Autoimmune Skin Diseases Practice Questions

Q: 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?

Pemphigus vulgaris. **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.

Q: The Pathergy test is primarily used in the diagnosis of which condition?

Behçet's syndrome. **Explanation:** The **Pathergy test** is a diagnostic tool used to identify skin hyper-reactivity to minor trauma. It is a hallmark clinical feature of **Behçet's syndrome**, a multisystem inflammatory vasculitis. **Why Behçet's Syndrome is Correct:** The test involves pricking the skin (usually the forearm) with a sterile 20-gauge needle. A positive result is defined by the formation of a sterile **erythematous papule or pustule** (at least 2 mm in size) at the site of the prick within 24–48 hours. This occurs due to an exaggerated influx of neutrophils (neutrophilic dermatosis) in response to local trauma. While highly specific for Behçet's, its sensitivity varies geographically, being highest in patients from the "Silk Road" region (Middle East and East Asia). **Why Other Options are Incorrect:** * **Reiter’s Syndrome (Reactive Arthritis):** Characterized by the triad of urethritis, conjunctivitis, and arthritis. Cutaneous findings include *keratoderma blennorrhagicum* and *circinate balanitis*, but pathergy is not a feature. * **Lichen Planus:** Known for the **Koebner phenomenon** (isomorphic response), where new lesions of the same disease appear along lines of trauma. Unlike pathergy, these are not sterile pustules but typical lichenoid papules. * **Atopic Dermatitis:** A chronic pruritic inflammatory condition characterized by skin barrier dysfunction and IgE-mediated hypersensitivity, not neutrophilic hyper-reactivity. **NEET-PG High-Yield Pearls:** * **Differential Diagnosis for Pathergy:** Besides Behçet's, pathergy can also be seen in **Pyoderma Gangrenosum** and **Sweet Syndrome**. * **Behçet’s Triad:** Recurrent oral ulcers (most common), genital ulcers (most specific), and uveitis. * **HLA Association:** Strongly associated with **HLA-B51**. * **Treatment:** Colchicine is often the first-line agent for mucocutaneous symptoms.

Q: Desquamative gingivitis represents oral manifestations of all of the following except:

Erythema multiforme.. **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.

Q: Which of the following autoantibodies is most suggestive of subacute cutaneous lupus erythematosus?

anti Ro. **Explanation:** **Subacute Cutaneous Lupus Erythematosus (SCLE)** is a distinct subset of lupus erythematosus characterized by photosensitive, non-scarring annular or psoriasiform skin lesions. **Why Anti-Ro is correct:** The hallmark of SCLE is the presence of **Anti-Ro (SS-A) antibodies**, which are found in approximately **75–90%** of patients. These antibodies are highly specific for this clinical subtype and are also associated with neonatal lupus and Sjögren’s syndrome. Anti-Ro antibodies are thought to play a role in the photosensitivity characteristic of the disease. **Analysis of Incorrect Options:** * **Anti-dsDNA (Option A):** Highly specific for **Systemic Lupus Erythematosus (SLE)** and correlates with disease activity and lupus nephritis. It is rarely the primary marker for isolated cutaneous variants like SCLE. * **Anti-La (SS-B) (Option C):** Often found in conjunction with Anti-Ro (in about 30–40% of SCLE cases), but it is less frequently positive than Anti-Ro alone. Anti-Ro remains the "most suggestive" and primary marker. * **U1 RNP (Option D):** The diagnostic marker for **Mixed Connective Tissue Disease (MCTD)**. While it can be seen in SLE, it is not specifically associated with the SCLE phenotype. **High-Yield Clinical Pearls for NEET-PG:** * **Drug-Induced SCLE:** Often caused by Hydrochlorothiazide, Terbinafine, Calcium channel blockers, and ACE inhibitors. * **Neonatal Lupus:** Strongly associated with maternal Anti-Ro/La antibodies; the most serious complication is **congenital third-degree heart block**. * **Morphology:** SCLE lesions heal **without scarring** (unlike Discoid Lupus/DLE) but may leave behind temporary telangiectasia or hypopigmentation.

Q: Which of the following statements is FALSE regarding Sweet's syndrome?

Neutrophilia is not present. ***Neutrophilia is not present*** - **Neutrophilia** is actually a **hallmark feature** of Sweet's syndrome, making this statement false. - The condition is characterized by **dense neutrophilic infiltration** in the dermis and elevated **peripheral neutrophil count**. *May be associated with high fever* - **High fever** (>38°C) is a **major criterion** for diagnosing Sweet's syndrome. - Systemic symptoms including fever are present in approximately **80% of patients**. *May be associated with hematological malignancy* - **Acute myelogenous leukemia** is the most common associated malignancy in Sweet's syndrome. - Up to **20% of cases** are **malignancy-associated**, particularly with **hematological cancers**. *Pseudovesication* - **Pseudovesicles** are characteristic lesions that appear **vesicular** but lack true **intraepidermal fluid**. - This occurs due to **marked papillary dermal edema** causing separation at the **dermal-epidermal junction**.

Q: The Band test is indicated in which of the following conditions?

Systemic lupus erythematosus. The **Lupus Band Test (LBT)** is a direct immunofluorescence (DIF) technique used to detect the deposition of immunoglobulins (primarily IgG and IgM) and complement (C3) at the dermo-epidermal junction (DEJ). ### **Why Systemic Lupus Erythematosus (SLE) is Correct** In SLE, immune complexes deposit at the DEJ, appearing as a continuous or granular "band" under a fluorescence microscope. The test is highly specific for Lupus: * **Lesional LBT:** Performed on skin with a rash. It is positive in both Discoid LE (DLE) and SLE. * **Non-lesional LBT:** Performed on clinically normal skin. A positive result here is highly suggestive of **Systemic Lupus Erythematosus (SLE)** and helps differentiate it from localized cutaneous forms. ### **Why Other Options are Incorrect** * **A. Rheumatoid Arthritis:** While an autoimmune disease, it primarily affects synovium. It does not typically show specific immunoglobulin banding at the dermo-epidermal junction. * **C. Scleroderma:** Characterized by excessive collagen deposition and fibrosis. Diagnosis is clinical and supported by specific antibodies (Anti-Scl70, Anti-centromere), not the Band test. * **D. Polyarteritis Nodosa:** A systemic necrotizing vasculitis of medium and small-sized arteries. Diagnosis requires biopsy showing transmural inflammation of arteries, not DEJ immunofluorescence. ### **High-Yield Clinical Pearls for NEET-PG** * **Sun-exposed vs. Sun-protected skin:** A positive LBT in **sun-protected** normal skin (e.g., inner forearm) is a strong indicator of systemic involvement and high disease activity in SLE. * **False Positives:** Can occur in sun-damaged skin (actinic keratosis) or occasionally in Rosacea. * **Most common Ig:** **IgM** is the most frequently detected antibody in the Lupus Band Test.

Q: 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?

Hemidesmosome. ### 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).

Q: What is true about Erythema elevatum diutinum?

Dapsone is the drug of choice. **Erythema Elevatum Diutinum (EED)** is a rare, chronic form of localized cutaneous small-vessel vasculitis (leukocytoclastic vasculitis). ### **Explanation of Options** * **Dapsone is the drug of choice (Correct):** Dapsone is highly effective and considered the first-line treatment for EED. It works by inhibiting neutrophil chemotaxis and the deposition of antibodies, leading to rapid resolution of the lesions. * **Chronic cutaneous fungal infection (Incorrect):** EED is a **neutrophilic dermatosis** and a type of vasculitis, not an infection. It is often associated with underlying systemic conditions like IgA monoclonal gammopathy, HIV, or autoimmune diseases. * **Most common site is the trunk (Incorrect):** The hallmark of EED is its **symmetrical distribution over extensor surfaces** of the joints (knees, elbows, small joints of hands and feet). The trunk is rarely involved. * **Cutaneous marker of glucagonoma (Incorrect):** The cutaneous marker for a glucagonoma is **Necrolytic Migratory Erythema (NME)**. EED is instead a marker for plasma cell dyscrasias (specifically IgA paraproteinemia). ### **Clinical Pearls for NEET-PG** * **Morphology:** Presents as red-violet to yellowish-brown papules, plaques, or nodules that eventually become fibrotic. * **Histopathology:** Early lesions show **Leukocytoclastic Vasculitis (LCV)** with a "starry sky" appearance of nuclear dust. Older lesions show characteristic **concentric perivascular fibrosis** (onion-skinning). * **Key Association:** Always screen patients with EED for **IgA Monoclonal Gammopathy**, as this is the most common systemic association. * **Differential Diagnosis:** Sweet Syndrome (also a neutrophilic dermatosis but presents with fever and painful plaques) and Granuloma Faciale.

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

Pemphigus. **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.

Q: Acantholytic cells are typically found in the blister cavity in which of the following conditions?

Pemphigus. ### Explanation **Correct Answer: A. Pemphigus** **1. Why Pemphigus is correct:** The hallmark of Pemphigus (specifically Pemphigus Vulgaris) is **acantholysis**, which refers to the loss of intercellular connections (desmosomes) between keratinocytes. This is caused by IgG autoantibodies against **Desmoglein 1 and 3**. When these connections break, the keratinocytes become rounded, detached, and float within the blister cavity. These detached cells are known as **Tzanck cells** or acantholytic cells. Because the split occurs within the epidermis (intraepidermal), these cells are easily visible in a Tzanck smear. **2. Why the other options are incorrect:** * **Bullous Pemphigoid:** This is a **subepidermal** blistering disease where autoantibodies (anti-BP180/230) target the hemidesmosomes at the dermo-epidermal junction. Since the entire epidermis lifts off the dermis intact, there is no intraepidermal cell detachment (no acantholysis). * **Epidermolysis Bullosa:** This represents a group of genetic mechanobullous disorders caused by structural protein defects (like Keratin 5/14 or Collagen VII). The split occurs due to structural fragility, not immunologic acantholysis. * **Dermatitis Herpetiformis:** This is characterized by subepidermal neutrophils forming **microabscesses at the dermal papillary tips**. It is associated with Celiac disease and IgA deposits, but does not involve acantholysis. **3. NEET-PG High-Yield Pearls:** * **Tzanck Smear:** Used for rapid diagnosis. Look for "Acantholytic cells" in Pemphigus and "Multinucleated giant cells" in Herpes Simplex/Varicella. * **Nikolsky Sign:** Positive in Pemphigus (due to acantholysis) but negative in Bullous Pemphigoid. * **Row of Tombstones:** Histopathological appearance of the basal layer in Pemphigus Vulgaris. * **Immunofluorescence:** Pemphigus shows a **"Fish-net"** or reticular pattern, while Bullous Pemphigoid shows a **linear** pattern along the basement membrane.

Question 1

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?

Accepted Answer

Pemphigus vulgaris

Answer

Bullous pemphigoid

Answer

Paraneoplastic pemphigus

Answer

Dermatitis herpetiformis

Question 2

The Pathergy test is primarily used in the diagnosis of which condition?

Accepted Answer

Behçet's syndrome

Answer

Reiter's syndrome

Answer

Lichen planus

Answer

Atopic dermatitis

Question 3

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

Accepted Answer

Erythema multiforme.

Answer

Erosive lichen planus.

Answer

Benign mucous membrane pemphigoid.

Answer

Pemphigus.

Question 4

Which of the following autoantibodies is most suggestive of subacute cutaneous lupus erythematosus?

Accepted Answer

anti Ro

Answer

anti ds DNA

Answer

anti La

Answer

U1 RNP

Question 5

Which of the following statements is FALSE regarding Sweet's syndrome?

Accepted Answer

Neutrophilia is not present

Answer

May be associated with high fever

Answer

May be associated with hematological malignancy

Answer

Pseudovesication

Question 6

The Band test is indicated in which of the following conditions?

Accepted Answer

Systemic lupus erythematosus

Answer

Rheumatoid arthritis

Answer

Scleroderma

Answer

Polyarteritis nodosa

Question 7

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?

Accepted Answer

Hemidesmosome

Answer

Keratinocyte cell membrane

Answer

Lamina densa

Answer

Nucleus

Question 8

What is true about Erythema elevatum diutinum?

Accepted Answer

Dapsone is the drug of choice

Answer

Chronic cutaneous fungal infection

Answer

Most common site of involvement is the trunk

Answer

A cutaneous marker of glucagonoma

Question 9

Trismus is not seen in which of the following conditions?

Accepted Answer

Pemphigus

Answer

Scleroderma

Answer

Oral submucous fibrosis (OSMF)

Answer

None of the above

Question 10

Acantholytic cells are typically found in the blister cavity in which of the following conditions?

Accepted Answer

Pemphigus

Answer

Bullous pemphigoid

Answer

Epidermolysis bullosa

Answer

Dermatitis herpetiformis

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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