with psoriasis, this is reduced to 4-5 days.

The activation of T cells of the adaptive immune system, specifically Th17 cells, in turn, activates keratinocytes to proliferate and produce multiple chemokines and antimicrobial peptides.

Cytokines in psoriasis:

Increased

Inflammatory cells and cytok ines

Th1 and Th17 cells

IL2, IL›, IFNγ, TNF° , IL15, IL-17, IL22, and IL

Decreased

Anti-inflammatory cells and c ytokines

Th2 cells

IL-4 and IL-10 absent

Levothyroxine is not implicated in exacerbations of psoriasis. Drugs inducing/exacerbating psoriasis:

• Beta-blockers
• Synthetic antimalarials
• NSAIDS
• Lithium
• ACE inhibitors amp; angiotensin receptor blockers
• Interferon alpha
• Tetracycline
• Terbinafine
• Gemfibrozil

Other environmental and immunological factors that may trigger psoriasis are:

• Infections- beta-hemolytic streptococci can trigger guttate psoriasis
• Alcohol misuse and smoking
• Emotional stress
• Trauma - Koebner phenomenon
• Winter
• Sunlight

The given image showing nail pitting and salmon patches in fingernails are characteristic of psoriasis. Munro microabscess is seen in psoriasis whereas Pautrier's microabscess is seen in mycosis fungoides.

Histopathological features of psoriasis:

• Irregular epidermal thickening (acanthosis)
• Hyperkeratosis and parakeratosis
• Suprapapillary thinning
• Clubbing of rete ridges at the base
• Kogoj spongiform pustules (collection of neutrophils in Malpighian layer)
• Munro microabscesses (collection of neutrophils in stratum corneum)
• Absence of stratum granulosum
• Dilated, tortuous blood vessels in the dermis
• Suprapapillary mononuclear leukocytic infiltrates

Remember: M (Munro microabscess) is seen in P (Psoriasis) and P (Pautrier’s microabscess) is seen in M (mycosis fungoides)

The image below shows histopathology of psoriasis.

Camel foot appearance is seen in histopathology of plaque-type psoriasis.

Normally, only 10 of the basal cells are in the proliferative phase, whereas in psoriasis about 90 of the basal cells are in this phase. As a result, to accommodate the increasing population of basal cells, rete pegs take a plunge in the dermis in the form of regular elongation of rete ridges, giving the 'camel foot' or clubbed appearance to epidermal rete ridges.

Other HPE findings seen in psoriasis:

• Regular acanthosis (epidermal thickening)
• Hyperkeratosis and parakeratosis
• Suprapapillary thinning
• Kogoj spongiform pustules (collection of neutrophils in Malpighian layer)
• Munro microabscesses (collection of neutrophils in stratum corneum)
• Absence of stratum granulosum
• Dilated, tortuous blood vessels in dermis
• Suprapapillary mononuclear leukocytic infiltrates

Asymmetric oligoarthritis is the most common type of psoriatic arthritis.

Psoriatic arthritis refers to an inflammatory musculoskeletal disease that has both autoimmune and autoinflammatory features characteristically occurring in individuals with psoriasis.

Asymmetric oligoarthritis commonly involves a knee or another large joint with a few small joints in the fingers or toes, often with dactylitis.

Classic psoriatic arthritis typically involves the distal interphalangeal joints.

Cone-shaped heaped-up hyperkeratotic lesions shaped like a shell (limpet) are seen in this rupioid variety of psoriasis. Valproic acid may be associated infrequently with such psoriatic flare-ups.

The term “rupioid” (from the Greek rhupos, meaning filth) is used to describe oyster or limpet shell-shaped thick keratotic lesions. In contrast to rupioid forms, regular plaque-type psoriasis has a white, nonadherent, and thin, scaly surface.

Severe psoriatic flares and atypical forms of the disease (including rupioid plaques) have been reported in HIV-positive patients and with certain drugs.

Drugs associated with psoriasis:

• β-Blockers
• Lithium
• Synthetic antimalarials
• Nonsteroidal anti-inflammatory drugs
• Tetracyclines

In inverse psoriasis, flexural plaques are thin and scaling is greatly reduced or absent.

It involves the inguinal creases, axillae, submammary folds, gluteal cleft, umbilicus, and other body folds. It is more common in older adults and is associated with obesity.

Option B: Guttate psoriasis presents with small plaque lesions with scales 2-3mm to 1 cm distributed over the trunk and proximal limbs in children

Option D: In sebopsoriasis, plaques of thin sharply demarcated erythema with variable scales may occur in the typical distribution of seborrhoeic dermatitis

Option A: Erythrodermic psoriasis has most or all of the body surface affected (gt;90BSA)

The image below shows inverse psoriasis.

The given clinical scenario points towards the diagnosis of pustular psoriasis.

Pustular psoriasis is a type of psoriasis characterized by tiny pus-filled lesions (pustules) having a characteristic lakes or sheets of pus appearance (seen in the image).

The patient presents with a history of fever and malaise along with the presence of pustules on a circumscribed, fiery red, edematous or scaling plaque. The pus is usually sterile. Sudden withdrawal of systemic steroids is usually the trigger for this condition.

Pustular psoriasis can be divided into:

• Localized pustular psoriasis
• Generalized pustular psoriasis:
• Acute generalized pustular psoriasis (Von Zumbusch)
• Subacute annular and circinate pustular psoriasis
• Acute generalized pustular psoriasis of pregnancy (Impetigo herpetiformis)

Treatment: Acitretin (oral retinoid) is the drug of choice for pustular psoriasis. However, it is contraindicated in pregnancy. Systemic steroids are used instead. Cyclosporine is the second-line drug.

Note: Systemic steroids are never used for the treatment of psoriasis except in the case of Impetigo herpetiformis where they are first-line agents.

The clinical stem of small, red, drop-like lesions on the trunk and arms (shown in the image) after an attack of pharyngitis is suggestive of guttate psoriasis.

Guttate psoriasis is a type of psoriasis occurring as a sudden onset shower of small lesions seen diffusely over the body, more on the trunk and proximal limbs. It is more common in children and young adults, following infection with group A streptococcus and is often the first presentation of psoriasis. It can also occur as a flare-up in adults with plaque psoriasis that began in childhood. It is linked to HLAC:06:02.

Lesions usually resolve over about 3 months. Some patients with acute guttate psoriasis might develop plaque psoriasis in the future.

Treatment:

• Topical steroids
• Antimicrobials - Recurrent episodes may be related to the pharyngeal carriage of the responsible streptococcus by the patient or close contact. A course of semisynthetic penicillin with rifampin may be required to clear chronic streptococcal carriage.
• Phototherapy - Broad-band ultraviolet B (UVB)- Response is better with broadband UVB over narrow-band UVB.

A chronic course is seen in plaque and follicular psoriasis.

Pustular psoriasis patients can have a fever, erythroderma, hypocalcemia, and cachexia.

Goekerman regimen is used in the treatment of psoriasis.

The modified Goekerman regimen involves application of coal tar for 5 hours/day in combination with exposure to narrowband UVB (NBUVB).

Ingram Regimen is another treatment regimen used in psoriasis. Inpatients are treated with a coal tar bath, suberythemogenic UVB and then dithranol in Lassar’s paste is applied to plaques.

The mechanism of action of dithranol may relate to its antiproliferative and proapoptotic effects on keratinocytes. Dithranol produces brown staining of the skin, which resolves about 2 weeks after therapy is completed.

Both regimens have a good safety profile and are highly efficacious.

The patient has right knee effusion, dactylitis of multiple digits, sharply demarcated red papulosquamous lesions on both knees all of which point towards a diagnosis of psoriatic arthritis.

Methotrexate and apremilast are the first-line drugs for the treatment of moderate to severe psoriasis associated with psoriatic arthritis.

Oral/systemic steroids are not used in the management of chronic plaque psoriasis. Topical steroids may be used.

Systemic steroids are avoided because the withdrawal of systemic steroids causes the development of pustular psoriasis.

The only indication of using systemic steroids in psoriasis is generalized pustular psoriasis in pregnancy (impetigo herpetiformis).

Other options maybe used in treatment of extensive (gt;30) chronic plaque psoriasis.

Impetigo herpetiformis (pustular psoriasis of pregnancy) is the only definitive indication for systemic steroids.

Steroids can also be used for the control of acute symptoms like ARDS accompanying pustular psoriasis.

Steroids are contraindicated in all other forms of psoriasis as sudden withdrawal can trigger severe pustular or erythrodermic psoriasis. As most of the other medications are contraindicated in pregnancy, this is the only definitive indication for systemic steroids.

The image shows pustular psoriasis. Acitretin, an oral retinoid is the treatment of choice for pustular psoriasis. Other first-line drugs are methotrexate and cyclosporine.

Pustular psoriasis is a complication of psoriasis wherein multiple sterile pustules develop. The acute generalized form of pustular psoriasis is termed as Von Zumbusch type.

The most provocative factor is the withdrawal of systemic corticosteroids. Steroids are relatively contraindicated except in pustular psoriasis of pregnancy (impetigo herpetiformis) where it is the treatment of choice.

Note: Tar and dithranol are absolutely contraindicated in pustular psoriasis.

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

Acitretin is approved for use in the cutaneous manifestations of psoriasis. Absolute contraindications:

• Pregnant women
• Women who are planning to get pregnant
• Breastfeeding

Relative contraindications:

• Leukopenia
• Alcoholism
• Hyperlipidemia
• Hypercholesterolemia
• Hypothyroidism
• Significant hepatic or renal disease

Brodalumab is a monoclonal antibody against the IL-17 receptor.

These biological drugs are used in cases of severe psoriasis and psoriatic arthritis.

Secukinumab and ixekizumab bind to IL-17 and prevent its binding to the receptor. They are considered IL-17 neutralizers.

Class

TNF-alpha inhibitors

IL-17 antagonists (neutralizer s)

IL-17 receptor antagonist IL-23 antagonist

IL-12/23 antagonist CD-11a antagonist

Phosphodiesterase -4 inhibit ors

Drugs

AdalimumabInfliximabEtane rceptGolimumabCertolizuma b

SecukinumabIxekizumab

Brodalumab Guselkumab

UstekinumabBriakinumab Efalizumab

Apremilast

Bullous pemphigoid is a subepidermal vesiculobullous disorder.

In bullous pemphigoid, there is subepidermal separation at the dermo-epidermal junction (DEJ).

Eosinophilic and neutrophilic infiltration are noted. It is not associated with acantholysis.

The image shows a sub-epidermal split that is suggestive of bullous pemphigoid.

As the antibodies in bullous pemphigoid are directed against BPAg2 and BPAg1 present in the basement membrane zone, intercellular junctions are intact and acantholysis is not seen.

Option A: Pemphigus vulgaris is characterized by intraepidermal (suprabasal) acantholytic blisters.

Option B: Pemphigus foliaceus shows intraepidermal (subcorneal) acantholytic blisters. Option C: In dermatitis herpetiformis, there are papillary tip micro-abscesses.

Linear IgG deposits on direct immunofluorescence (DIF) microscopy are characteristic of bullous pemphigoid. Oral erosions are a rare feature.

Bullous pemphigoid is an autoimmune disease of the elderly, between 70 to 80 years. Bullae are tense and very pruritic, mostly present on the flexural aspects of limbs and abdomen. They may reach several centimeters in size. The bullae are Nikolsky negative as acantholysis is absent.

On DIF microscopy, an n-serrated pattern is seen on 600-fold magnification.

Tense bullae over the flexor aspect that are Nikolsky negative are suggestive of bullous pemphigoid. Autoantibodies against BP180 are most commonly seen in this condition.

BP180 is also known as BPAg2 and it is seen in 75–90 of bullous pemphigoid patients. Autoantibodies against BP230 or BPAg1 are recognized in 50–70 of bullous pemphigoid patients.