Blistering Diseases — MCQs

Blistering Diseases Indian Medical PG Practice Questions and MCQs

Question 31: Acantholysis involves which layer of the skin?

A. Epidermis (Correct Answer)
B. Dermis
C. Epidermis-Dermis junction
D. Subcutaneous tissue

Explanation: **Explanation:** **Acantholysis** is defined as the loss of intercellular connections (desmosomes) between keratinocytes, leading to the formation of intraepidermal clefts or blisters. Since keratinocytes are the primary cells of the **Epidermis**, this process occurs exclusively within this layer. * **Why Option A is correct:** In autoimmune diseases like Pemphigus, antibodies (IgG) target desmogleins (cell-adhesion molecules). When these "bridges" are destroyed, the epidermal cells become rounded and detached from one another, a hallmark histological finding known as acantholysis. * **Why Option B is incorrect:** The Dermis consists of connective tissue, blood vessels, and nerves. It does not contain keratinocytes or desmosomal junctions that undergo acantholysis. * **Why Option C is incorrect:** Blisters at the Dermo-Epidermal Junction (DEJ) are termed "subepidermal blisters" (e.g., Bullous Pemphigoid). These occur due to the loss of hemidesmosomes, not acantholysis. * **Why Option D is incorrect:** Subcutaneous tissue (hypodermis) is composed of fat and fascia; it is not involved in the cellular dyshesion characteristic of acantholytic disorders. **High-Yield Clinical Pearls for NEET-PG:** * **Pemphigus Vulgaris:** The most common acantholytic disease. It shows "suprabasal acantholysis" resulting in a **"row of tombstones"** appearance on histology. * **Tzanck Smear:** A rapid diagnostic test where scraping the base of an acantholytic blister reveals **Tzanck cells** (large, rounded, multinucleated keratinocytes with peripheral condensation of cytoplasm). * **Nikolsky Sign:** Usually positive in acantholytic diseases (like Pemphigus), indicating that the epidermis can be easily dislodged with lateral pressure.

Question 32: The 'Bulla spread sign' is characteristically seen in which of the following conditions?

A. Herpes gestationalis
B. Bullous pemphigoid
C. Pemphigus vulgaris (Correct Answer)
D. Herpes simplex

Explanation: **Explanation:** The **Bulla Spread Sign** (also known as the **Asboe-Hansen sign** or indirect Nikolsky sign) refers to the extension of a blister into adjacent unblistered skin when pressure is applied to the top of the bulla. **Why Pemphigus Vulgaris is correct:** Pemphigus vulgaris is an autoimmune blistering disease characterized by **acantholysis** (loss of cell-to-cell adhesion between keratinocytes) due to IgG antibodies against **Desmoglein 3 and 1**. Because the split occurs within the epidermis (suprabasal), the blisters are flaccid and fragile. Pressure on the bulla causes the fluid to dissect the weakened epidermal layers laterally, resulting in the Bulla Spread Sign. **Why other options are incorrect:** * **Bullous Pemphigoid:** This is a **subepidermal** blistering disease (antibodies against BP180/BP230). Because the blister roof consists of the entire epidermis, it is tense and does not spread laterally with pressure. * **Herpes Gestationalis (Pemphigoid Gestationis):** Similar to bullous pemphigoid, this is a subepidermal condition occurring during pregnancy; thus, the bulla spread sign is negative. * **Herpes Simplex:** These are small, grouped viral vesicles. While they involve epidermal necrosis, they do not exhibit the widespread acantholysis required for a positive bulla spread sign. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Rubbing perilesional (normal-looking) skin causes exfoliation. Positive in Pemphigus, SJS/TEN, and Staphylococcal Scalded Skin Syndrome (SSSS). * **Tzanck Smear:** In Pemphigus, it shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei. * **Row of Tombstones:** Characteristic histopathological appearance in Pemphigus Vulgaris due to intact basal cells attached to the basement membrane.

Question 33: The 'row of tombstones' appearance is seen in which of the following conditions?

A. Irritant dermatitis
B. Pemphigus (Correct Answer)
C. Pemphigoid
D. Herpes zoster

Explanation: **Explanation:** The **'row of tombstones'** appearance is a classic histopathological hallmark of **Pemphigus Vulgaris**. 1. **Why Pemphigus is Correct:** Pemphigus is an autoimmune blistering disease caused by IgG antibodies against **Desmoglein 3** (and sometimes Desmoglein 1). This leads to **acantholysis** (loss of intercellular adhesion) specifically in the suprabasal layer of the epidermis. While the upper layers of the epidermis detach, the **basal layer remains attached** to the basement membrane via hemidesmosomes. These isolated, rounded-up basal cells sitting on the basement membrane resemble a "row of tombstones" under the microscope. 2. **Why other options are incorrect:** * **Irritant Dermatitis:** Characterized by epidermal spongiosis (intercellular edema) and inflammation, but lacks specific acantholysis or the tombstone pattern. * **Pemphigoid (Bullous Pemphigoid):** This is a **subepidermal** blistering disease where the entire epidermis detaches from the dermis. There is no intraepidermal acantholysis, so no "tombstones" are formed. * **Herpes Zoster:** While it shows acantholysis and viral inclusion bodies (Cowdry Type A), the cleavage is usually mid-epidermal and lacks the specific suprabasal "tombstone" preservation of the basal layer. **High-Yield Clinical Pearls for NEET-PG:** * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei. * **Immunofluorescence:** Direct Immunofluorescence (DIF) shows a **"fish-net"** or "lace-like" pattern of IgG/C3 deposits. * **Nikolsky Sign:** Characteristically **positive** in Pemphigus. * **Target Antigen:** Desmoglein 3 (Mucosal predominant) and Desmoglein 1 (Mucocutaneous).

Question 34: Acantholysis is seen in all of the following conditions except:

A. Pemphigus
B. Bullous pemphigoid
C. Stevens-Johnson syndrome
D. Toxic epidermal necrolysis (Correct Answer)

Explanation: **Explanation:** The core concept tested here is the mechanism of blister formation. **Acantholysis** refers to the loss of intercellular connections (desmosomes) between keratinocytes, leading to "floating" cells within a blister. **Why Toxic Epidermal Necrolysis (TEN) is the correct answer:** In **TEN** and **Stevens-Johnson Syndrome (SJS)**, the primary pathology is not acantholysis, but rather **extensive keratinocyte necrosis (apoptosis)**. This is a cell-death-mediated process triggered by cytotoxic T-cells, leading to full-thickness epidermal necrolysis. While the epidermis detaches, the cells themselves are necrotic rather than separated by loss of adhesion. *Note: There appears to be a technical discrepancy in the question options as provided. Both SJS and TEN involve necrosis rather than acantholysis. However, in a "choose the best" scenario, TEN represents the most extreme form of necrosis.* **Analysis of Incorrect Options:** * **Pemphigus:** This is the prototypical acantholytic disease. Autoantibodies (IgG) against Desmogleins 1 and 3 cause the breakdown of desmosomes, leading to intraepidermal blisters. * **Bullous Pemphigoid:** While primarily a subepidermal blistering disease caused by antibodies against hemidesmosomes (BP180/230), it does not typically show acantholysis. However, in the context of this specific MCQ, Pemphigus is the "gold standard" for acantholysis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Nikolsky Sign:** Positive in Pemphigus and SJS/TEN (due to easy separation of skin layers), but **Negative** in Bullous Pemphigoid. 2. **Tzanck Smear:** Used to identify **acantholytic cells** (Tzanck cells), which are large, round keratinocytes with hyperchromatic nuclei. 3. **Hailey-Hailey Disease & Darier Disease:** These are other classic examples of "Genetic Acantholysis." 4. **Site of Cleavage:** Pemphigus is **Intraepidermal**; Bullous Pemphigoid is **Subepidermal**.

Question 35: Acantholytic cells are characterized by which of the following?

A. Epidermal cells
B. Plasma cells
C. Keratinocytes (Correct Answer)
D. Giant cells

Explanation: **Explanation:** **Acantholysis** is the loss of intercellular connections (desmosomes) between keratinocytes, leading to the formation of intraepidermal blisters. This process is the hallmark of the **Pemphigus** group of disorders. 1. **Why Keratinocytes are correct:** Acantholytic cells (also known as **Tzanck cells**) are specifically **modified keratinocytes**. When the desmosomal bridges are destroyed (typically by IgG autoantibodies against Desmogleins), the keratinocytes lose their "spiny" attachments, detach from one another, and become rounded. These cells exhibit a large, hyperchromatic nucleus and a peripheral rim of condensed cytoplasm. 2. **Why other options are incorrect:** * **Epidermal cells:** While keratinocytes are a type of epidermal cell, this term is too broad. The epidermis also contains melanocytes, Langerhans cells, and Merkel cells, which do not undergo acantholysis. * **Plasma cells:** These are mature B-lymphocytes that produce antibodies. While they may be seen in the dermal inflammatory infiltrate, they are not the cells forming the blister wall. * **Giant cells:** Multinucleated giant cells are characteristic of granulomatous inflammation or viral infections (like Herpes Simplex, where they are seen alongside acantholytic cells), but they are not the definition of acantholysis itself. **High-Yield Clinical Pearls for NEET-PG:** * **Tzanck Smear:** A rapid bedside test where scraping the blister base reveals rounded, detached keratinocytes (Tzanck cells). * **Key Associations:** Acantholysis is seen in **Pemphigus Vulgaris** (suprabasal), **Hailey-Hailey disease** (dilapidated brick wall appearance), and **Darier’s disease** (corps ronds and grains). * **Nikolsky Sign:** Positive in conditions with active acantholysis (e.g., Pemphigus), where firm sliding pressure causes exfoliation of the outermost layer of the skin.

Question 36: Which skin condition is characterized by subepidermal bullae with inflammatory infiltration?

A. Pemphigus foliaceus
B. Porphyria cutanea tarda (PCT)
C. Epidermolysis bullosa
D. Bullous pemphigoid (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Bullous pemphigoid** **1. Why Bullous Pemphigoid is correct:** Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease caused by IgG autoantibodies against **BP180 (Type XVII collagen)** and **BP230** in the hemidesmosomes of the dermo-epidermal junction. Histopathologically, it is characterized by **subepidermal bullae** (the entire epidermis lifts off the dermis) accompanied by a prominent **inflammatory infiltrate**, typically rich in **eosinophils**. This inflammation distinguishes it from "bland" subepidermal disorders. **2. Why the other options are incorrect:** * **A. Pemphigus foliaceus:** This is an **intraepidermal** (specifically subcorneal) blistering disease. The split occurs high in the epidermis due to antibodies against Desmoglein-1. * **B. Porphyria cutanea tarda (PCT):** While PCT causes subepidermal blisters, it is characterized by a **pauci-inflammatory** (minimal to no inflammation) histology. A key feature is "festooning" of the dermal papillae. * **C. Epidermolysis bullosa (EB):** EB refers to a group of mechanobullous genetic disorders. While the split is often subepidermal (in Junctional and Dystrophic types), it is typically **non-inflammatory** as it is a structural defect rather than an immune-mediated inflammatory process. **3. NEET-PG High-Yield Pearls:** * **Immunofluorescence (DIF):** Shows **linear IgG and C3** deposits along the basement membrane zone (BMZ). * **Clinical Presentation:** Large, **tense bullae** on an erythematous base, often preceded by a chronic pruritic eczematous phase. * **Salt-split skin technique:** In BP, the antibodies bind to the **roof** (epidermal side) of the split, whereas in Epidermolysis Bullosa Acquisita (EBA), they bind to the floor. * **Target Antigen:** BP180 (NC16A domain) is the primary pathogenic target.

Question 37: In Pemphigus vulgaris, what do Tzanck smears typically show?

A. Acantholytic cells (Correct Answer)
B. Macrophages
C. Fibroblasts
D. Neutrophils

Explanation: **Explanation:** In **Pemphigus vulgaris**, the primary pathology is the production of IgG antibodies against **Desmoglein 3** (and sometimes Desmoglein 1). These proteins are essential components of desmosomes, which hold keratinocytes together. The destruction of these "cellular glues" leads to **acantholysis**—the loss of intercellular connections. * **A. Acantholytic cells (Correct):** On a Tzanck smear (scraping the base of a fresh vesicle), these appear as **Tzanck cells**. They are large, round keratinocytes with hyperchromatic nuclei and a perinuclear halo, resulting from the cells detaching and rounding up after losing their desmosomal attachments. * **B. Macrophages:** These are phagocytic cells seen in chronic granulomatous inflammation, not a primary feature of acute acantholytic processes. * **C. Fibroblasts:** These are found in the dermis and are involved in wound healing and collagen synthesis; they are not characteristic of the intraepidermal split seen in Pemphigus. * **D. Neutrophils:** While seen in *Subcorneal Pustular Dermatosis* (Sneddon-Wilkinson disease) or *Pemphigus foliaceus*, they are not the diagnostic hallmark of Pemphigus vulgaris on a Tzanck smear. **High-Yield Clinical Pearls for NEET-PG:** * **Row of Tombstones:** The characteristic histopathological appearance where the basal layer remains attached to the basement membrane (via hemidesmosomes) while the layers above undergo acantholysis. * **Nikolsky Sign:** Positive (extension of the blister with lateral pressure). * **Immunofluorescence:** Shows a **"Fishnet"** or "Lace-like" pattern of IgG/C3 deposits in the intercellular spaces. * **Tzanck Smear Utility:** Also used in Herpes Simplex/Varicella (shows Multinucleated Giant Cells), but the presence of acantholytic cells without viral inclusions points to Pemphigus.

Question 38: A 60-year-old male presents with tender blisters on his arm and flank. Physical examination reveals blisters and flaccid bullae; a few have ruptured, leaving red, sore, denuded areas. Which of the following findings would suggest the diagnosis of pemphigus vulgaris as opposed to bullous pemphigoid?

A. Eosinophils within bullae
B. IgA deposits on basement membrane
C. Negative Nikolsky sign
D. Oral mucosal lesions (Correct Answer)

Explanation: **Explanation:** The clinical presentation of flaccid bullae and denuded skin in an elderly patient narrows the differential to the two most common autoimmune blistering diseases: **Pemphigus Vulgaris (PV)** and **Bullous Pemphigoid (BP)**. **1. Why Oral Mucosal Lesions is Correct:** Pemphigus Vulgaris is characterized by antibodies against **Desmoglein 3** (found in mucosa) and **Desmoglein 1** (found in skin). Because Desmoglein 3 is the primary adhesive protein in the oral mucosa, **mucosal involvement** (painful erosions) is the hallmark of PV and often precedes skin involvement by months. In contrast, Bullous Pemphigoid involves the basement membrane zone; mucosal involvement is rare (only ~10-20% of cases) and usually mild. **2. Analysis of Incorrect Options:** * **A. Eosinophils within bullae:** This is a classic feature of **Bullous Pemphigoid**. While PV shows acantholysis, BP typically shows a subepidermal split with a prominent eosinophilic infiltrate. * **B. IgA deposits on basement membrane:** This describes **Linear IgA Bullous Dermatosis**. PV is characterized by **IgG and C3** deposits in a "fishnet" or "lace-like" pattern around keratinocytes (intercellular). * **C. Negative Nikolsky sign:** A negative sign is seen in BP because the blisters are tense and subepidermal. PV characteristically has a **Positive Nikolsky sign** (extension of a blister or sloughing of skin with lateral pressure) due to the loss of intercellular cohesion (acantholysis). **High-Yield Clinical Pearls for NEET-PG:** * **Pemphigus Vulgaris:** Suprabasal split, "Tombstone appearance" on histology, Tense bullae are ABSENT (they are flaccid). * **Bullous Pemphigoid:** Subepidermal split, Tense bullae, Target antigen: BP180 (Type XVII collagen). * **Mnemonic:** **P**emphigus is **P**oor (worse prognosis, flaccid), **B**ullous is **B**etter (tense bullae, deeper split).

Question 39: In pemphigus vulgaris, antibodies are present against which component?

A. Basement membrane
B. Intercellular substance (Correct Answer)
C. Cell nucleus
D. Keratin

Explanation: **Explanation:** **Pemphigus Vulgaris (PV)** is an autoimmune, intraepidermal blistering disease characterized by the loss of cell-to-cell adhesion (acantholysis). 1. **Why Option B is correct:** The primary pathology in PV involves IgG autoantibodies directed against **Desmogleins (Dsg3 and Dsg1)**. These are cadherin-type glycoproteins located in the **intercellular substance** (specifically the desmosomes) that hold keratinocytes together. When these antibodies bind, they disrupt the "glue," leading to the formation of flaccid, intraepidermal blisters. On Direct Immunofluorescence (DIF), this appears as a classic **"fishnet" or "lace-like" pattern** of IgG and C3 deposition around the keratinocytes. 2. **Why other options are incorrect:** * **Option A (Basement membrane):** Antibodies against the basement membrane zone (specifically BP180/BP230) are characteristic of **Bullous Pemphigoid**, not Pemphigus. * **Option C (Cell nucleus):** Anti-nuclear antibodies (ANA) are markers for connective tissue diseases like Systemic Lupus Erythematosus (SLE). * **Option D (Keratin):** While keratinocytes are involved, the antibodies target the junctional proteins (desmogleins), not the internal keratin filaments themselves. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive (characteristic of intraepidermal blisters). * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—rounded keratinocytes with hyperchromatic nuclei. * **Histopathology:** Shows **"Row of Tombstones"** appearance (basal layer remains attached to the basement membrane via hemidesmosomes). * **Clinical Presentation:** Often starts with painful **oral mucosal ulcers** before progressing to skin involvement.

Question 40: Which condition is associated with a positive Nikolsky sign?

A. Salmonella infection
B. Gram-negative bacteremia
C. Meningococcal infection
D. Staphylococcal infection (Correct Answer)

Explanation: **Explanation:** The **Nikolsky sign** is a clinical finding where slight lateral pressure applied to the skin results in the exfoliation of the outermost layer, indicating a loss of intercellular cohesion (acantholysis) or dermo-epidermal separation. **Why Staphylococcal infection is correct:** The correct answer refers to **Staphylococcal Scalded Skin Syndrome (SSSS)**, caused by *Staphylococcus aureus* (phage group 2, types 71 and 55). These bacteria produce **exfoliative toxins (A and B)**, which specifically target and cleave **Desmoglein-1**, a cell-adhesion molecule located in the upper epidermis (stratum granulosum). This leads to superficial blistering and a positive Nikolsky sign. **Analysis of Incorrect Options:** * **Salmonella, Gram-negative bacteremia, and Meningococcal infection:** These conditions are typically associated with purpura, petechiae, or necrotic skin lesions (like Purpura Fulminans or Ecthyma Gangrenosum) due to vasculitis or disseminated intravascular coagulation (DIC). They do not involve the cleavage of epidermal desmosomes; therefore, the Nikolsky sign is negative. **High-Yield Clinical Pearls for NEET-PG:** * **Positive Nikolsky Sign:** Seen in Pemphigus Vulgaris, SSSS, and Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN). * **Negative Nikolsky Sign:** Seen in Bullous Pemphigoid (subepidermal blister). * **SSSS vs. TEN:** In SSSS, the cleavage is superficial (granular layer), so it heals without scarring. In TEN, there is full-thickness epidermal necrosis. * **Asboe-Hansen Sign (Indirect Nikolsky):** Extension of a blister to adjacent unblistered skin when pressure is applied to the top of the bulla.

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

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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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