Autoimmune Skin Diseases Practice Questions

Q: A female patient presents with tense bullae on an erythematous base. What is the most likely diagnosis?

Bullous pemphigoid. ### Explanation **Correct Answer: B. Bullous pemphigoid** **Why it is correct:** The clinical hallmark of **Bullous Pemphigoid (BP)** is the presence of **tense bullae** on an erythematous or eczematous base. This occurs because BP is a **subepidermal** blistering disease. The autoantibodies (anti-BP180 and anti-BP230) target the hemidesmosomes at the dermo-epidermal junction. Because the entire thickness of the epidermis forms the roof of the blister, it is structurally strong and "tense," making it less likely to rupture easily. **Why the other options are incorrect:** * **Pemphigus vulgaris (C):** This is an **intraepidermal** disease (acantholysis). Because the blister roof is very thin (only the upper layers of the epidermis), the bullae are **flaccid** and rupture easily, often presenting as erosions. * **Pemphigus erythematosus (A) and Pemphigus vegetans (D):** These are variants of the Pemphigus group. Like Pemphigus vulgaris, they involve intraepidermal splitting and do not typically present with the classic "tense" bullae seen in subepidermal pathologies. **NEET-PG High-Yield Pearls:** * **Nikolsky Sign:** Negative in Bullous Pemphigoid; Positive in Pemphigus Vulgaris. * **Direct Immunofluorescence (DIF):** Shows **linear** IgG and C3 deposits along the basement membrane zone in BP. (In Pemphigus, it shows a "fish-net" or "lace-like" pattern). * **Demographics:** BP typically affects the elderly (60+ years), whereas Pemphigus often affects middle-aged adults (40–60 years). * **Mucosal involvement:** Common and severe in Pemphigus vulgaris; rare and usually mild in Bullous Pemphigoid.

Q: Blistering in Bullous pemphigoid is because of antibodies against which of the following antigens?

BPAG2. **Explanation:** **Bullous Pemphigoid (BP)** is an autoimmune subepidermal blistering disorder primarily affecting the elderly. The pathogenesis involves the formation of IgG autoantibodies against components of the **hemidesmosome**, which anchors the basal layer of the epidermis to the basement membrane. 1. **Why BPAG2 is correct:** The primary pathogenic target in BP is **BPAG2 (Bullous Pemphigoid Antigen 2)**, also known as **Type XVII Collagen**. It is a transmembrane protein. Antibodies against the extracellular **NC16A domain** of BPAG2 are responsible for the subepidermal split and blister formation. 2. **Why other options are incorrect:** * **BPAG1 (BP230):** This is an intracellular plakin family protein. While antibodies to BPAG1 are found in BP, they are generally considered secondary and less pathogenic than anti-BPAG2. * **Filaggrin:** This protein aggregates keratin filaments in the stratum corneum. Mutations in the filaggrin gene (*FLG*) are associated with **Ichthyosis vulgaris** and **Atopic Dermatitis**, not blistering diseases. * **Keratin 5:** Mutations in Keratin 5 (and Keratin 14) lead to **Epidermolysis Bullosa Simplex**, where blistering occurs due to mechanical fragility within the basal layer. **High-Yield Clinical Pearls for NEET-PG:** * **Immunofluorescence:** Direct Immunofluorescence (DIF) shows **linear IgG and C3 deposits** along the basement membrane zone. * **Clinical Feature:** Characterized by **tense bullae** on an erythematous base, often preceded by a chronic pruritic eczematous phase. * **Histopathology:** Subepidermal blister with a prominent **eosinophilic** infiltrate. * **Mnemonic:** **B**ullous = **B**elow (Subepidermal) and **B**PAG**2** (Transmembrane/Pathogenic).

Q: Which of the following conditions is associated with pyoderma gangrenosum?

Non-Hodgkin's Lymphoma. **Explanation:** Pyoderma Gangrenosum (PG) is a rare, non-infectious neutrophilic dermatosis characterized by painful, rapidly progressing necrotic ulcers with undermined violaceous borders. It is strongly associated with systemic diseases in approximately 50% of cases. **1. Why Non-Hodgkin’s Lymphoma (NHL) is correct:** While the most common hematologic associations with PG are **Acute Myeloid Leukemia (AML)** and **Monoclonal Gammopathy (IgA)**, among the lymphomas, **Non-Hodgkin’s Lymphoma** is the classically recognized association. The underlying pathophysiology involves a state of "pathergy" and immune dysregulation often triggered by the paraneoplastic effects of the underlying malignancy. **2. Analysis of Incorrect Options:** * **Hodgkin’s Lymphoma:** While HL is associated with various paraneoplastic skin conditions (like Ichthyosis acquisita or Pruritus), it is significantly less commonly linked to Pyoderma Gangrenosum compared to NHL. * **Mantle Cell Lymphoma & MALToma:** These are specific subtypes of B-cell NHL. While they could theoretically cause PG, the question asks for the broader category. In medical entrance exams, "Non-Hodgkin's Lymphoma" is the standard high-yield association taught for PG. **3. Clinical Pearls for NEET-PG:** * **Most Common Association:** Inflammatory Bowel Disease (IBD), specifically **Ulcerative Colitis** (more common than Crohn’s). * **Other Associations:** Rheumatoid Arthritis, Seronegative Spondyloarthropathies, and Myelodysplastic Syndrome (MDS). * **Pathergy Phenomenon:** Development of new lesions at sites of minor trauma (also seen in Behçet’s disease and Sweet Syndrome). * **Treatment of Choice:** Systemic Corticosteroids or Cyclosporine. * **Histopathology:** Shows a dense neutrophilic infiltrate (neutrophilic dermatosis).

Q: Subepithelial vesicles are characteristic of all of the following conditions EXCEPT?

Pemphigus. **Explanation:** The level of blister formation is the most critical diagnostic feature in immunobullous disorders. Blisters are classified as either **intraepidermal** (within the epidermis) or **subepidermal** (below the epidermis/dermo-epidermal junction). **Why Pemphigus is the Correct Answer:** Pemphigus (including Pemphigus Vulgaris and Pemphigus Foliaceus) is characterized by **intraepidermal** vesicles. This occurs due to **acantholysis**—the loss of intercellular connections (desmosomes) between keratinocytes caused by IgG antibodies against Desmogleins. Because the split occurs within the cellular layer, the resulting blisters are thin-walled, flaccid, and rupture easily (positive Nikolsky sign). **Analysis of Incorrect Options (Subepithelial/Subepidermal Conditions):** All other options involve pathology at the dermo-epidermal junction (DEJ), leading to a split below the epithelium: * **Bullous Pemphigoid:** Caused by antibodies against BP180 and BP230 in the hemidesmosomes. The split is subepidermal, resulting in tense bullae. * **Cicatricial Pemphigoid (Mucous Membrane Pemphigoid):** A subepithelial blistering disease primarily affecting mucous membranes, often leading to scarring. * **Epidermolysis Bullosa Acquisita (EBA):** Characterized by antibodies against Type VII collagen in the anchoring fibrils, located below the lamina densa (subepithelial). **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in Pemphigus (intraepidermal); Negative in Bullous Pemphigoid (subepidermal). * **Tzanck Smear:** Shows "Acantholytic cells" (Tzanck cells) in Pemphigus; absent in subepidermal diseases. * **Dermatitis Herpetiformis:** Another high-yield subepidermal condition associated with Celiac disease and IgA deposits in dermal papillae. * **Mnemonic:** "Pemphig**u**s is **U**p" (Intraepidermal); "Pemphigoi**d** is **D**eep" (Subepidermal).

Q: The 'shawl sign' is a clinical finding associated with which of the following conditions?

Dermatomyositis. **Explanation:** **Dermatomyositis** is an idiopathic inflammatory myopathy characterized by proximal muscle weakness and distinctive cutaneous manifestations. The **Shawl sign** refers to a persistent, confluent, erythematous to violaceous macular rash involving the upper back, posterior neck, and shoulders (resembling the distribution of a shawl). This is a photosensitive eruption and is a classic diagnostic clue for the disease. **Analysis of Options:** * **Dermatomyositis (Correct):** Along with the Shawl sign, other pathognomonic features include **Gottron papules** (violaceous papules over bony prominences/knuckles), **Heliotrope rash** (periorbital violaceous edema), and the **V-sign** (rash on the anterior chest). * **Psoriasis:** Characterized by well-demarcated erythematous plaques with silvery-white scales, typically on extensors. It is associated with the Auspitz sign and Koebner phenomenon, not the Shawl sign. * **Sunburn:** While sunburn causes erythema in sun-exposed areas, the Shawl sign is a specific chronic inflammatory marker of dermatomyositis, often appearing even with minimal UV exposure and persisting longer than a simple burn. * **Skin Cancer:** While UV radiation is a risk factor for both, skin cancers (like BCC or SCC) present as localized nodules or non-healing ulcers rather than a diffuse, symmetrical "shawl-like" macular eruption. **High-Yield Clinical Pearls for NEET-PG:** * **Holster sign:** Erythema on the lateral aspect of the thighs (another specific sign of Dermatomyositis). * **Mechanic’s Hands:** Hyperkeratosis and fissuring of the palms/fingers; often associated with **Anti-Jo-1 antibodies** and interstitial lung disease. * **Malignancy Link:** Dermatomyositis in adults is a paraneoplastic syndrome; always screen for underlying visceral malignancies (e.g., ovarian, lung, or GI cancers).

Q: A 60-year-old man presented with itchy tense blisters on normal-looking skin and urticarial rash. What is the primary investigation for the diagnosis?

Direct immunofluorescence. **Explanation:** The clinical presentation of **tense blisters** on a 60-year-old patient, associated with an **urticarial rash** and intense itching, is classic for **Bullous Pemphigoid (BP)**. In BP, the split occurs at the subepidermal level (basement membrane zone), leading to strong, tense roofs that do not rupture easily. **Why Direct Immunofluorescence (DIF) is the Correct Answer:** DIF is the **gold standard** for diagnosing autoimmune blistering diseases. In Bullous Pemphigoid, DIF of perilesional skin typically shows a **linear deposition of IgG and C3 along the basement membrane zone (BMZ)**. This confirms the presence of autoantibodies (anti-BP180 and anti-BP230) bound to the tissue, providing a definitive diagnosis. **Analysis of Incorrect Options:** * **Indirect Immunofluorescence (IIF):** This tests the patient’s **serum** for circulating antibodies. While useful for monitoring disease activity, it is less sensitive than DIF for primary diagnosis. * **Histopathology:** While a biopsy would show a subepidermal cleft with eosinophils, it cannot distinguish BP from other subepidermal diseases (like Epidermolysis Bullosa Acquisita) as reliably as DIF. * **Cytopathology (Tzanck Smear):** This is used to identify acantholytic cells (Tzanck cells) in **Pemphigus Vulgaris** or multinucleated giant cells in Herpes. It is not useful for subepidermal blisters like BP. **High-Yield Clinical Pearls for NEET-PG:** * **Bullous Pemphigoid:** Tense blisters, subepidermal, negative Nikolsky sign, linear IgG/C3 on DIF. * **Pemphigus Vulgaris:** Flaccid blisters, intraepidermal, positive Nikolsky sign, "row of tombstones" on histology, "fishnet/lace-like" pattern on DIF. * **Salt-split skin technique:** A specialized IIF used to differentiate BP (roof pattern) from EBA (floor pattern).

Q: Scleredema is associated with which of the following conditions?

Diabetes. **Explanation:** **Scleredema (Scleredema of Buschke)** is a rare sclerodermiform condition characterized by diffuse, non-pitting induration of the skin, primarily affecting the neck, shoulders, and upper back. **Why Diabetes is the Correct Answer:** Scleredema is classically associated with three clinical scenarios, the most common being **Diabetes Mellitus (Type 2)**. In diabetic patients (Scleredema Diabeticorum), the condition is typically seen in middle-aged, obese males with long-standing, poorly controlled glycemia. The underlying pathophysiology involves the non-enzymatic glycosylation of collagen and an increase in collagen synthesis by fibroblasts, leading to a thickened dermis with heavy deposits of acid mucopolysaccharides (mucin). **Analysis of Incorrect Options:** * **A. Progressive Systemic Sclerosis (PSS):** While both involve skin thickening, PSS (Scleroderma) typically starts distally (sclerodactyly), involves Raynaud’s phenomenon, and shows loss of skin appendages—features absent in Scleredema. * **B. Leprosy:** Leprosy presents with anesthetic patches, nerve thickening, or nodules (lepromas), not diffuse woody induration of the trunk. * **C. Hypothyroidism:** This is associated with **Generalized Myxedema**, where skin is dry, pale, and waxy due to dermal mucin, but it does not present with the specific "woody" induration of the upper back seen in Scleredema. **High-Yield Clinical Pearls for NEET-PG:** * **Three Types of Scleredema:** 1. **Type 1:** Follows an acute febrile illness (usually Streptococcal). 2. **Type 2:** Associated with Monoclonal Gammopathy (Multiple Myeloma). 3. **Type 3:** Associated with Diabetes Mellitus (most persistent form). * **Histopathology:** Significant dermal thickening with large collagen bundles separated by clear spaces containing **Hyaluronic acid** (Mucin). * **Clinical Sign:** The "Peau d’orange" appearance may be seen on the affected skin.

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

Pemphigus vulgaris. **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.

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

Pemphigus. **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).

Q: Histological appearance of scleroderma includes all except?

Extensive fibrosis of upper 1/3 of the dermis. **Explanation:** The hallmark of **Scleroderma (Systemic Sclerosis)** is the excessive deposition of collagen throughout the dermis. However, the fibrosis is not limited to the upper 1/3; instead, it typically involves the **entire thickness of the dermis** and often extends into the subcutaneous fat. * **Why Option A is the correct answer:** In scleroderma, fibrosis is **pan-dermal**. The collagen bundles become thick, packed, and oriented parallel to the epidermis. Restricting the description to only the "upper 1/3" is histologically inaccurate as the disease process characteristically involves the deep dermis and leads to the loss of the dermo-hypodermal interface. * **Why other options are incorrect:** * **Decreased adnexal structures (B):** As collagen bundles expand and pack tightly, they "choke" or replace normal skin structures. This leads to the atrophy and eventual disappearance of hair follicles and sweat glands. * **Homogenization of collagen (C):** Under the microscope, the collagen bundles lose their distinct outlines and appear as a solid, eosinophilic (pink), glassy mass. * **Increased dermal thickness (D):** The massive deposition of Type I and Type III collagen significantly increases the overall depth of the dermal layer, which clinically manifests as skin tightening and induration. **NEET-PG High-Yield Pearls:** 1. **Square-off Sign:** On biopsy, the specimen often appears rectangular or "squared-off" because the tissue is so rigid it does not curl. 2. **Entrapment of Eccrine Glands:** A classic sign where sweat glands appear "trapped" in the middle of dense dermal collagen rather than sitting at the dermo-hypodermal junction. 3. **CD34+ Fibroblasts:** There is a characteristic **loss** of CD34+ dendritic interstitial cells in the affected dermis. 4. **Clinical Triad:** Vascular injury (Raynaud’s), Autoimmunity (ANA, Scl-70, Anti-centromere), and Progressive Fibrosis.

Question 1

A female patient presents with tense bullae on an erythematous base. What is the most likely diagnosis?

Accepted Answer

Bullous pemphigoid

Answer

Pemphigus erythematosus

Answer

Pemphigus vulgaris

Answer

Pemphigus vegetans

Question 2

Blistering in Bullous pemphigoid is because of antibodies against which of the following antigens?

Accepted Answer

BPAG2

Answer

BPAG1

Answer

Filaggrin

Answer

Keratin 5

Question 3

Which of the following conditions is associated with pyoderma gangrenosum?

Accepted Answer

Non-Hodgkin's Lymphoma

Answer

Hodgkin's Lymphoma

Answer

Mantle cell Lymphoma

Answer

MALToma

Question 4

Subepithelial vesicles are characteristic of all of the following conditions EXCEPT?

Accepted Answer

Pemphigus

Answer

Bullous pemphigoid

Answer

Cicatricial pemphigoid

Answer

Epidermolysis bullosa acquisita

Question 5

The 'shawl sign' is a clinical finding associated with which of the following conditions?

Accepted Answer

Dermatomyositis

Answer

Psoriasis

Answer

Sunburn

Answer

Skin Cancer

Question 6

A 60-year-old man presented with itchy tense blisters on normal-looking skin and urticarial rash. What is the primary investigation for the diagnosis?

Accepted Answer

Direct immunofluorescence

Answer

Indirect immunofluorescence

Answer

Histopathology

Answer

Cytopathology

Question 7

Scleredema is associated with which of the following conditions?

Accepted Answer

Diabetes

Answer

Progressive systemic sclerosis

Answer

Leprosy

Answer

Hypothyroidism

Question 8

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

Accepted Answer

Pemphigus vulgaris

Answer

Herpes gestationalis

Answer

Bullous pemphigoid

Answer

Herpes simplex

Question 9

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

Accepted Answer

Pemphigus

Answer

Irritant dermatitis

Answer

Pemphigoid

Answer

Herpes zoster

Question 10

Histological appearance of scleroderma includes all except?

Accepted Answer

Extensive fibrosis of upper 1/3 of the dermis

Answer

Decreased adnexal structures

Answer

Homogenization of collagen

Answer

Increased dermal thickness

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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