Autoimmune Skin Diseases Practice Questions

Q: 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?

Oral mucosal lesions. **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).

Q: The fishnet pattern is seen in which of the following conditions?

Pemphigus vulgaris. In **Pemphigus Vulgaris (PV)**, the "fishnet" or "chicken-wire" pattern is a classic finding on **Direct Immunofluorescence (DIF)**. This occurs because IgG antibodies (and sometimes C3) are deposited against **Desmoglein 3** (and 1), which are components of desmosomes. Since desmosomes connect keratinocytes throughout the epidermis, the antibodies outline the entire cell surface, creating a characteristic reticular or lace-like appearance. ### Explanation of Options: * **Pemphigus Vulgaris (Correct):** Characterized by intraepidermal acantholysis. The DIF shows intercellular IgG/C3 deposition in a **fishnet pattern**. * **Bullous Pemphigoid:** This is a subepidermal blistering disease where antibodies target BP180/BP230 at the dermo-epidermal junction. DIF shows a **linear band** of IgG and C3 along the basement membrane zone (BMZ). * **Dermatitis Herpetiformis:** Associated with Celiac disease, DIF reveals **granular IgA deposits** specifically at the tips of the dermal papillae. * **Darier’s Disease:** This is an autosomal dominant genodermatosis caused by a mutation in the ATP2A2 gene. While it involves acantholysis, it is not antibody-mediated; therefore, DIF is typically negative. ### High-Yield Clinical Pearls for NEET-PG: * **Tzanck Smear in PV:** Shows "Tzanck cells" (rounded, acantholytic keratinocytes with hyperchromatic nuclei). * **Histopathology of PV:** "Row of tombstones" appearance (basal layer remains attached to the BMZ). * **Nikolsky Sign:** Positive in Pemphigus Vulgaris; Negative in Bullous Pemphigoid. * **Indirect Immunofluorescence (IIF):** In PV, IIF uses monkey esophagus as a substrate to detect circulating antibodies.

Q: Bullae of bullous pemphigoid are:

Subepidermal. **Explanation:** **Bullous Pemphigoid (BP)** is an autoimmune blistering disease characterized by the formation of **subepidermal bullae**. The underlying pathophysiology involves the production of IgG autoantibodies against hemidesmosomal proteins, specifically **BP180 (BPAG2)** and **BP230 (BPAG1)**. These proteins are responsible for anchoring the basal layer of the epidermis to the basement membrane. When these proteins are targeted, the entire epidermis detaches from the dermis, creating a deep-seated, tense blister. **Analysis of Options:** * **Subepidermal (Correct):** Because the split occurs at the level of the basement membrane zone (below the epidermis), the roof of the blister consists of the full thickness of the epidermis. This makes the bullae **tense** and less likely to rupture easily. * **Intraepidermal (Incorrect):** This is characteristic of the **Pemphigus group** (e.g., Pemphigus Vulgaris). In these conditions, antibodies target desmogleins (cell-to-cell adhesion), leading to acantholysis and flaccid blisters that rupture easily. * **Subdermal (Incorrect):** This term refers to the layer below the dermis (subcutaneous fat). Blistering diseases are classified based on their relationship to the epidermis and dermis, not the subcutaneous tissue. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Feature:** Tense bullae on an erythematous base, often preceded by a pre-eruptive "urticarial" phase. * **Nikolsky Sign:** Negative (unlike Pemphigus). * **Direct Immunofluorescence (DIF):** Shows **linear** deposition of IgG and C3 along the basement membrane zone. * **Salt-split skin study:** Fluorescence is seen on the **roof** (epidermal side) of the split. * **Epidemiology:** Typically affects the elderly (>60 years).

Q: Gottron papules are pathognomonic for which condition?

Dermatomyositis. **Explanation:** **1. Why Dermatomyositis is Correct:** Gottron papules are considered **pathognomonic** (specifically diagnostic) for Dermatomyositis. They are characterized by symmetric, violaceous (purplish), flat-topped papules or plaques found over the dorsal aspects of the interphalangeal and metacarpophalangeal joints. The underlying mechanism involves interface dermatitis, leading to inflammation at the dermo-epidermal junction. **2. Why Other Options are Incorrect:** * **Inclusion body myositis (IBM):** While it is an inflammatory myopathy, it typically lacks the classic cutaneous hallmarks of dermatomyositis. It presents with insidious, asymmetric muscle weakness, particularly affecting the finger flexors and quadriceps. * **Polymyositis:** This is a systemic inflammatory myopathy that shares similar muscle involvement with dermatomyositis but **lacks the characteristic skin rashes** (Gottron papules, Heliotrope rash). * **Discoid lupus erythematosus (DLE):** DLE presents with well-demarcated, erythematous, scaly plaques that lead to scarring and atrophy. Crucially, DLE lesions on the hands typically occur in the **inter-articular** areas (between the joints), whereas Gottron papules occur directly **over** the joints. **3. NEET-PG High-Yield Clinical Pearls:** * **Heliotrope Rash:** Violaceous edema of the upper eyelids; another hallmark of Dermatomyositis. * **Gottron Sign:** Macular erythema (not papules) over the knuckles, elbows, or knees. * **Shawl Sign/V-Sign:** Photosensitive erythema over the back/shoulders or upper chest. * **Mechanic’s Hands:** Hyperkeratosis and fissuring of the palms and lateral fingers (associated with **Anti-Jo-1** antibodies/Antisynthetase syndrome). * **Malignancy Link:** Dermatomyositis in adults is frequently a **paraneoplastic syndrome**; always screen for underlying internal malignancies (e.g., ovarian, lung, GI).

Q: Gottron sign is seen in which of the following conditions?

Dermatomyositis. **Explanation:** **Gottron sign** is a pathognomonic cutaneous manifestation of **Dermatomyositis (DM)**. It is characterized by symmetric, erythematous to violaceous scales or macules overlying the dorsal aspect of the interphalangeal (IP) and metacarpophalangeal (MCP) joints [1]. This occurs due to underlying microvascular damage and inflammation specific to the pathophysiology of DM. **Why the other options are incorrect:** * **Polymyositis (PM):** While PM shares similar proximal muscle weakness with DM [2], it is strictly an inflammatory myopathy **without** the characteristic skin involvement. If a patient has the clinical features of PM plus Gottron sign, the diagnosis automatically shifts to Dermatomyositis [2]. * **Sjogren’s Syndrome:** This is primarily characterized by sicca symptoms (dry eyes/mouth). While it can overlap with other connective tissue diseases, Gottron sign is not a feature. * **Systemic Lupus Erythematosus (SLE):** SLE presents with a malar rash that typically **spares the nasolabial folds**. On the hands, SLE rashes usually occur **between the joints** (interarticular), whereas Gottron sign specifically occurs **over the joints**. **High-Yield Clinical Pearls for NEET-PG:** * **Gottron Papules:** Raised, lichenoid papules over the knuckles (more specific than the "sign") [1]. * **Heliotrope Rash:** Violaceous eruption on the upper eyelids with periorbital edema [1]. * **Shawl Sign/V-sign:** Erythema over the upper back/shoulders or anterior chest [1]. * **Mechanic’s Hands:** Hyperkeratotic, cracked skin on the lateral fingers (associated with **Anti-Jo-1** antibodies and Interstitial Lung Disease) [2]. * **Malignancy:** Dermatomyositis has a strong association with internal malignancies (e.g., ovarian, lung, gastric); age-appropriate cancer screening is mandatory upon diagnosis [1].

Q: A 40-year-old woman presented with an 8-month history of erythema and swelling of the periorbital region, papules and plaques on the dorsolateral aspect of forearms and knuckles, and ragged cuticles. There was no muscle weakness. What is the most likely diagnosis?

Dermatomyositis. **Explanation:** The clinical presentation is classic for **Dermatomyositis (DM)**. The diagnosis is based on the presence of pathognomonic cutaneous markers: 1. **Heliotrope Rash:** Erythema and edema of the periorbital region. 2. **Gottron’s Papules:** Violaceous papules and plaques over the knuckles (MCP, PIP, DIP joints) and dorsolateral forearms. 3. **Samitz’s Sign:** Ragged cuticles and periungual telangiectasia. Notably, the absence of muscle weakness suggests **Amyopathic Dermatomyositis**, a variant where characteristic skin lesions occur without clinical or laboratory evidence of myositis for at least 6 months. **Why other options are incorrect:** * **SLE:** While it causes malar rashes, it typically **spares the nasolabial folds** and involves the interjoint areas of the fingers rather than the knuckles (Gottron’s). * **Systemic Sclerosis:** Characterized by skin tightening (sclerodactyly), Raynaud’s phenomenon, and "beaked nose" facies, rather than inflammatory periorbital edema or Gottron’s papules. * **Mixed Connective Tissue Disorder (MCTD):** Usually presents with overlapping features of SLE, Scleroderma, and Polymyositis, often with high titers of **Anti-U1 RNP** antibodies. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic signs:** Gottron’s papules and Heliotrope rash. * **Shawl sign:** Erythema over the upper back and shoulders. * **V-sign:** Erythema over the anterior neck and upper chest. * **Mechanic’s hands:** Hyperkeratotic, fissured skin on the lateral aspects of fingers (associated with **Anti-Jo-1** antibodies and interstitial lung disease). * **Malignancy:** Dermatomyositis in adults is associated with an increased risk of internal malignancies (Ovarian, Lung, Gastric).

Q: In cicatricial pemphigoid, which antigen is bound by IgG on the epidermal side when using the salt split skin technique?

XVII collagen. **Explanation:** **Cicatricial Pemphigoid (Mucous Membrane Pemphigoid)** is a chronic autoimmune subepidermal blistering disease that primarily affects mucous membranes and leads to scarring (cicatrix). 1. **Why Option A is Correct:** The **Salt Split Skin (SSS)** technique involves incubating skin in 1M NaCl to separate the epidermis from the dermis through the *lamina lucida*. In Cicatricial Pemphigoid, the autoantibodies (IgG) can target different antigens. When the target is **Type XVII Collagen (BP180)**, the antigen remains attached to the hemidesmosomes on the **epidermal roof** (base of the basal keratinocytes). Therefore, immunofluorescence shows staining on the epidermal side of the split. 2. **Why Other Options are Incorrect:** * **B & C (Epiligrin/Laminin 5):** These are the same entity. Anti-epiligrin cicatricial pemphigoid is a specific subtype associated with an increased risk of solid organ malignancy. On SSS, these antigens are located in the lower part of the lamina lucida and thus stain the **dermal floor**. * **D (BP Antigen 1 & 2):** While BP180 (BPAG2) is involved, BP230 (BPAG1) is purely intracellular. In classic Bullous Pemphigoid, staining is typically on the epidermal side, but the question specifically asks for the antigen associated with the epidermal side in the context of *Cicatricial Pemphigoid*. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Oral mucosa (Desquamative gingivitis). * **Most serious complication:** Ocular involvement leading to symblepharon, ankyloblepharon, and blindness. * **Salt Split Skin Rule:** * **Epidermal side (Roof):** Bullous Pemphigoid, Cicatricial Pemphigoid (BP180 type). * **Dermal side (Floor):** Epidermolysis Bullosa Acquisita (EBA), Anti-Laminin 332 (Epiligrin) Pemphigoid. * **Mnemonic:** "E" for Epidermal = BP; "D" for Dermal = EBA.

Q: Which of the following statements regarding lichen planus is false?

Corticosteroids are not used in its treatment.. **Explanation:** Lichen Planus (LP) is a chronic, inflammatory, T-cell mediated autoimmune condition. The statement **"Corticosteroids are not used in its treatment" is false** because corticosteroids are, in fact, the **first-line treatment** for LP. Topical steroids (e.g., Clobetasol) are used for localized lesions, while systemic steroids are indicated for severe, generalized, or rapidly progressing cases to suppress the immune-mediated destruction of keratinocytes. **Analysis of other options:** * **Option A (Pruritic lesions):** This is a hallmark feature. LP is classically described by the **6 P's**: Planar (flat-topped), Purple, Polygonal, Pruritic, Papules, and Plaques. The itching is often intense. * **Option B (Nail involvement):** Occurs in about 10% of cases. Characteristic findings include longitudinal ridging, splitting, and the pathognomonic **Pterygium formation** (V-shaped extension of the proximal nail fold onto the nail bed). * **Option C (Mucous membranes):** Frequently involved (Oral LP). It often presents as **Wickham striae** (a white, reticulate, lace-like pattern), most commonly on the buccal mucosa. **NEET-PG High-Yield Pearls:** * **Histopathology:** Shows "saw-tooth" appearance of rete ridges, Civatte bodies (apoptotic keratinocytes), and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo). * **Associations:** Strongly associated with **Hepatitis C virus** infection. * **Grinspan’s Syndrome:** Triad of Oral Lichen Planus, Hypertension, and Diabetes Mellitus.

Q: A 45-year-old female presents with a history of blisters on her body, which subsequently rupture, leading to severe skin pain. The condition begins in the mouth and involves peeling of the skin upon applying pressure. The dermatologist identified a loss of cellular cohesion, specifically involving desmosomes 3 and 1. What is the most likely diagnosis?

Pemphigus vulgaris. **Explanation:** The clinical presentation and pathophysiology point directly to **Pemphigus Vulgaris (PV)**. **Why Pemphigus Vulgaris is Correct:** 1. **Mucosal Involvement:** PV typically begins in the oral cavity (mouth) before progressing to the skin. 2. **Nikolsky Sign:** The "peeling of skin upon applying pressure" is a positive Nikolsky sign, characteristic of intraepidermal blistering where cell-to-cell adhesion is lost. 3. **Pathophysiology:** The question specifies the loss of cellular cohesion (acantholysis) due to antibodies against **Desmoglein 3 (mucosal-dominant)** and **Desmoglein 1 (mucocutaneous)**. These are components of desmosomes. **Why Other Options are Incorrect:** * **Pemphigus Foliaceus:** This involves antibodies against **Desmoglein 1 only**. It is more superficial, lacks mucosal involvement, and presents with "cornflake" crusts rather than deep erosions. * **Bullous Pemphigoid:** This is a subepidermal blistering disease involving hemidesmosomes (BP180/230). Blisters are **tense**, Nikolsky sign is negative, and mucosal involvement is rare. * **Dermatitis Herpetiformis:** Associated with Celiac disease, it presents as intensely pruritic vesicles on extensor surfaces. Histology shows IgA deposits in dermal papillae, not desmosomal destruction. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Look for the **"Row of Tombstones"** appearance (basal layer remains attached to the basement membrane). * **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells)—large, round keratinocytes with hyperchromatic nuclei. * **Immunofluorescence:** Direct Immunofluorescence (DIF) shows a **"Fishnet" or "Lace-like"** pattern of IgG/C3 deposits. * **Treatment:** Systemic corticosteroids are the mainstay; Rituximab is now considered first-line therapy.

Question 1

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?

Accepted Answer

Oral mucosal lesions

Answer

Eosinophils within bullae

Answer

IgA deposits on basement membrane

Answer

Negative Nikolsky sign

Question 2

A 63-year-old woman presents with skin lesions and difficulty rising from a chair. A clinical diagnosis of dermatomyositis is made. What skin and clinical findings might be associated with this condition?

Accepted Answer

Discoloration of the upper eyelids (heliotrope rash)

Answer

Lesions rarely involve the border of the scalp

Answer

Skin manifestations are permanent

Answer

Skin findings are aggravated by sunlight exposure

Question 3

The fishnet pattern is seen in which of the following conditions?

Accepted Answer

Pemphigus vulgaris

Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Answer

Darier's disease

Question 4

Bullae of bullous pemphigoid are:

Accepted Answer

Subepidermal

Answer

Intraepidermal

Answer

Subdermal

Answer

None

Question 5

Gottron papules are pathognomonic for which condition?

Accepted Answer

Dermatomyositis

Answer

Inclusion body myositis

Answer

Polymyositis

Answer

Discoid lupus erythematosus

Question 6

Gottron sign is seen in which of the following conditions?

Accepted Answer

Dermatomyositis

Answer

Polymyositis

Answer

Polymyositis and Sjogren's syndrome

Answer

Polymyositis and SLE

Question 7

A 40-year-old woman presented with an 8-month history of erythema and swelling of the periorbital region, papules and plaques on the dorsolateral aspect of forearms and knuckles, and ragged cuticles. There was no muscle weakness. What is the most likely diagnosis?

Accepted Answer

Dermatomyositis

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Systemic sclerosis

Answer

Mixed connective tissue disorder

Question 8

In cicatricial pemphigoid, which antigen is bound by IgG on the epidermal side when using the salt split skin technique?

Accepted Answer

XVII collagen

Answer

Epiligrin

Answer

Laminin 5

Answer

BP antigen 1 & 2

Question 9

Which of the following statements regarding lichen planus is false?

Accepted Answer

Corticosteroids are not used in its treatment.

Answer

It presents with pruritic lesions.

Answer

It can involve the nails.

Answer

It can involve mucous membranes.

Question 10

A 45-year-old female presents with a history of blisters on her body, which subsequently rupture, leading to severe skin pain. The condition begins in the mouth and involves peeling of the skin upon applying pressure. The dermatologist identified a loss of cellular cohesion, specifically involving desmosomes 3 and 1. What is the most likely diagnosis?

Accepted Answer

Pemphigus vulgaris

Answer

Pemphigus foliaceus

Answer

Bullous pemphigoid

Answer

Dermatitis herpetiformis

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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