Blistering Diseases Practice Questions

Q: What is true about erythema multiforme?

All of the above.. **Erythema Multiforme (EM)** is an acute, self-limiting Type IV hypersensitivity reaction, most commonly triggered by infections (especially **Herpes Simplex Virus**). **Explanation of Options:** * **A. Target lesions are characteristic:** The hallmark of EM is the "target" or "iris" lesion. These consist of three distinct zones: a central dusky/blistering area, a pale edematous ring, and an outer erythematous halo. They typically appear symmetrically on the acral extremities (hands and feet). * **B. Hemorrhagic crusts on lips:** In Erythema Multiforme Major, mucosal involvement is prominent. The oral mucosa is frequently affected, leading to painful erosions and the classic appearance of "bloody" or hemorrhagic crusting on the lips. * **C. Lesions resolve over 3 to 6 weeks:** EM is a self-limiting condition. Individual lesions may appear over 3–5 days and typically resolve without scarring within 2 to 4 weeks (EM Minor) or up to 6 weeks (EM Major). **Why "All of the above" is correct:** All three statements accurately describe the clinical morphology, mucosal presentation, and natural history of the disease. **High-Yield NEET-PG Pearls:** * **Most Common Trigger:** HSV-1 and HSV-2 (associated with EM Minor). *Mycoplasma pneumoniae* is the most common bacterial cause (associated with EM Major). * **Classification:** * **EM Minor:** Minimal or no mucosal involvement; no systemic symptoms. * **EM Major:** Involvement of at least one mucosal surface; systemic symptoms (fever, malaise) present. * **Important Distinction:** EM is no longer considered part of the same spectrum as Stevens-Johnson Syndrome (SJS)/Toxic Epidermal Necrolysis (TEN). EM is usually post-infectious, while SJS/TEN is drug-induced. * **Histology:** Shows "satellite cell necrosis" (individual necrotic keratinocytes surrounded by lymphocytes).

Q: A patient presents with tense bullae on an erythematous base. What is seen on histopathological examination?

Subepidermal split. **Explanation:** The clinical presentation of **tense bullae on an erythematous base** is the hallmark of **Bullous Pemphigoid (BP)**. In BP, autoantibodies (anti-BP180 and anti-BP230) target the hemidesmosomes at the dermo-epidermal junction. Because the entire thickness of the epidermis remains intact as the "roof" of the blister, the bullae are structurally strong and "tense," leading to a **subepidermal split** on histopathology. **Analysis of Options:** * **Subepidermal split (Correct):** Characteristic of Bullous Pemphigoid, Dermatitis Herpetiformis, and Epidermolysis Bullosa Acquisita. The split occurs below the epidermis, resulting in a non-flaccid blister. * **Subcorneal split (Incorrect):** Seen in **Pemphigus Foliaceus** and Staphylococcal Scalded Skin Syndrome (SSSS). The split is very superficial (just below the stratum corneum), leading to very fragile, erosive lesions rather than tense bullae. * **Fishnet pattern (Incorrect):** This refers to the **Direct Immunofluorescence (DIF)** finding in Pemphigus Vulgaris, where IgG deposits around keratinocytes in the epidermis. It is an immunopathological finding, not a histopathological split level. * **Row of tombstone appearance (Incorrect):** A classic histopathological feature of **Pemphigus Vulgaris**. It occurs due to suprabasal acantholysis, where the basal layer remains attached to the basement membrane while the upper layers detach. **High-Yield Clinical Pearls for NEET-PG:** * **Bullous Pemphigoid:** Most common autoimmune blistering disease in the elderly. DIF shows **linear IgG and C3** along the basement membrane zone. * **Pemphigus Vulgaris:** Characterized by **flaccid bullae**, positive Nikolsky sign, and oral mucosal involvement (unlike BP, which rarely involves mucosa). * **Mnemonic:** **B**ullous **P**emphigoid = **B**elow the epidermis (Subepidermal) + **B**asement membrane.

Q: What is the commonest and rarest variety of Pemphigus?

Pemphigus vulgaris/Pemphigus vegetans. **Explanation:** Pemphigus is a group of autoimmune blistering diseases characterized by acantholysis (loss of intercellular connections) due to antibodies against desmogleins. 1. **Why Option A is correct:** * **Pemphigus Vulgaris (PV):** This is the **most common** variety worldwide, accounting for approximately 70% of all pemphigus cases. It involves antibodies against Desmoglein 3 (mucosal-dominant) and Desmoglein 1 (mucocutaneous). It typically presents with flaccid bullae and painful oral erosions. * **Pemphigus Vegetans:** This is a rare variant of PV and is considered the **rarest** variety. It is characterized by vegetating plaques, particularly in intertriginous areas (axilla, groin), and is divided into Neumann and Hallopeau types. 2. **Why other options are incorrect:** * **Option B:** Reverses the order; PV is common, not rare. * **Option C & D:** **Pemphigus Foliaceus (PF)** is the second most common variety but is more superficial (subcorneal) than PV. **Pemphigus Erythematosus (Senear-Usher Syndrome)** is a localized variant of PF that overlaps with Lupus Erythematosus; while less common than PV, it is not as rare as the vegetans variety. **NEET-PG High-Yield Pearls:** * **Target Antigens:** PV = Desmoglein 3 > 1; PF = Desmoglein 1. * **Histopathology:** PV shows "Row of Tombstones" appearance (suprabasal split). PF shows subcorneal split. * **Clinical Signs:** Nikolsky sign and Bulla Spread sign (Asboe-Hansen) are positive in all active pemphigus variants. * **Tzanck Smear:** Shows rounded, detached keratinocytes with hyperchromatic nuclei (Acantholytic/Tzanck cells).

Q: Which of the following disorders is associated with acantholysis?

Pemphigus vulgaris. **Explanation:** **Acantholysis** is the loss of intercellular connections (desmosomes) between keratinocytes, leading to the formation of intraepidermal blisters. **1. Why Pemphigus Vulgaris is Correct:** Pemphigus vulgaris is the classic example of an **intraepidermal** autoimmune blistering disease. It is caused by IgG antibodies against **Desmoglein 3** (and sometimes Desmoglein 1). The destruction of these desmosomal proteins leads to acantholysis, resulting in "tombstoning" of the basal layer and the formation of flaccid bullae. **2. Why Other Options are Incorrect:** * **Pemphigoid (Bullous Pemphigoid):** This is a **subepidermal** blistering disease. The pathology involves antibodies against BP180/BP230 in the hemidesmosomes. There is no loss of keratinocyte-to-keratinocyte adhesion (no acantholysis). * **Erythema Multiforme:** This is a hypersensitivity reaction characterized by keratinocyte necrosis and subepidermal separation, typically triggered by HSV or drugs. It does not involve primary acantholysis. * **Dermatitis Herpetiformis:** This is an IgA-mediated disease associated with Celiac disease. It is characterized by **subepidermal** blisters and neutrophilic microabscesses at the dermal papillary tips. **Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in Pemphigus (due to acantholysis) but negative in Bullous Pemphigoid. * **Tzanck Smear:** Shows "Acantholytic cells" (Tzanck cells)—large, round keratinocytes with hyperchromatic nuclei—in Pemphigus. * **Immunofluorescence:** Pemphigus shows a **"fishnet" or "reticular"** pattern of IgG, while Bullous Pemphigoid shows a **linear** pattern at the dermo-epidermal junction. * **Other Acantholytic Disorders:** Hailey-Hailey disease (familial benign pemphigus) and Darier disease.

Q: What cell type is described as acantholytic?

Keratinocyte. **Explanation:** **Acantholysis** is the hallmark pathological process in immunobullous diseases like Pemphigus Vulgaris. It refers to the loss of intercellular connections (desmosomes) between **keratinocytes**, resulting in the formation of intraepidermal clefts and blisters. 1. **Why Keratinocyte is correct:** Keratinocytes are the primary structural cells of the epidermis. They are held together by desmosomes. In acantholysis, autoantibodies (e.g., anti-desmoglein) attack these connections, causing the keratinocytes to detach from one another. These detached cells become rounded, have hyperchromatic nuclei, and are known as **Tzanck cells**. 2. **Why other options are incorrect:** * **Melanocytes:** These are pigment-producing cells located in the basal layer. While they can be involved in disorders like vitiligo or melanoma, they do not undergo acantholysis. * **Neutrophils & Monocytes:** These are inflammatory white blood cells. While they may infiltrate the skin during infection or inflammation (e.g., subcorneal pustular dermatosis), they are not the structural cells that detach to form acantholytic blisters. **High-Yield Clinical Pearls for NEET-PG:** * **Tzanck Smear:** A rapid bedside test where a scraping from the base of a vesicle is stained (Giemsa/Wright) to look for rounded, acantholytic keratinocytes. * **Nikolsky Sign:** Positive in diseases with acantholysis (like Pemphigus), where firm sliding pressure on normal-looking skin causes exfoliation. * **Differential Diagnosis:** Acantholysis is "primary" in Pemphigus and "secondary" in infections like Herpes Simplex (viral cytopathic effect) or Impetigo (staphylococcal exfoliatin toxin).

Q: What is described by a subepithelial bulla?

Bullous pemphigoid. ### Explanation The level of split (cleavage) within the skin layers is the most critical diagnostic feature in blistering diseases. **1. Why Bullous Pemphigoid is correct:** Bullous pemphigoid is a **subepidermal (subepithelial)** autoimmune blistering disease. It is caused by IgG autoantibodies directed against **BP180 (Type XVII collagen)** and **BP230** located in the hemidesmosomes of the dermo-epidermal junction. Because the entire thickness of the epidermis forms the roof of the blister, the bullae are **tense**, large, and do not rupture easily (Negative Nikolsky sign). **2. Why the other options are incorrect:** * **Pemphigus (Vulgaris/Foliaceus):** These are **intraepidermal** diseases. Antibodies target desmogleins (desmosomes), leading to loss of cell-to-cell adhesion (acantholysis). This results in flaccid bullae that rupture easily. * **Hailey-Hailey Disease:** Also known as Familial Benign Pemphigus, it is a genetic defect in the calcium pump (ATP2C1). It results in **intraepidermal** acantholysis, often described as a "dilapidated brick wall" appearance on histology. * **Herpes Zoster:** Viral infections like Herpes cause **intraepidermal** vesicles due to ballooning degeneration and acantholysis of keratinocytes. **3. NEET-PG High-Yield Pearls:** * **Subepidermal Blisters (Tense):** Bullous Pemphigoid, Dermatitis Herpetiformis (IgA at papillary tips), Epidermolysis Bullosa Acquisita, Cicatricial Pemphigoid. * **Intraepidermal Blisters (Flaccid):** Pemphigus group, Staphylococcal Scalded Skin Syndrome (SSSS). * **Immunofluorescence (IF):** Bullous Pemphigoid shows **linear** IgG and C3 deposits along the basement membrane zone, whereas Pemphigus shows a **"fishnet" or "lace-like"** pattern.

Q: A 45-year-old female presented with recurrent oral erosions followed by multiple flaccid bullae on the trunk and extremities. A Tzanck smear showed acantholytic cells, and direct immunofluorescence demonstrated intercellular IgG deposits in the epidermis. What is the most probable diagnosis?

Pemphigus vulgaris. **Explanation:** The clinical presentation and diagnostic findings are classic for **Pemphigus Vulgaris (PV)**. 1. **Why Pemphigus Vulgaris is correct:** PV is an autoimmune blistering disease caused by IgG antibodies against **Desmoglein 3** (and sometimes Desmoglein 1). * **Clinical:** It typically begins with **recurrent oral erosions** (mucosa first) followed by **flaccid bullae** on the skin that rupture easily (positive Nikolsky sign). * **Cytology:** A Tzanck smear reveals **acantholytic cells** (Tzanck cells)—keratinocytes that have lost their intercellular connections. * **Immunofluorescence (DIF):** Shows a characteristic **"fishnet" or "chicken-wire" pattern** due to intercellular IgG and C3 deposits throughout the epidermis. 2. **Why other options are incorrect:** * **Bullous Pemphigoid:** Presents with **tense bullae** in older patients. DIF shows **linear** IgG/C3 deposits along the basement membrane zone (subepidermal), not intercellular. * **Stevens-Johnson Syndrome:** An acute hypersensitivity reaction characterized by targetoid lesions and extensive epidermal necrolysis. It is not an acantholytic process and would not show the fishnet DIF pattern. * **Herpes Simplex 1:** While it shows acantholytic cells on Tzanck smear, it also features **multinucleated giant cells** and viral inclusions. It presents as grouped vesicles on an erythematous base, not generalized flaccid bullae. **High-Yield Pearls for NEET-PG:** * **Nikolsky Sign & Bulla Spread Sign (Asboe-Hansen):** Both are **positive** in Pemphigus Vulgaris but negative in Bullous Pemphigoid. * **Row of Tombstones:** Histopathology shows suprabasal clefting with a single layer of basal cells remaining attached to the basement membrane. * **Antigen:** Desmoglein 3 (Mucosal-dominant); Desmoglein 1 + 3 (Mucocutaneous).

Q: A patient presents with bullous lesions on the face, axilla, and chest, which initially appeared in the mouth. The lesions are described as round and oval with serous fluid and appear 'flabby.' Lateral spread of fluid is observed upon applying pressure. Given a clinical diagnosis of pemphigus vulgaris (PV), what is the typical age of onset for this condition?

40-60 years of age. ### Explanation **1. Why Option D is Correct:** Pemphigus Vulgaris (PV) is an autoimmune blistering disease characterized by the production of IgG antibodies against **Desmoglein 3** (and sometimes Desmoglein 1). These antibodies cause acantholysis (loss of cell-to-cell adhesion). Epidemiologically, PV typically manifests in middle-aged adults, with the peak incidence occurring between the **4th and 6th decades of life (40–60 years)**. It shows no significant gender predilection. **2. Why Other Options are Incorrect:** * **Options A & B (<20 years):** While "Pemphigus Juvenilis" exists, it is extremely rare. Bullous diseases in children are more likely to be Linear IgA Bullous Dermatosis or Bullous Impetigo. * **Option C (20–40 years):** While cases can occur in this range, it is less common than the 40–60 age bracket. Conditions like Dermatitis Herpetiformis often present in this younger adult demographic. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Initial Site:** Oral mucosa is the first site of involvement in 50–70% of cases ("First to come, last to go"). * **The Blister:** Because the split is intraepidermal (suprabasal), the bullae are **flaccid/flabby** and rupture easily, leaving painful erosions. * **Nikolsky Sign:** Positive (perilesional skin shears off with lateral pressure). * **Asboe-Hansen Sign (Indirect Nikolsky/Bulla Spread Sign):** Positive (lateral extension of the blister when pressure is applied to the roof). * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei and a peripheral halo of cytoplasm (condensed at the rim). * **Immunofluorescence (DIF):** Shows a characteristic **"Fish-net" or "Lace-like"** pattern of IgG and C3 deposits in the intercellular spaces.

Q: Subepidermal bullae are seen in which of the following conditions?

Bullous pemphigoid. **Explanation:** The level of split (cleavage) within the skin layers is the most critical diagnostic feature in blistering diseases. **Correct Option: C. Bullous pemphigoid** Bullous pemphigoid is an autoimmune condition characterized by **subepidermal bullae**. The pathology involves IgG autoantibodies targeting **BP180 (Type XVII collagen)** and **BP230** within the hemidesmosomes. This leads to the detachment of the entire epidermis from the dermis at the level of the **lamina lucida**. Because the "roof" of the blister consists of the full thickness of the epidermis, the bullae are characteristically **tense** and less likely to rupture compared to intraepidermal blisters. **Incorrect Options:** * **A. Pemphigus vulgaris:** This is an **intraepidermal** blistering disease. Autoantibodies (anti-Desmoglein 3) cause loss of cell-to-cell adhesion (acantholysis) just above the basal layer, resulting in **suprabasal** blisters. * **B. Darier’s disease:** This is a keratinization disorder caused by a mutation in the ATP2A2 gene. It presents with **suprabasal acantholysis** and dyskeratosis (corps ronds and grains), not subepidermal cleavage. * **C. HSV infection:** Viral infections typically cause **intraepidermal** vesicles due to ballooning degeneration and reticular degeneration of keratinocytes. **NEET-PG High-Yield Pearls:** * **Tense Bullae:** Suggests subepidermal (e.g., Bullous pemphigoid, Dermatitis herpetiformis). * **Flaccid Bullae/Nikolsky Sign (+):** Suggests intraepidermal (e.g., Pemphigus vulgaris, SJS/TEN). * **Direct Immunofluorescence (DIF):** Bullous pemphigoid shows **linear IgG and C3** deposits along the basement membrane zone (BMZ). * **Salt-split skin technique:** In Bullous pemphigoid, the antibodies deposit on the **roof** (epidermal side) of the split.

Q: Simplex type of Epidermolysis Bullosa involves mutations in which of the following?

Keratin 5. **Explanation:** Epidermolysis Bullosa (EB) is a group of genetic mechanobullous disorders characterized by skin fragility and blister formation following minor trauma. The classification is based on the **level of cleavage** within the skin layers. **1. Why Keratin 5 is correct:** **EB Simplex (EBS)** is the most common type. The cleavage occurs at the **intra-epidermal level**, specifically within the basal keratinocytes. It is primarily caused by autosomal dominant mutations in **Keratin 5 and Keratin 14**. These keratins form the intermediate filament cytoskeleton that provides structural integrity to basal cells; their defect leads to cytolysis and superficial blistering. **2. Analysis of Incorrect Options:** * **B. Lamina lucida:** This is the site of cleavage for **Junctional EB**. The primary defect involves **Laminin 332** (formerly Laminin 5). * **C. Type VII collagen:** This protein forms anchoring fibrils in the sub-lamina densa. Mutations here lead to **Dystrophic EB**, where cleavage occurs below the basement membrane, leading to significant scarring and milia. * **D. Dystrophin:** This protein is associated with Duchenne Muscular Dystrophy, not blistering skin diseases. (Note: *Plec-1* mutations cause EB with Muscular Dystrophy, but the protein involved is Plectin). **Clinical Pearls for NEET-PG:** * **EBS (Simplex):** Most common, heals *without* scarring. * **JEB (Junctional):** Most severe (Herlitz type), involves exuberant granulation tissue. * **DEB (Dystrophic):** Heals *with* scarring, milia formation, and "mitten-hand" deformities (pseudosyndactyly). * **Kindler Syndrome:** A rare mixed type where cleavage occurs at multiple levels.

Question 1

What is true about erythema multiforme?

Accepted Answer

All of the above.

Answer

Target lesions are characteristic.

Answer

Hemorrhagic crusts may form on lips.

Answer

Lesions resolve over 3 to 6 weeks.

Question 2

A patient presents with tense bullae on an erythematous base. What is seen on histopathological examination?

Accepted Answer

Subepidermal split

Answer

Subcorneal split

Answer

Fishnet pattern

Answer

Row of tombstone appearance

Question 3

What is the commonest and rarest variety of Pemphigus?

Accepted Answer

Pemphigus vulgaris/Pemphigus vegetans

Answer

Pemphigus vegetans/Pemphigus vulgaris

Answer

Pemphigus foliaceus/Pemphigus erythematosus

Answer

Pemphigus erythematosus/Pemphigus foliaceus

Question 4

Which of the following disorders is associated with acantholysis?

Accepted Answer

Pemphigus vulgaris

Answer

Pemphigoid

Answer

Erythema multiforme

Answer

Dermatitis herpetiformis

Question 5

What cell type is described as acantholytic?

Accepted Answer

Keratinocyte

Answer

Melanocyte

Answer

Neutrophil

Answer

Monocyte

Question 6

What is described by a subepithelial bulla?

Accepted Answer

Bullous pemphigoid

Answer

Herpes zoster

Answer

Pemphigus

Answer

Hailey Hailey disease

Question 7

A 45-year-old female presented with recurrent oral erosions followed by multiple flaccid bullae on the trunk and extremities. A Tzanck smear showed acantholytic cells, and direct immunofluorescence demonstrated intercellular IgG deposits in the epidermis. What is the most probable diagnosis?

Accepted Answer

Pemphigus vulgaris

Answer

Bullous Pemphigoid

Answer

Stevens-Johnson syndrome

Answer

Herpes simplex 1 infection

Question 8

A patient presents with bullous lesions on the face, axilla, and chest, which initially appeared in the mouth. The lesions are described as round and oval with serous fluid and appear 'flabby.' Lateral spread of fluid is observed upon applying pressure. Given a clinical diagnosis of pemphigus vulgaris (PV), what is the typical age of onset for this condition?

Accepted Answer

40-60 years of age

Answer

Under 10 years of age

Answer

10-20 years of age

Answer

20-40 years of age

Question 9

Subepidermal bullae are seen in which of the following conditions?

Accepted Answer

Bullous pemphigoid

Answer

Pemphigus vulgaris

Answer

Darier's disease

Answer

Herpes simplex virus (HSV) infection

Question 10

Simplex type of Epidermolysis Bullosa involves mutations in which of the following?

Accepted Answer

Keratin 5

Answer

Lamina lucida

Answer

Type VII collagen

Answer

Dystrophin

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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