Autoimmune Skin Diseases Practice Questions

Q: Acantholysis, resulting from desmosome weakening by autoantibodies directed against the protein desmoglein, is the disease mechanism attributed to which of the following?

Pemphigus vulgaris. ### Explanation **Correct Answer: C. Pemphigus vulgaris** **Mechanism:** Pemphigus vulgaris (PV) is an autoimmune blistering disease characterized by **acantholysis**—the loss of cell-to-cell adhesion between keratinocytes. This occurs because IgG autoantibodies target **Desmoglein 3** (and sometimes Desmoglein 1), which are critical transmembrane glycoproteins of the **desmosomes**. When these desmosomes are disrupted, keratinocytes detach from one another, leading to the formation of intraepidermal blisters. Because the basal layer remains attached to the basement membrane via hemidesmosomes, it creates the classic "tombstone appearance" on histology. **Why other options are incorrect:** * **A. Epidermolysis bullosa:** This is a group of *genetic* (not autoimmune) mechanobullous disorders caused by mutations in structural proteins like keratins (EB Simplex) or laminin/collagen (Junctional/Dystrophic EB). * **B. Mucous membrane pemphigoid:** This is an autoimmune disease, but the antibodies target the **basement membrane zone** (specifically BP180 or laminin 332) in hemidesmosomes, leading to *subepidermal* blisters, not acantholysis. * **D. Herpes simplex infections:** While HSV causes intraepidermal vesicles, the mechanism is viral-induced **ballooning degeneration** and cytolysis, not an autoimmune attack on desmogleins. **High-Yield NEET-PG Pearls:** * **Nikolsky Sign:** Positive in Pemphigus vulgaris (due to acantholysis); negative in Bullous Pemphigoid. * **Tzanck Smear:** Shows rounded, detached keratinocytes with hyperchromatic nuclei called **Acantholytic or Tzanck cells**. * **Direct Immunofluorescence (DIF):** Shows a characteristic **"fishnet" or "lace-like"** pattern of IgG/C3 deposits. * **Clinical Presentation:** Often starts with painful oral ulcers before progressing to flaccid skin bullae.

Q: A butterfly rash characteristically spares which of the following facial areas?

Nasolabial fold. **Explanation:** The **butterfly rash** (malar rash) is the classic cutaneous manifestation of **Systemic Lupus Erythematosus (SLE)**. It is characterized by an erythematous, sometimes edematous, eruption over the malar eminence. **1. Why Nasolabial Folds are Spared:** The hallmark feature that distinguishes the butterfly rash of SLE from other facial rashes (like seborrheic dermatitis or rosacea) is the **sparing of the nasolabial folds**. This occurs because the rash is primarily **photosensitive**; the deep anatomical contour of the nasolabial fold is relatively shielded from direct UV radiation, preventing the inflammatory cascade in that specific area. **2. Analysis of Incorrect Options:** * **Cheeks (A):** These are the primary site of the rash (malar distribution). * **Lower eyelids (C):** While the rash can approach the eyes, it typically involves the malar area just below the lids; however, the nasolabial fold is the *characteristic* spared site mentioned in textbooks. * **Bridge of nose (D):** The rash characteristically connects across the bridge of the nose, completing the "butterfly" shape. **High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis:** In **Dermatomyositis**, the rash (Heliotrope rash) involves the eyelids and **does not** spare the nasolabial folds. In **Rosacea**, there are often associated pustules and telangiectasia, which are absent in SLE. * **Systemic Association:** A malar rash is one of the 11 ACR criteria for diagnosing SLE. * **Histopathology:** SLE shows vacuolar degeneration of the basal layer and a "lupus band" (IgG/C3 deposits) at the dermo-epidermal junction.

Q: Which of the following is true regarding lichen planus?

Can undergo malignant change. **Lichen Planus (LP)** is a chronic, inflammatory, T-cell-mediated autoimmune condition affecting the skin, hair, nails, and mucous membranes. ### **Explanation of the Correct Option** **A. Can undergo malignant change:** Chronic erosive or hypertrophic variants of Lichen Planus, particularly **Oral Lichen Planus (OLP)** and **Lichen Planus Hypertrophicus (LPH)**, are considered premalignant conditions. Long-standing inflammation can lead to the development of **Squamous Cell Carcinoma (SCC)**. The risk is estimated at approximately 1% for oral lesions. ### **Explanation of Incorrect Options** * **B. Treated only by medication:** While topical/systemic steroids and retinoids are the mainstays, treatment also includes lifestyle modifications (avoiding Koebnerization) and phototherapy (PUVA/NB-UVB). * **C. Must be excised:** LP is an inflammatory condition, not a primary surgical one. Excision is generally avoided because of the **Koebner phenomenon** (new lesions appearing at the site of trauma/surgery). Surgery is reserved only for biopsy or if malignancy is suspected. * **D. Is an idiosyncrasy reaction:** LP is an autoimmune process. "Idiosyncrasy" usually refers to unpredictable drug reactions (e.g., Lichenoid drug eruptions), but classic LP is idiopathic or associated with Hepatitis C. ### **High-Yield NEET-PG Pearls** * **6 P’s of LP:** Planar (flat-topped), Purple (violaceous), Polygonal, Pruritic, Papules, and Plaques. * **Wickham Striae:** White reticular patterns on the surface of papules (due to focal hypergranulosis). * **Histopathology:** Characteristic "saw-tooth" appearance of rete ridges, Max-Joseph spaces, and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Civatte Bodies:** Degenerating keratinocytes (colloid bodies) in the lower epidermis. * **Koebner Phenomenon:** Also seen in Psoriasis and Vitiligo.

Q: "En coup de sabre" is seen in:

Scleroderma. **Explanation:** **En coup de sabre** is a classic clinical presentation of **Linear Scleroderma**, a subtype of localized scleroderma (morphea). The term is French for "cut of the sword," describing a linear, indented scar-like lesion that typically occurs on the forehead or scalp. 1. **Why Scleroderma is correct:** In linear scleroderma, there is localized inflammation followed by fibrosis and atrophy of the skin, subcutaneous tissue, and sometimes the underlying muscle and bone. When this occurs on the frontoparietal region, it creates a sunken, ivory-colored furrow that mimics a sword wound. It can be associated with hemi-facial atrophy (Parry-Romberg Syndrome). 2. **Why other options are incorrect:** * **Syphilis:** Presents with features like chancre (primary), condyloma lata, or maculopapular rashes (secondary), and gummas (tertiary), but not linear atrophy. * **Leprosy:** Characterized by hypopigmented patches with loss of sensation or thickened nerves, not linear fibrotic furrows. * **Scabies:** A parasitic infestation presenting with intense nocturnal pruritus and "burrows" (short, wavy lines), primarily in finger webs and flexures. **High-Yield Clinical Pearls for NEET-PG:** * **Morphea:** Localized scleroderma that lacks systemic involvement (no sclerodactyly or Raynaud’s). * **Parry-Romberg Syndrome:** Progressive facial hemi-atrophy often seen in conjunction with *en coup de sabre*. * **Histology:** Look for "squared-off" biopsy specimens due to dense collagen deposition and loss of periappecular fat. * **Treatment:** Potent topical steroids or calcineurin inhibitors for limited disease; methotrexate for deep or progressive lesions.

Q: Which of the following is a dermatological manifestation of Inflammatory Bowel Disease?

Pyoderma gangrenosum. **Explanation:** **Pyoderma gangrenosum (PG)** is a classic cutaneous manifestation of **Inflammatory Bowel Disease (IBD)**, particularly Ulcerative Colitis. It is a neutrophilic dermatosis characterized by a rapidly enlarging, painful ulcer with a characteristic "undermined" violaceous border. The underlying medical concept is an autoinflammatory response where neutrophils infiltrate the dermis. Notably, the clinical course of PG does not always correlate with the activity of the bowel disease. **Analysis of Incorrect Options:** * **B. Necrolytic migratory erythema:** This is the pathognomonic skin finding associated with a **Glucagonoma** (an alpha-cell pancreatic tumor). It presents as erythematous, scaly plaques with central clearing, typically in the intertriginous areas. * **C. Impetigo:** This is a common superficial **bacterial infection** (usually *Staph. aureus* or *Strep. pyogenes*) characterized by honey-colored crusts. It is not an autoimmune or systemic manifestation of IBD. * **D. Psoriasis:** While there is a known genetic and inflammatory overlap between Psoriasis and IBD (both involve the IL-23/IL-17 pathway), Psoriasis is considered a separate comorbid condition rather than a direct dermatological manifestation of IBD. **High-Yield Clinical Pearls for NEET-PG:** * **Erythema Nodosum (EN):** The *most common* skin manifestation of IBD. Unlike PG, EN activity **does** correlate with the severity of the intestinal flare. * **Pathergy:** PG exhibits pathergy, where minor trauma (like a needle prick or surgery) triggers new lesions. * **Sweet Syndrome:** Another neutrophilic dermatosis occasionally associated with IBD, presenting with "juicy" erythematous plaques and fever.

Q: Which of the following tests would be MOST useful for confirmation of Pemphigus vulgaris?

Tissue biopsy with direct immunofluorescence. **Explanation:** **Pemphigus vulgaris (PV)** is an autoimmune bullous disorder characterized by the formation of intraepidermal blisters. The pathogenesis involves IgG autoantibodies directed against **Desmoglein 3** (and sometimes Desmoglein 1), which are components of desmosomes. This leads to **acantholysis** (loss of keratinocyte adhesion). **Why Option D is Correct:** The gold standard for confirming a diagnosis of Pemphigus vulgaris is a **tissue biopsy** combined with **Direct Immunofluorescence (DIF)**. * **Histopathology:** Shows suprabasal splitting and "tombstoning" of the basal layer. * **DIF:** Performed on perilesional skin, it reveals a characteristic **"fish-net" or "chicken-wire" pattern** of IgG and C3 deposits along the intercellular substance of the epidermis. This confirms the presence and location of the autoantibodies. **Why Other Options are Incorrect:** * **A & C (Bacterial/Fungal Culture):** PV is an autoimmune disease, not an infectious one. While secondary infections can occur in denuded skin, cultures do not diagnose the primary pathology. * **B (Complete Blood Count):** CBC is non-specific. While it might show leukocytosis in cases of secondary infection, it cannot confirm an autoimmune blistering disorder. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive (extension of a blister or denudation of skin upon lateral pressure). * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei. * **Indirect Immunofluorescence (IIF):** Used to detect circulating antibodies; titers often correlate with disease activity. * **First-line Treatment:** Systemic corticosteroids (e.g., Prednisolone).

Q: Selective granular IgA deposit at dermal papillae tips is seen in which condition?

Dermatitis herpetiformis. ### Explanation **Correct Answer: B. Dermatitis herpetiformis** **Mechanism and Immunopathology:** Dermatitis herpetiformis (DH) is a cutaneous manifestation of gluten-sensitive enteropathy (Celiac disease). The hallmark of this condition is the presence of **granular IgA deposits** localized specifically at the **tips of the dermal papillae**. These deposits are formed by IgA antibodies directed against **epidermal transglutaminase (eTG)**, which cross-react with tissue transglutaminase (tTG) in the gut. This deposition triggers the recruitment of neutrophils, leading to the formation of microabscesses (Knot’s microabscesses) and subsequent subepidermal blistering. **Why other options are incorrect:** * **Bullous pemphigoid:** Characterized by **linear IgG and C3** deposits along the basement membrane zone (BMZ). It targets BP180 and BP230. * **Lichen planus:** Does not typically show specific diagnostic IgA/IgG patterns on Direct Immunofluorescence (DIF), though globular IgM deposits (Cytoid bodies) may be seen at the dermo-epidermal junction. * **Pemphigus vulgaris:** Characterized by **IgG and C3** deposits in a **"fish-net" or "lace-like"** pattern within the intercellular spaces of the epidermis (targeting Desmoglein 3 and 1). **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Intensely pruritic, symmetrical vesicles on extensor surfaces (elbows, knees, buttocks). * **Histopathology:** Subepidermal blister with **neutrophilic microabscesses** at dermal papillary tips. * **Association:** Strongly associated with **HLA-DQ2 and HLA-DQ8**. * **Treatment of Choice:** **Dapsone** (provides rapid symptomatic relief) and a strict **Gluten-free diet** (long-term management). * **Gold Standard Diagnosis:** Direct Immunofluorescence (DIF) of perilesional (uninvolved) skin showing granular IgA.

Q: Linear band of immunofluorescence (due to immunoglobulin deposition) along the dermoepidermal junction (Ribbon candy pattern) is seen in which of the following conditions?

Bullous pemphigoid. **Explanation:** The correct answer is **Bullous pemphigoid (BP)**. This condition is characterized by the production of autoantibodies (IgG) against the hemidesmosomal proteins **BP180 (BPAG2)** and **BP230 (BPAG1)** at the dermoepidermal junction (DEJ). On Direct Immunofluorescence (DIF), this results in a continuous, smooth, **linear band of IgG and C3** along the basement membrane zone, often described as a **"Ribbon candy"** or "tubular" pattern. **Analysis of Options:** * **Dermatitis herpetiformis:** Shows **granular** IgA deposits specifically at the tips of the dermal papillae, not a linear band. It is associated with Celiac disease. * **Pemphigus vulgaris:** Involves antibodies against Desmoglein 3 (and 1). DIF shows a **"fishnet" or "lace-like"** pattern of IgG/C3 within the epidermis (intercellular), not at the DEJ. * **Lichen planus:** Characterized by **shaggy** linear fibrinogen deposition at the DEJ and the presence of Civatte bodies (cytoid bodies) that stain with IgM. **High-Yield Clinical Pearls for NEET-PG:** * **Target Antigens:** BP180 (transmembrane) is the primary pathogenic target in Bullous Pemphigoid. * **Clinical Feature:** Tense bullae on an erythematous base (unlike the flaccid bullae of Pemphigus) that do not rupture easily. * **Histopathology:** Subepidermal blister with an inflammatory infiltrate rich in **eosinophils**. * **Nikolsky Sign:** Negative in Bullous Pemphigoid (Positive in Pemphigus).

Q: Pemphigus vulgaris is caused due to which type of hypersensitivity reaction?

Type II. **Explanation:** **Pemphigus vulgaris (PV)** is a classic example of a **Type II Hypersensitivity reaction**. In this condition, the body produces IgG autoantibodies (specifically against **Desmoglein 3** and **Desmoglein 1**) that target antigens located on the surface of keratinocytes. This is a "cytotoxic" or "antibody-mediated" reaction where the binding of antibodies leads to the loss of cell-to-cell adhesion (acantholysis), resulting in the formation of intraepidermal blisters. **Why other options are incorrect:** * **Type I (Immediate):** Mediated by IgE and mast cell degranulation (e.g., Anaphylaxis, Urticaria). PV involves IgG and a chronic autoimmune process. * **Type III (Immune-complex):** Caused by the deposition of antigen-antibody complexes in tissues (e.g., SLE, Post-streptococcal glomerulonephritis). In PV, the antibody binds directly to the fixed tissue antigen. * **Type IV (Delayed):** T-cell mediated reaction (e.g., Contact dermatitis, Tuberculin test). PV is primarily driven by humoral (antibody) immunity. **High-Yield Clinical Pearls for NEET-PG:** * **Target Antigen:** Desmoglein 3 (mucosal-dominant) and Desmoglein 1 (mucocutaneous). * **Immunofluorescence:** Direct Immunofluorescence (DIF) shows a characteristic **"Fish-net"** or "Lace-like" pattern of IgG/C3 deposition. * **Histopathology:** Shows **"Row of Tombstones"** appearance (basal layer remains attached to the basement membrane). * **Clinical Signs:** Positive **Nikolsky sign** and Bulla spread sign (Asboe-Hansen sign). * **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells/Tzanck corpuscles).

Question 1

Acantholysis, resulting from desmosome weakening by autoantibodies directed against the protein desmoglein, is the disease mechanism attributed to which of the following?

Accepted Answer

Pemphigus vulgaris

Answer

Epidermolysis bullosa

Answer

Mucous membrane pemphigoid

Answer

Herpes simplex infections

Question 2

A butterfly rash characteristically spares which of the following facial areas?

Accepted Answer

Nasolabial fold

Answer

Cheeks

Answer

Lower eyelids

Answer

Bridge of nose

Question 3

Which of the following is true regarding lichen planus?

Accepted Answer

Can undergo malignant change

Answer

Treated only by medication

Answer

Must be excised

Answer

Is an idiosyncrasy reaction

Question 4

"En coup de sabre" is seen in:

Accepted Answer

Scleroderma

Answer

Syphilis

Answer

Leprosy

Answer

Scabies

Question 5

Which of the following is a dermatological manifestation of Inflammatory Bowel Disease?

Accepted Answer

Pyoderma gangrenosum

Answer

Necrolytic migratory erythema

Answer

Impetigo

Answer

Psoriasis

Question 6

Which of the following tests would be MOST useful for confirmation of Pemphigus vulgaris?

Accepted Answer

Tissue biopsy with direct immunofluorescence

Answer

Bacterial culture

Answer

Complete blood count

Answer

Fungal culture

Question 7

Selective granular IgA deposit at dermal papillae tips is seen in which condition?

Accepted Answer

Dermatitis herpetiformis

Answer

Bullous pemphigoid

Answer

Lichen planus

Answer

Pemphigus vulgaris

Question 8

Linear band of immunofluorescence (due to immunoglobulin deposition) along the dermoepidermal junction (Ribbon candy pattern) is seen in which of the following conditions?

Accepted Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Answer

Pemphigus vulgaris

Answer

Lichen planus

Question 9

Pemphigus vulgaris is caused due to which type of hypersensitivity reaction?

Accepted Answer

Type II

Answer

Type I

Answer

Type III

Answer

Type IV

Question 10

A 85-year-old woman presents with blisters on her thigh and trunk that come on and off. Nikolsky sign is negative. What is the most likely cause?

Accepted Answer

Pemphigoid

Answer

Pemphigus vulgaris

Answer

Lichen planus

Answer

Dermatitis herpetiformis

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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