Blistering Diseases — MCQs

A 65-year-old man has developed pruritus followed by blistering skin lesions over the trunk, legs, and arms over the past month. On physical examination, there are 1- to 4-cm tense bullae, particularly over flexural surfaces of the skin. A biopsy of one lesion is examined microscopically by direct immunofluorescence staining and shows a subepidermal bulla, with both IgG and C3 deposited linearly along the dermal-epidermal junction. He is treated with topical corticosteroids, and a month later the lesions are healed without scarring. Which of the following components of the skin has most likely been targeted by an autoantibody in this man?

Q107Medium

A 56-year-old male presents with a painful bullous lesion in his lower extremity. What is the most likely diagnosis?

Q108Easy

Intraepidermal bullae formation occurs in which of the following conditions?

Q109Easy

Trismus is not seen in which of the following conditions?

Q110Medium

A twenty-one-year-old woman complains that regular, gentle brushing of her teeth is painful and causes profuse bleeding. Oral examination reveals the loss of epithelium from the attached gingiva of both arches. Which of the following dermatological problems is this patient most likely to have?

Blistering Diseases Indian Medical PG Practice Questions and MCQs

Question 101: Acantholysis is seen in which of the following conditions?

A. Psoriasis
B. Pemphigus vulgaris (Correct Answer)
C. Lichen planus
D. Pityriasis versicolor

Explanation: **Explanation:** **Acantholysis** is the primary pathological process in **Pemphigus vulgaris**. It refers to the loss of intercellular connections (desmosomes) between keratinocytes, leading to the formation of intraepidermal clefts and blisters. In Pemphigus vulgaris, IgG autoantibodies target **Desmoglein 3** (and sometimes Desmoglein 1), causing the cells to detach and float freely, often described as "acantholytic cells" or **Tzanck cells**. **Analysis of Options:** * **Psoriasis (A):** Characterized by epidermal hyperplasia (acanthosis), parakeratosis, and Munro’s microabscesses, but not acantholysis. * **Lichen Planus (C):** A chronic inflammatory condition featuring "saw-tooth" rete ridges and a band-like lymphocytic infiltrate at the dermo-epidermal junction (interface dermatitis). * **Pityriasis Versicolor (D):** A superficial fungal infection caused by *Malassezia furfur*, characterized by "spaghetti and meatballs" appearance on KOH mount, involving only the stratum corneum. **NEET-PG High-Yield Pearls:** * **Nikolsky Sign:** Positive in Pemphigus vulgaris (due to acantholysis) but negative in Bullous Pemphigoid. * **Tzanck Smear:** Shows rounded, nucleated acantholytic cells with a peripheral halo of cytoplasm. * **Row of Tombstones:** The characteristic histopathological appearance where the basal layer remains attached to the basement membrane while the layers above undergo acantholysis. * **Immunofluorescence:** Shows a "fishnet" or "reticular" pattern of IgG/C3 deposition.

Question 102: A middle-aged female presents with flaccid bullae in the skin and oral erosions. Histopathology reveals intraepidermal acantholytic blisters. What is the most likely diagnosis?

A. Bullous pemphigoid
B. Paraneoplastic pemphigus
C. Dermatitis herpetiformis
D. Pemphigus vulgaris (Correct Answer)

Explanation: **Explanation:** **Pemphigus Vulgaris (PV)** is the correct diagnosis based on the classic triad of clinical and histological findings: middle-aged presentation, involvement of oral mucosa, and **intraepidermal acantholytic blisters**. The underlying pathophysiology involves IgG autoantibodies against **Desmoglein 3** (and sometimes Desmoglein 1), which are components of desmosomes. The loss of cell-to-cell adhesion (acantholysis) leads to the formation of **flaccid bullae** that rupture easily, leaving painful erosions. Because the split occurs just above the basal layer, it creates the characteristic "tombstone appearance" on histopathology. **Why other options are incorrect:** * **Bullous Pemphigoid:** Characterized by **tense bullae** (not flaccid) and rarely involves the oral mucosa. Histologically, it shows **subepidermal** blisters with eosinophils, caused by antibodies against BP180/BP230. * **Paraneoplastic Pemphigus:** While it presents with severe mucosal erosions, it is typically associated with an underlying malignancy (e.g., Non-Hodgkin Lymphoma) and shows a polymorphic rash (including lichenoid lesions), which is not described here. * **Dermatitis Herpetiformis:** Presents as extremely pruritic, grouped vesicles on extensor surfaces. Histology shows subepidermal blisters with **neutrophilic microabscesses** at the dermal papillary tips; it is strongly associated with Celiac disease. **NEET-PG High-Yield Pearls:** * **Nikolsky Sign:** Positive in Pemphigus Vulgaris (extension of blister with lateral pressure). * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei. * **Direct Immunofluorescence (DIF):** Shows a characteristic **"fishnet" or "lace-like" pattern** of IgG and C3 deposits in the intercellular spaces.

Question 103: Desquamative gingivitis represents oral manifestations of all of the following except:

A. Erosive lichen planus.
B. Benign mucous membrane pemphigoid.
C. Erythema multiforme. (Correct Answer)
D. Pemphigus.

Explanation: **Explanation:** **Desquamative gingivitis (DG)** is a clinical term, not a diagnosis, describing a condition where the gingiva appears erythematous, glazed, and friable with a tendency for the epithelium to peel off (desquamate). It is primarily a manifestation of chronic mucocutaneous autoimmune diseases. **Why Erythema Multiforme (EM) is the correct answer:** Erythema Multiforme is an **acute, self-limiting** hypersensitivity reaction (often triggered by HSV or drugs). While it frequently involves the oral mucosa with painful erosions and characteristic hemorrhagic crusting of the lips, it does not present as chronic desquamative gingivitis. DG is defined by its **chronicity**, whereas EM follows an acute course. **Analysis of Incorrect Options:** * **Erosive Lichen Planus:** This is the **most common** cause of desquamative gingivitis. It presents with the classic "Wickham’s striae" at the periphery of the desquamative areas. * **Cicatricial (Benign Mucous Membrane) Pemphigoid:** This is the **second most common** cause. It is a subepidermal blistering disease where gingival involvement is often the first or only sign. * **Pemphigus Vulgaris:** An intraepidermal autoimmune disease where oral lesions (including DG) often precede skin lesions. A positive Nikolsky sign can often be elicited on the gingiva. **High-Yield Clinical Pearls for NEET-PG:** 1. **Top 3 causes of DG:** Lichen Planus > Cicatricial Pemphigoid > Pemphigus Vulgaris. 2. **Nikolsky Sign:** Positive in Pemphigus; negative in Lichen Planus. 3. **Target Lesions:** Pathognomonic for Erythema Multiforme (usually on extremities), not seen in chronic DG. 4. **Histopathology Requirement:** A biopsy with Direct Immunofluorescence (DIF) is essential to differentiate the underlying causes of desquamative gingivitis.

Question 104: Which condition is characterized by severe bullous erythema multiforme with oral, ocular, and genital lesions?

A. Stevens-Johnson syndrome (Correct Answer)
B. Darier's disease
C. Reiter syndrome
D. All of the above

Explanation: **Explanation:** **Stevens-Johnson Syndrome (SJS)** is a severe, immune-mediated mucocutaneous reaction, most commonly triggered by drugs (e.g., sulfonamides, anticonvulsants, NSAIDs). It is characterized by the sudden onset of high fever, malaise, and widespread **bullous erythema multiforme-like lesions** (atypical target lesions). The hallmark of SJS is the involvement of at least **two or more mucosal surfaces**, typically the oral cavity (hemorrhagic crusting of lips), ocular (conjunctivitis/ulceration), and genital mucosa. Pathologically, it involves extensive keratinocyte apoptosis leading to epidermal detachment of **<10% of the total body surface area (BSA)**. **Why other options are incorrect:** * **Darier’s Disease:** An autosomal dominant genodermatosis (ATP2A2 mutation) characterized by greasy, keratotic papules in seborrheic areas and nail changes (V-shaped nicking). It is not an acute bullous or mucosal syndrome. * **Reiter Syndrome (Reactive Arthritis):** Characterized by the triad of urethritis, arthritis, and conjunctivitis ("Can't see, can't pee, can't climb a tree"). While it involves mucosa, the skin lesions are typically *keratoderma blennorrhagica* (psoriasiform lesions on palms/soles), not bullous erythema multiforme. **High-Yield NEET-PG Pearls:** * **SJS vs. TEN:** SJS involves <10% BSA; TEN (Toxic Epidermal Necrolysis) involves >30% BSA; 10-30% is the SJS/TEN overlap. * **Nikolsky Sign:** Positive in SJS/TEN (epidermal detachment with lateral pressure). * **Most common cause:** Drugs are the primary trigger (Sulfonamides are the most frequent culprits). * **Histopathology:** Shows subepidermal bullae with full-thickness epidermal necrosis.

Question 105: A 60-year-old patient presented with several bullous lesions for the last 3 days; each bulla was surrounded by an erythematous halo. There were multiple target lesions and oral erosions. What is the most likely diagnosis?

A. Chickenpox
B. Herpes simplex
C. Herpes zoster
D. Stevens-Johnson syndrome (Correct Answer)

Explanation: **Explanation:** The clinical presentation of **bullous lesions with erythematous halos**, **targetoid lesions**, and **mucosal involvement (oral erosions)** in an adult is classic for **Stevens-Johnson Syndrome (SJS)**. SJS is a severe mucocutaneous hypersensitivity reaction, most commonly triggered by drugs (e.g., sulfonamides, anticonvulsants, NSAIDs). The "target lesions" in SJS are typically "atypical" (two zones) compared to the "classic" targets (three zones) seen in Erythema Multiforme. **Why the other options are incorrect:** * **Chickenpox (Varicella):** Characterized by a pleomorphic rash (macules, papules, and vesicles in different stages) described as "dewdrops on a rose petal." It lacks target lesions and extensive bullae. * **Herpes Simplex:** Usually presents as localized, grouped vesicles on an erythematous base (e.g., cold sores). While it can trigger Erythema Multiforme, the primary infection itself does not present with generalized bullae and targetoid lesions. * **Herpes Zoster:** Presents as painful, unilateral vesicles following a specific dermatomal distribution. It does not cause generalized target lesions or widespread bullae. **Clinical Pearls for NEET-PG:** * **SJS vs. TEN:** The distinction is based on the Body Surface Area (BSA) of epidermal detachment: **SJS <10%**, **SJS/TEN overlap 10-30%**, and **Toxic Epidermal Necrolysis (TEN) >30%**. * **Nikolsky Sign:** Usually positive in SJS/TEN (epidermal shearing with lateral pressure). * **Histology:** Shows full-thickness epidermal necrosis and subepidermal clefting. * **Common Triggers:** Remember the mnemonic **SATAN** (Sulfa drugs, Allopurinol, Tetracyclines, Anticonvulsants, NSAIDs).

Question 106: A 65-year-old man has developed pruritus followed by blistering skin lesions over the trunk, legs, and arms over the past month. On physical examination, there are 1- to 4-cm tense bullae, particularly over flexural surfaces of the skin. A biopsy of one lesion is examined microscopically by direct immunofluorescence staining and shows a subepidermal bulla, with both IgG and C3 deposited linearly along the dermal-epidermal junction. He is treated with topical corticosteroids, and a month later the lesions are healed without scarring. Which of the following components of the skin has most likely been targeted by an autoantibody in this man?

A. Hemidesmosome (Correct Answer)
B. Keratinocyte cell membrane
C. Lamina densa
D. Nucleus

Explanation: ### Explanation The clinical presentation and immunofluorescence findings are diagnostic of **Bullous Pemphigoid (BP)**. **1. Why Hemidesmosome is Correct:** Bullous Pemphigoid is an autoimmune subepidermal blistering disease typically affecting the elderly. The pathophysiology involves autoantibodies (IgG) targeting **BP180 (Type XVII collagen)** and **BP230**, which are key components of the **hemidesmosomes**. Hemidesmosomes anchor the basal keratinocytes to the basement membrane. Damage to these structures leads to the separation of the epidermis from the dermis, resulting in **tense bullae** (because the entire epidermal roof is intact) and a **linear deposition of IgG and C3** along the dermal-epidermal junction (DEJ) on direct immunofluorescence (DIF). **2. Why the Other Options are Incorrect:** * **Keratinocyte cell membrane:** This is the target in **Pemphigus Vulgaris** (specifically Desmoglein 1 and 3 in desmosomes). This results in intraepidermal, flaccid blisters and a "fishnet" pattern on DIF. * **Lamina densa:** This layer of the basement membrane is targeted in **Epidermolysis Bullosa Acquisita (EBA)** (Type VII collagen). While EBA also shows linear IgG, it typically presents with scarring and milia, unlike BP. * **Nucleus:** Antinuclear antibodies (ANA) are characteristic of systemic autoimmune diseases like **Systemic Lupus Erythematosus (SLE)**, not primary blistering skin diseases. **3. Clinical Pearls for NEET-PG:** * **Age Group:** Typically >60 years. * **Clinical Feature:** Tense bullae on an erythematous base; often preceded by a "pre-bullous" pruritic phase. * **DIF Pattern:** Linear IgG and C3 at the DEJ (**"n-serrated" pattern**). * **Salt-split skin test:** Fluorescence is seen on the **roof** (epidermal side) of the blister, distinguishing it from EBA (where it is on the floor). * **Prognosis:** Generally good; heals **without scarring** (unlike Pemphigoid Cicatricial).

Question 107: A 56-year-old male presents with a painful bullous lesion in his lower extremity. What is the most likely diagnosis?

A. Pemphigus Vulgaris
B. Bullous Pemphigoid (Correct Answer)
C. Necrotic Pemphigus
D. Contact Eczema

Explanation: ***Bullous Pemphigoid*** - **Tense, painful bullae** on the **lower extremities** in an **elderly patient** (56-year-old) is characteristic of bullous pemphigoid, which commonly affects patients over 60. - The **Nikolsky sign is negative** and targets **BP180/BP230 antigens** at the dermal-epidermal junction, creating subepidermal blisters that are typically tense and painful. *Pemphigus Vulgaris* - Characterized by **flaccid, fragile bullae** that rupture easily, unlike the tense bullae described in this case. - Typically involves **mucosal surfaces** (oral cavity) and has a **positive Nikolsky sign** due to intraepidermal acantholysis. *Necrotic Pemphigus* - This is not a recognized clinical entity in standard dermatological classification of **autoimmune blistering diseases**. - **Pemphigus variants** include vulgaris, foliaceus, and paraneoplastic, but "necrotic pemphigus" is not an established diagnosis. *Contact Eczema* - Presents with **erythema, scaling, and vesicles** rather than large tense bullae as described in this case. - Typically has a clear **history of allergen exposure** and responds to **topical corticosteroids** and allergen avoidance.

Question 108: Intraepidermal bullae formation occurs in which of the following conditions?

A. Bullous Impetigo
B. Bullous pemphigoid
C. Pemphigus vulgaris (Correct Answer)
D. Dermatitis herpetiformis

Explanation: **Explanation:** The level of split (cleavage) within the skin layers is the fundamental diagnostic feature in blistering diseases. **1. Why Pemphigus Vulgaris is Correct:** Pemphigus vulgaris is the prototype of **intraepidermal** blistering. It is an autoimmune disease where IgG antibodies target **Desmoglein 3** (and sometimes Desmoglein 1), which are components of desmosomes. The loss of cell-to-cell adhesion between keratinocytes is called **acantholysis**, leading to the formation of a "suprabasal" split. Because the roof of the blister is thin epidermis, these bullae are typically flaccid and rupture easily. **2. Why the other options are incorrect:** * **Bullous Impetigo:** While this also involves an intraepidermal split (specifically subcorneal), it is caused by staphylococcal exfoliative toxins targeting Desmoglein 1. However, in the context of classic "blistering diseases" exams, Pemphigus is the primary intraepidermal representative. * **Bullous Pemphigoid:** This is a **subepidermal** blistering disease. Antibodies target BP180 and BP230 in the hemidesmosomes at the dermo-epidermal junction. These blisters are tense and do not rupture easily. * **Dermatitis Herpetiformis:** This is also a **subepidermal** condition associated with Celiac disease. It is characterized by IgA deposits in the dermal papillae tips, leading to "micro-abscesses" and subepidermal clefting. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in Pemphigus (intraepidermal) and negative in Bullous Pemphigoid (subepidermal). * **Tzanck Smear:** Shows "Acantholytic cells" (Tzanck cells) in Pemphigus. * **Row of Tombstones:** The characteristic histopathological appearance of the basal layer in Pemphigus Vulgaris. * **Direct Immunofluorescence (DIF):** "Fish-net" or "Lace-like" pattern in Pemphigus; "Linear" pattern at the basement membrane in Bullous Pemphigoid.

Question 109: Trismus is not seen in which of the following conditions?

A. Scleroderma
B. Oral submucous fibrosis (OSMF)
C. Pemphigus (Correct Answer)
D. None of the above

Explanation: **Explanation:** The core concept behind this question is the mechanism of limited mouth opening. **Trismus** (lockjaw) or restricted mouth opening in dermatology and oral medicine typically results from **fibrosis** of the submucosal tissues or the skin surrounding the oral commissure, rather than simple mucosal ulceration. * **Why Pemphigus is the correct answer:** Pemphigus vulgaris is an autoimmune blistering disease characterized by acantholysis (loss of cell-to-cell adhesion). While it frequently involves the oral mucosa with painful erosions, it **does not cause fibrosis or scarring**. Because the tissue remains pliable and does not undergo cicatrization, the mechanical ability to open the mouth remains intact (though it may be painful). * **Why the other options are incorrect:** * **Scleroderma:** Systemic sclerosis leads to excessive collagen deposition. This causes "microstomia" (small mouth) due to the tightening and hardening of the perioral skin, significantly limiting mouth opening. * **Oral Submucous Fibrosis (OSMF):** This is a premalignant condition (strongly associated with areca nut chewing) characterized by juxta-epithelial inflammatory reaction followed by **progressive hyalinization and fibrosis** of the lamina propria. The resulting stiff, fibrous bands directly cause severe trismus. **High-Yield Clinical Pearls for NEET-PG:** * **Pemphigus Vulgaris:** Key features include Nikolsky sign (+), Tzanck cells (acantholytic cells), and "row of tombstones" appearance on histology. It heals **without scarring**. * **Cicatricial Pemphigoid:** Unlike Pemphigus, this *can* cause scarring (hence the name "cicatricial"), but it primarily affects the conjunctiva and mucosa. * **OSMF:** Look for "burning sensation on eating spicy food" and "blanching of oral mucosa" in the clinical stem.

Question 110: A twenty-one-year-old woman complains that regular, gentle brushing of her teeth is painful and causes profuse bleeding. Oral examination reveals the loss of epithelium from the attached gingiva of both arches. Which of the following dermatological problems is this patient most likely to have?

A. Benign mucous membrane pemphigoid (Correct Answer)
B. Chronic discoid lupus erythematosus
C. Pemphigus
D. Psoriasis

Explanation: The clinical presentation of painful, bleeding gums with loss of epithelium from the attached gingiva is the classic description of **Desquamative Gingivitis**. ### **Why Option A is Correct** **Cicatricial Pemphigoid (Benign Mucous Membrane Pemphigoid)** is the most common cause of desquamative gingivitis. It is an autoimmune subepidermal blistering disease where antibodies target the basement membrane zone (specifically BP180/Laminin 332). Unlike Pemphigus, it primarily affects mucous membranes (oral, ocular, genital) and often leads to scarring (cicatrix). The "peeling" of the gingiva upon gentle brushing is a hallmark sign. ### **Why Other Options are Incorrect** * **B. Chronic Discoid Lupus Erythematosus (CDLE):** While it can cause oral ulcers, they typically present as central erythema with peripheral radiating white striae (honeycomb pattern), usually on the buccal mucosa, not generalized desquamative gingivitis. * **C. Pemphigus:** Pemphigus vulgaris frequently involves the mouth, but it presents as fragile, ragged, non-healing ulcers and erosions on the soft palate and buccal mucosa. While it can cause desquamative gingivitis, it is statistically less common than Pemphigoid for this specific presentation and usually involves other skin sites with a positive Nikolsky sign. * **D. Psoriasis:** Oral psoriasis is extremely rare. It typically presents as "geographic tongue" (erythema migrans) rather than desquamative gingivitis. ### **NEET-PG High-Yield Pearls** * **Desquamative Gingivitis:** Not a diagnosis but a clinical sign. Top 3 causes: 1. Cicatricial Pemphigoid, 2. Lichen Planus, 3. Pemphigus Vulgaris. * **Ocular Involvement:** In Mucous Membrane Pemphigoid, always check the eyes for **symblepharon** (adhesion of eyelid to eyeball), as it can lead to blindness. * **Histopathology:** Pemphigoid shows **subepidermal** blisters with linear IgG/C3 at the BMZ on Direct Immunofluorescence (DIF).

Practice by Chapter

Pemphigus Vulgaris

Practice Questions

Pemphigus Foliaceus

Practice Questions

Bullous Pemphigoid

Practice Questions

Cicatricial Pemphigoid

Practice Questions

Dermatitis Herpetiformis

Practice Questions

Epidermolysis Bullosa

Practice Questions

Linear IgA Bullous Dermatosis

Practice Questions

Pemphigoid Gestationis

Practice Questions

Drug-Induced Bullous Disorders

Practice Questions

Immunofluorescence in Bullous Diseases

Practice Questions

Management of Autoimmune Bullous Diseases

Practice Questions

Genetic Counseling in Inherited Blistering Diseases

Practice Questions

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