Blistering Diseases Practice Questions

Q: Which finding is most specific for pemphigus vulgaris?

Intercellular IgG deposits. ***Intercellular IgG deposits*** - **Direct immunofluorescence** (DIF) showing **intercellular IgG deposits** in the epidermis is the **gold standard diagnostic finding** and most specific for pemphigus vulgaris. This reflects the presence of autoantibodies targeting **desmogleins 1 and 3**, key components of desmosomes. - These antibodies disrupt cell-to-cell adhesion, leading to the characteristic **flaccid bullae** seen clinically. - This immunopathological finding has near 100% sensitivity and specificity for pemphigus vulgaris. *Suprabasal acantholysis* - While **suprabasal acantholysis** is the most characteristic **light microscopic (H&E) finding** in pemphigus vulgaris, it is a morphological consequence of the autoantibody attack and not as specific as the immunofluorescence pattern. - **Acantholysis** refers to the loss of cohesion between keratinocytes, leading to the formation of intraepidermal blisters with a characteristic "row of tombstones" appearance at the base. - This finding can occasionally be seen in other acantholytic conditions, making it less specific than DIF. *Granular IgA deposits* - **Granular IgA deposits** along the dermoepidermal junction are characteristic of **dermatitis herpetiformis**, a pruritic papulovesicular disease associated with celiac disease. - These deposits are typically found in the dermal papillae and are distinct from the intercellular IgG seen in pemphigus. *Basement membrane thickening* - **Basement membrane thickening** is a non-specific finding that can be seen in various chronic skin conditions, including **lichen sclerosus et atrophicus** or in some forms of **lupus erythematosus**. - It is not a primary or specific feature of pemphigus vulgaris, which is characterized by intraepidermal blistering due to loss of cell-to-cell adhesion.

Q: Which of the following is NOT a typical feature of erythema multiforme?

Nikolsky sign. ***Nikolsky sign*** - The **Nikolsky sign** involves the detachment of the superficial epidermis from the basal layer when lateral pressure is applied to seemingly uninvolved skin, indicative of severe blistering diseases like **pemphigus vulgaris** or **toxic epidermal necrolysis (TEN)**, but not typically **erythema multiforme (EM)**. - While EM can involve blistering, the characteristic mechanism of epidermal detachment that produces a positive Nikolsky sign is not a feature of its pathogenesis. *Triggered by HSV* - **Herpes simplex virus (HSV) infection** is the most common precipitating factor for **erythema multiforme**, particularly in its recurrent form (erythema multiforme minor). - An immune response to viral antigens deposited in the skin is thought to drive the characteristic skin lesions. *Mucosal involvement* - **Mucosal involvement** is a common feature, especially in **erythema multiforme major**, affecting the oral cavity, eyes, and/or anogenital region. - This can manifest as painful erosions and ulcers, contributing to significant morbidity. *Target lesions* - **Target lesions**, with their characteristic concentric rings of color (erythematous outer ring, pale edematous middle ring, and dusky or vesicular center), are the **hallmark skin lesion** of erythema multiforme. - These lesions are typically fixed and symmetrically distributed, often on the extremities.

Q: Which histological finding is most specific for pemphigus vulgaris?

Row of tombstones. ***Row of tombstones*** - This characteristic histological finding in **pemphigus vulgaris** refers to the appearance of a single layer of basal cells still attached to the basement membrane, resembling a **row of tombstones**, after the detachment of suprabasal epidermal cells. - It signifies **acantholysis** (loss of cell-to-cell adhesion) occurring just above the basal layer. *Basement membrane thickening* - This finding is more characteristic of conditions like **lichen sclerosus** or some chronic inflammatory dermatoses, and is not specific for pemphigus vulgaris. - It does not directly reflect the underlying immune-mediated acantholysis seen in pemphigus. *Granular IgA deposits* - **Granular IgA deposits** along the dermal-epidermal junction are the hallmark of **dermatitis herpetiformis**. - Pemphigus vulgaris is characterized by IgG autoantibodies, not IgA, targeting desmogleins. *IgG linear deposits* - **Linear IgG deposits** along the dermal-epidermal junction are characteristic of **bullous pemphigoid**, not pemphigus vulgaris. - In pemphigus vulgaris, IgG deposits are typically found in a **chicken-wire pattern** intercellularly within the epidermis.

Q: A 30-year-old male presents with flaccid bullae on an erythematous base and erosions over the oral mucous membrane. What is the most likely finding on an immunofluorescent examination of the skin biopsy of this patient?

Suprabasal deposition. ***Suprabasal deposition*** - The clinical presentation of **flaccid bullae on an erythematous base** and **oral erosions** in a young male is highly suggestive of **pemphigus vulgaris**. - **Pemphigus vulgaris** is characterized by **acantholysis** leading to separation of keratinocytes above the basal layer (suprabasal clefting), with **immunofluorescent examination** typically showing **IgG deposition** in a **fishnet or intercellular pattern** around keratinocytes in the **suprabasal epidermis**. *Subcorneal deposition* - **Subcorneal deposition** of antibodies is characteristic of diseases like **pemphigus foliaceus** or **subcorneal pustular dermatosis**. - **Pemphigus foliaceus** presents with more superficial, crusted erosions without mucosal involvement, unlike the described deep bullae and oral lesions. *Epidermal deposition* - **Epidermal deposition** is too general and non-specific, as it could refer to any level within the epidermis. - While pemphigus vulgaris does show antibody deposition within the epidermis, the specific **suprabasal location** is the key diagnostic feature that distinguishes it from other blistering disorders. *Subepidermal deposition* - **Subepidermal deposition** indicates antibody deposition at the **dermal-epidermal junction (basement membrane zone)**, typically seen in **bullous pemphigoid** or **dermatitis herpetiformis**. - These conditions present with **tense bullae** (not flaccid) due to the deeper level of splitting, and show **linear IgG and C3 deposition** at the BMZ on immunofluorescence, rather than the intercellular pattern seen in pemphigus.

Q: A 22-year-old female presents with a history of multiple small grouped vesicles on her forearm and trunk. She reports a history of celiac disease. What is the most likely diagnosis?

Dermatitis herpetiformis. ***Dermatitis herpetiformis*** - The presentation of **multiple small grouped vesicles** on the **forearm and trunk** in a patient with a history of **celiac disease** is classic for dermatitis herpetiformis. - This condition is characterized by intense **itching** and the presence of **IgA deposits** in the dermal papillae, which are strongly associated with gluten sensitivity. *Pemphigus vulgaris* - Pemphigus vulgaris typically presents with **flaccid bullae** that easily **rupture**, forming erosions, often involving mucous membranes. - It is an **autoimmune blistering disease** mediated by **IgG autoantibodies** against desmoglein 1 and 3, not associated with celiac disease. *Bullous impetigo* - Bullous impetigo is a **bacterial skin infection** characterized by **large, flaccid bullae** that typically appear in children. - It is caused by *Staphylococcus aureus* and is usually accompanied by **honey-colored crusts** upon rupture, unlike the small, grouped vesicles seen here. *Herpes simplex virus infection* - Herpes simplex virus (HSV) infection causes **grouped vesicles** on an **erythematous base**, often around the mouth or genitals. - While grouped vesicles are a feature, the **widespread distribution** on the forearm and trunk in a patient with celiac disease makes HSV less likely; HSV lesions typically recur in the same localized area.

Q: A 35-year-old man with a history of celiac disease develops cutaneous bullae on his forearms and shoulders. Histopathology shows IgA deposits at the dermal-epidermal junction. What condition is most likely?

Dermatitis herpetiformis. ***Dermatitis herpetiformis*** - The presence of **granular IgA deposits** in the **dermal papillae** (papillary dermis tips) and a history of **celiac disease** are pathognomonic for dermatitis herpetiformis. - This condition presents with intensely **pruritic vesicles** and **bullae**, often on extensor surfaces like the forearms and shoulders. - Associated with **celiac disease** in 90-95% of cases, even if asymptomatic. *Bullous pemphigoid* - Characterized by **IgG autoantibodies** targeting **hemidesmosomes** (BP180 and BP230), leading to subepidermal bullae. - Direct immunofluorescence shows **linear IgG and C3 deposits** along the basement membrane zone, not IgA. *Pemphigus vulgaris* - Involves **IgG autoantibodies** against **desmogleins 1 and 3**, causing intraepidermal blistering (acantholysis). - Direct immunofluorescence reveals a characteristic "**fish-net**" or "**chicken-wire**" pattern of **IgG and C3** deposits throughout the epidermis. *Erythema multiforme* - A **hypersensitivity reaction** often triggered by infections (e.g., **HSV**, **Mycoplasma**) or drugs, presenting with target lesions. - Histopathology shows a **lymphocytic infiltrate** targeting keratinocytes and interface dermatitis, without characteristic IgA deposits.

Q: A 65-year-old woman presents with bullous lesions on her arms and legs that rupture easily, and Nikolsky's sign is positive. What is the most likely diagnosis?

Pemphigus vulgaris. ***Pemphigus vulgaris*** - **Pemphigus vulgaris** is characterized by flaccid bullae that rupture easily, leading to erosions, and a **positive Nikolsky's sign**. - This condition involves autoantibodies against **desmoglein 1 and 3**, leading to acantholysis within the epidermis. *Bullous pemphigoid* - This condition is characterized by **tense bullae** that do not rupture easily and a **negative Nikolsky's sign**. - Autoantibodies target **hemidesmosomes**, resulting in subepidermal blistering rather than intraepidermal. *Erythema multiforme* - Typically presents with **targetoid lesions** (central blister or crust with surrounding erythema) and is often precipitated by infections or drugs. - While blistering can occur, it's not the primary feature and Nikolsky's sign is usually negative. *Dermatitis herpetiformis* - Presents with intensely **itchy papulovesicles** and is strongly associated with **celiac disease**. - The lesions are typically small, grouped vesicles, not large, flaccid bullae, and Nikolsky's sign is negative.

Q: Which condition is characterized by target lesions?

Erythema multiforme. ***Erythema multiforme*** - Erythema multiforme is classically characterized by the presence of **target lesions**, which are annular plaques with three concentric zones of color change. - These lesions often occur symmetrically on the extremities and can be triggered by infections (e.g., **herpes simplex virus**) or medications. *Psoriasis* - Psoriasis typically presents with well-demarcated, erythematous plaques covered by silvery scales, often found on extensor surfaces. - It does not involve target lesions, but rather characteristic thick, scaling patches. *Lichen planus* - Lichen planus is characterized by pruritic, polygonal, purple, planar papules and plaques (the "6 Ps"), often with fine white lines called **Wickham's striae**. - It affects the skin, hair, nails, and mucous membranes and does not exhibit target lesions. *Eczema* - Eczema (atopic dermatitis) is characterized by itchy, dry, inflamed skin, often presenting with erythema, crusting, and lichenification. - It does not produce target lesions and is typically associated with allergic responses.

Q: IgA deposition at the dermoepidermal junction is seen in?

Linear IgA disease. ***Linear IgA disease*** - This condition is characterized by a **linear deposition of IgA** at the **dermoepidermal junction**, visible on direct immunofluorescence (DIF). - The IgA deposition occurs along the **basement membrane zone**, leading to subepidermal blistering. *Dermatitis herpetiformis* - This autoimmune blistering disease is characterized by **granular IgA deposits** in the **dermal papillae**, not a linear pattern at the dermoepidermal junction. - It is strongly associated with **celiac disease** and presents with intensely pruritic vesicles. *Bullous pemphigoid* - This condition involves **linear deposition of IgG and/or C3** at the dermoepidermal junction, targeting hemidesmosomes. - While it features a linear pattern at the junction, the primary immunoglobulin involved is **IgG**, not IgA. *Epidermolysis bullosa* - This is a group of **inherited mechanobullous diseases** caused by genetic defects in structural proteins of the skin, leading to fragile skin that blisters easily with minor trauma. - It does **not involve immune-mediated deposition of IgA** or other immunoglobulins at the dermoepidermal junction.

Q: What is the antigen defect associated with Pemphigus Vulgaris?

Desmoglein-3. ***Desmoglein-3*** - Pemphigus vulgaris is characterized by **autoantibodies** primarily targeting **desmoglein-3**, a component of **desmosomes**. - This autoimmune attack leads to **acantholysis** (loss of cell adhesion) within the deep epidermis, resulting in **flaccid blisters** that rupture easily. *Desmoglein-1* - Autoantibodies against **desmoglein-1** are primarily associated with **Pemphigus Foliaceus**, which causes more superficial blistering. - While Dsg1 antibodies can be present in Pemphigus vulgaris, Dsg3 antibodies are the **main culprits** responsible for the characteristic oral lesions and widespread deep epidermal blistering. *Desmocollin-3* - **Desmocollins** are another family of **cadherin proteins** found in desmosomes, but they are not the primary target in Pemphigus vulgaris. - Antibodies against desmocollins are less common and typically do not cause the classic clinical picture of pemphigus. *Desmocollin-2* - **Desmocollin-2** is found in **desmosomes**, but it is not the main target of autoantibodies in Pemphigus vulgaris. - The disease is specifically characterized by the disruption of cell-to-cell adhesion mediated by desmogleins.

Question 1

Which finding is most specific for pemphigus vulgaris?

Accepted Answer

Intercellular IgG deposits

Answer

Granular IgA deposits

Answer

Suprabasal acantholysis

Answer

Basement membrane thickening

Question 2

Which of the following is NOT a typical feature of erythema multiforme?

Accepted Answer

Nikolsky sign

Answer

Triggered by HSV

Answer

Mucosal involvement

Answer

Target lesions

Question 3

Which histological finding is most specific for pemphigus vulgaris?

Accepted Answer

Row of tombstones

Answer

Basement membrane thickening

Answer

Granular IgA deposits

Answer

IgG linear deposits

Question 4

A 30-year-old male presents with flaccid bullae on an erythematous base and erosions over the oral mucous membrane. What is the most likely finding on an immunofluorescent examination of the skin biopsy of this patient?

Accepted Answer

Suprabasal deposition

Answer

Subcorneal deposition

Answer

Epidermal deposition

Answer

Subepidermal deposition

Question 5

A 22-year-old female presents with a history of multiple small grouped vesicles on her forearm and trunk. She reports a history of celiac disease. What is the most likely diagnosis?

Accepted Answer

Dermatitis herpetiformis

Answer

Pemphigus vulgaris

Answer

Bullous impetigo

Answer

Herpes simplex virus infection

Question 6

A 35-year-old man with a history of celiac disease develops cutaneous bullae on his forearms and shoulders. Histopathology shows IgA deposits at the dermal-epidermal junction. What condition is most likely?

Accepted Answer

Dermatitis herpetiformis

Answer

Bullous pemphigoid

Answer

Pemphigus vulgaris

Answer

Erythema multiforme

Question 7

A 65-year-old woman presents with bullous lesions on her arms and legs that rupture easily, and Nikolsky's sign is positive. What is the most likely diagnosis?

Accepted Answer

Pemphigus vulgaris

Answer

Bullous pemphigoid

Answer

Erythema multiforme

Answer

Dermatitis herpetiformis

Question 8

Which condition is characterized by target lesions?

Accepted Answer

Erythema multiforme

Answer

Psoriasis

Answer

Lichen planus

Answer

Eczema

Question 9

IgA deposition at the dermoepidermal junction is seen in?

Accepted Answer

Linear IgA disease

Answer

Dermatitis herpetiformis

Answer

Bullous pemphigoid

Answer

Epidermolysis bullosa

Question 10

What is the antigen defect associated with Pemphigus Vulgaris?

Accepted Answer

Desmoglein-3

Answer

Desmoglein-1

Answer

Desmocollin-3

Answer

Desmocollin-2

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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