Blistering Diseases Practice Questions

Q: A 4-year-old boy presents with multiple vesicles and bullae on an erythematous base. The lesions primarily affect his elbows, knees, and buttocks, with some oral involvement. His mother reports that he gets similar lesions with minor trauma. Skin biopsy shows subepidermal separation with neutrophilic infiltrate. Direct immunofluorescence shows linear IgA deposits at the basement membrane. Which of the following is the most appropriate treatment?

Dapsone. ***Dapsone*** - The clinical presentation (vesicles and bullae on **elbows, knees, buttocks, oral involvement**, trauma-induced lesions), along with **subepidermal separation with neutrophilic infiltrate** and **linear IgA deposits** on direct immunofluorescence, is highly characteristic of **Linear IgA bullous dermatosis (LABD)**. - **Dapsone** is considered the first-line treatment for LABD due to its efficacy in reducing IgA deposition and clearing lesions. *Oral steroids* - While oral steroids can be used for acute flares or severe cases of bullous diseases, they are generally not the **first-line chronic treatment** for LABD due to significant side effects. - They also may not be as effective as dapsone in targeting the specific IgA-mediated pathology of LABD. *Azathioprine* - **Azathioprine** is an immunosuppressant often used in autoimmune bullous diseases that are **refractory to initial treatments**, or as a **steroid-sparing agent**. - It is not typically considered the first-line therapy for LABD, especially when dapsone is highly effective. *Cyclosporine* - **Cyclosporine** is another potent immunosuppressant that might be used in severe or refractory cases of autoimmune bullous diseases, but it is not the primary treatment for LABD. - Its use is limited by potential **renal toxicity** and other significant side effects.

Q: A 58-year-old woman presents with tense bullae on an erythematous base, primarily affecting her trunk and extremities. The lesions developed over the past 3 weeks. Nikolsky sign is negative. Skin biopsy shows subepidermal bullae with eosinophilic infiltrate. Direct immunofluorescence shows linear deposits of IgG and C3 at the basement membrane zone. Which of the following is the target antigen in this condition?

BP180/BP230. ***BP180/BP230*** - The clinical presentation of **tense bullae**, negative **Nikolsky sign**, subepidermal bullae with **eosinophilic infiltrate**, and **linear IgG and C3 deposition at the basement membrane zone** are classic features of **bullous pemphigoid**. - **BP180** (also known as type XVII collagen) and **BP230** are hemidesmosomal proteins that serve as the primary target antigens in bullous pemphigoid. *Type IV collagen* - **Type IV collagen** is a major component of the **basement membrane**, but it is not the target antigen in bullous pemphigoid. - Antibodies against type IV collagen may be involved in **Goodpasture syndrome**, which affects the kidneys and lungs, not primarily the skin in this manner. *Type VII collagen* - **Type VII collagen** is found in the **anchoring fibrils** beneath the basement membrane. - Antibodies against **type VII collagen** are characteristic of **epidermolysis bullosa acquisita**, which typically presents with **fragile skin, trauma-induced blistering**, and scarring, differentiating it from this case. *Desmoglein-3* - **Desmoglein-3** is a **desmosomal protein** that is a primary target antigen in **pemphigus vulgaris**, especially the **mucosal dominant form**. - **Pemphigus vulgaris** is characterized by **flaccid bullae, painful erosions**, and a **positive Nikolsky sign**, which are not consistent with the patient's presentation.

Q: A skin biopsy shows acantholysis with intraepidermal blistering. Which immunofluorescence pattern would confirm pemphigus vulgaris?

Fishnet pattern of IgG. ***Fishnet pattern of IgG*** - A **fishnet or reticular pattern** of **IgG deposition** on direct immunofluorescence (DIF) is characteristic of **pemphigus vulgaris**, indicating antibodies targeting **desmoglein 1 and 3** in the intracellular spaces of the epidermis. - This pattern corresponds to the **acantholysis** observed on biopsy, where loss of cell adhesion leads to intraepidermal blistering. *Linear IgA deposits* - **Linear IgA deposits** at the **dermal-epidermal junction** are characteristic of **linear IgA bullous dermatosis**, a blistering disorder distinct from pemphigus. - This pattern signifies **antibodies targeting components of the basement membrane zone**, not intraepidermal desmogleins. *Granular IgG deposits* - **Granular IgG deposits** in the skin are typically seen in conditions like **lupus erythematosus** or **dermatitis herpetiformis** when IgA is targeted, signifying immune complex deposition or specific antigen targeting. - This pattern is not associated with the pathogenesis of pemphigus vulgaris, which involves antibodies against desmosomal proteins. *Linear C3 deposits* - **Linear C3 deposits**, particularly at the **dermal-epidermal junction**, are a hallmark of **bullous pemphigoid**, often accompanied by linear IgG or IgA. - This indicates **complement activation** at the basement membrane zone, leading to subepidermal blistering, not the intraepidermal blistering seen in pemphigus vulgaris.

Q: Koebner's phenomenon is seen in all EXCEPT:

Pemphigoid. ***Pemphigoid*** - **Pemphigoid** is an autoimmune blistering skin condition not typically associated with the Koebner phenomenon. - In pemphigoid, **bullae** arise from an autoimmune attack on **hemidesmosomes**, not from isomorphic response to trauma. *Psoriasis* - **Psoriasis** is a classic example of a condition exhibiting the Koebner phenomenon, where isomorphic lesions develop at sites of trauma. - This response is due to **keratinocyte proliferation** triggered by injury in genetically predisposed individuals. *Warts* - **Warts** (verrucae) can demonstrate the Koebner phenomenon, meaning that new warts can emerge along a line of trauma or scratching. - This is attributed to the local spread of the **human papillomavirus (HPV)** through minor excoriations. *Lichen planus* - **Lichen planus** frequently exhibits the Koebner phenomenon, where characteristic **purplish, polygonal papules** emerge at sites of skin injury. - This isomorphic response is a common diagnostic clue in active disease.

Q: Which of the following conditions is associated with autoinoculation, where lesions spread to other body sites through scratching or direct contact?

Papilloma. ***Papilloma*** - **Papillomas** (viral warts) caused by **human papillomavirus (HPV)** are the classic example of autoinoculation in dermatology. - The virus can spread from one body site to another through **scratching, shaving, or direct contact** with the lesion. - This is particularly common with common warts, plantar warts, and flat warts, which can seed adjacent skin areas through mechanical trauma. - Autoinoculation is a hallmark feature of **viral cutaneous infections**, especially HPV-related lesions. *Bullous pemphigoid* - **Bullous pemphigoid** is an autoimmune blistering disease caused by antibodies against basement membrane zone proteins (BP180 and BP230). - Blisters arise due to **internal autoimmune processes**, not mechanical spread or autoinoculation. - While scratching may rupture blisters, this does not cause new blisters to form at distant sites—the disease distribution is determined by the autoimmune process, not by mechanical seeding. *Leukoplakia* - **Leukoplakia** is characterized by white patches on mucous membranes that cannot be scraped off and are considered **precancerous**. - It is not associated with autoinoculation or the spread of lesions through scratching. - This is a dysplastic mucosal change, not an infectious or mechanically spreadable condition. *Ameloblastoma* - **Ameloblastoma** is a rare, benign, but locally aggressive tumor of odontogenic epithelial origin, occurring mainly in the **jaws**. - It is an internal tumor and has no association with skin lesions, scratching, or autoinoculation.

Q: In congenital dystrophic variety of epidermolysis bullosa, mutation is seen in the gene coding for:

Collagen type 7. ***Correct: Collagen type 7*** - **Dystrophic epidermolysis bullosa** is characterized by defects in **collagen type 7**, which forms anchoring fibrils that connect the epidermis to the underlying dermal tissue. - Mutations in the gene *COL7A1* lead to fragile skin that **blisters easily** in the **dermo-epidermal junction** below the lamina densa (sublamina densa level). - This distinguishes it from other EB subtypes by its **sub-basement membrane zone** blistering. *Incorrect: Laminin 4* - Mutations in **laminin 332** (formerly laminin 5), not laminin 4, are associated with **junctional epidermolysis bullosa**, a different subtype. - Junctional EB primarily affects the **lamina lucida** within the dermo-epidermal junction. *Incorrect: Keratin 14* - Mutations in **keratin 5** and **keratin 14** are responsible for **epidermolysis bullosa simplex**, which involves blistering within the **basal layer of the epidermis**. - In this form, blisters occur *intraepidermally* above the basement membrane zone. *Incorrect: Alpha 6 integrin* - Mutations in **alpha 6 beta 4 integrin** subunits are also associated with **junctional epidermolysis bullosa**, specifically affecting the assembly of **hemidesmosomes**. - These defects lead to blistering within the **lamina lucida**, similar to laminin 332 mutations.

Q: All of the following statements about Stevens-Johnson Syndrome are true EXCEPT:

Systemic steroids are proven first-line therapy. ***Systemic steroids are proven first-line therapy*** - While systemic steroids are often used in the management of SJS/TEN, their efficacy as a **proven first-line therapy** remains controversial and is not universally accepted. - Many studies have shown conflicting results regarding benefits, and some evidence even suggests potential harms, particularly with high doses in early stages. *Early withdrawal of causative drug improves prognosis* - This statement is **true** because prompt identification and cessation of the offending drug are crucial for halting disease progression and improving patient outcomes in SJS. - Continued exposure to the causative agent can exacerbate the immune response, leading to more widespread epidermal necrosis and an increased risk of complications and mortality. *Nikolsky sign may be positive* - This statement is **true**. The **Nikolsky sign**, characterized by the detachment of the epidermis from the dermis with gentle lateral pressure, is a characteristic finding in SJS. - This sign indicates epidermal fragility and is a clinical manifestation of the widespread keratinocyte necrosis occurring in SJS. *SCORTEN score predicts mortality* - This statement is **true**. The **SCORTEN score** is a validated prognostic tool used to estimate the risk of death in patients with SJS and toxic epidermal necrolysis (TEN). - It assesses several clinical and laboratory parameters within the first 24-48 hours of admission to help guide management and allocate intensive care resources.

Q: Match the following autoantibodies with their associated conditions: 1. BP180 a. Pemphigus vulgaris 2. Desmoglein 3 b. Bullous pemphigoid 3. Type VII collagen c. Epidermolysis bullosa acquisita

1-b, 2-a, 3-c. ***1-b, 2-a, 3-c*** - **BP180** is an autoantigen targeted in **bullous pemphigoid**, a subepidermal blistering disease. - **Desmoglein 3** is a key autoantigen in **pemphigus vulgaris**, a life-threatening intraepidermal blistering disorder. - **Type VII collagen** is involved in anchoring fibrils and is the target of autoantibodies in **epidermolysis bullosa acquisita**, causing chronic blistering. *1-a, 2-b, 3-c* - This option incorrectly associates **BP180 with pemphigus vulgaris** and **Desmoglein 3 with bullous pemphigoid**; their associations are reversed. - While Type VII collagen is correctly linked with epidermolysis bullosa acquisita, the other pairings are incorrect. *1-c, 2-a, 3-b* - This option incorrectly links **BP180 with epidermolysis bullosa acquisita** and **Type VII collagen with bullous pemphigoid**. - While Desmoglein 3 is correctly paired with pemphigus vulgaris, the other two associations are wrong, making this overall incorrect. *1-b, 2-c, 3-a* - This option incorrectly links **Desmoglein 3 with epidermolysis bullosa acquisita** and **Type VII collagen with pemphigus vulgaris**. - While BP180 is correctly associated with bullous pemphigoid, the other two associations are incorrect.

Q: A patient with acute history of blistering and denudation involving >30% BSA along with erosions of the lips with hemorrhagic crusting and other mucosa for few days. What is the most common triggering factor?

Drug induced. ***Drug induced*** - **Toxic epidermal necrolysis (TEN)**, characterized by blistering and denudation of >30% body surface area and mucosal involvement, is most commonly triggered by **drugs**, such as sulfonamides, antiepileptics, allopurinol, and NSAIDs. - The rapid onset and severe presentation are highly suggestive of an adverse drug reaction. *Viral infection* - While viruses can trigger some mucocutaneous reactions, severe widespread necrosis and denudation like in TEN are not typically **direct viral effects**. - **Herpes simplex virus (HSV)** can cause erythema multiforme, which is less severe and extensive than TEN. *Idiopathic* - While some cases of severe cutaneous adverse reactions can be idiopathic, the vast majority of **TEN cases have an identifiable trigger**, with drugs being the leading cause. - Attributing it to an unknown cause would be less precise given the common association with medications. *Bacterial infection* - Bacterial infections, such as **Staphylococcal scalded skin syndrome (SSSS)**, can cause blistering and desquamation, but it primarily affects children and involves a superficial epidermal split, rather than the full-thickness necrosis seen in TEN. - SSSS typically spares the **mucous membranes**, unlike the prominent mucosal involvement described in the patient.

Question 1

A 4-year-old boy presents with multiple vesicles and bullae on an erythematous base. The lesions primarily affect his elbows, knees, and buttocks, with some oral involvement. His mother reports that he gets similar lesions with minor trauma. Skin biopsy shows subepidermal separation with neutrophilic infiltrate. Direct immunofluorescence shows linear IgA deposits at the basement membrane. Which of the following is the most appropriate treatment?

Accepted Answer

Dapsone

Answer

Oral steroids

Answer

Azathioprine

Answer

Cyclosporine

Question 2

A 58-year-old woman presents with tense bullae on an erythematous base, primarily affecting her trunk and extremities. The lesions developed over the past 3 weeks. Nikolsky sign is negative. Skin biopsy shows subepidermal bullae with eosinophilic infiltrate. Direct immunofluorescence shows linear deposits of IgG and C3 at the basement membrane zone. Which of the following is the target antigen in this condition?

Accepted Answer

BP180/BP230

Answer

Type IV collagen

Answer

Type VII collagen

Answer

Desmoglein-3

Question 3

A skin biopsy shows acantholysis with intraepidermal blistering. Which immunofluorescence pattern would confirm pemphigus vulgaris?

Accepted Answer

Fishnet pattern of IgG

Answer

Linear IgA deposits

Answer

Granular IgG deposits

Answer

Linear C3 deposits

Question 4

Koebner's phenomenon is seen in all EXCEPT:

Accepted Answer

Pemphigoid

Answer

Psoriasis

Answer

Warts

Answer

Lichen planus

Question 5

Which of the following conditions is associated with autoinoculation, where lesions spread to other body sites through scratching or direct contact?

Accepted Answer

Papilloma

Answer

Leukoplakia

Answer

Bullous pemphigoid

Answer

Ameloblastoma

Question 6

In congenital dystrophic variety of epidermolysis bullosa, mutation is seen in the gene coding for:

Accepted Answer

Collagen type 7

Answer

Laminin 4

Answer

Keratin 14

Answer

Alpha 6 integrin

Question 7

All of the following statements about Stevens-Johnson Syndrome are true EXCEPT:

Accepted Answer

Systemic steroids are proven first-line therapy

Answer

Early withdrawal of causative drug improves prognosis

Answer

Nikolsky sign may be positive

Answer

SCORTEN score predicts mortality

Question 8

A 70-year-old woman with bullous pemphigoid develops severe disease flare while tapering prednisone from 40mg daily. Current dose is 20mg daily. She has diabetes with HbA1c 8.5% and osteoporosis. Most appropriate next step is:

Accepted Answer

Add rituximab

Answer

Start doxycycline and niacinamide

Answer

Add azathioprine

Answer

Increase prednisone back to 40mg

Question 9

Match the following autoantibodies with their associated conditions:
1. BP180 a. Pemphigus vulgaris
2. Desmoglein 3 b. Bullous pemphigoid
3. Type VII collagen c. Epidermolysis bullosa acquisita

Accepted Answer

1-b, 2-a, 3-c

Answer

1-a, 2-b, 3-c

Answer

1-c, 2-a, 3-b

Answer

1-b, 2-c, 3-a

Question 10

A patient with acute history of blistering and denudation involving >30% BSA along with erosions of the lips with hemorrhagic crusting and other mucosa for few days. What is the most common triggering factor?

Accepted Answer

Drug induced

Answer

Viral infection

Answer

Idiopathic

Answer

Bacterial infection

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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