Autoimmune Skin Diseases Practice Questions

Q: Chloroquine is used in the treatment of which of the following dermatological conditions?

Discoid Lupus Erythematosus (DLE). **Explanation:** **Chloroquine** and its derivative, Hydroxychloroquine (HCQ), are **antimalarial agents** that have become a cornerstone in the management of various connective tissue disorders. **1. Why DLE is the Correct Answer:** Discoid Lupus Erythematosus (DLE) is a chronic, scarring form of cutaneous lupus. Antimalarials are the **first-line systemic treatment** for DLE. They work by inhibiting antigen presentation, reducing the production of pro-inflammatory cytokines (like IFN-alpha), and protecting the skin from UV-induced damage by stabilizing lysosomal membranes. They are particularly effective for patients who do not respond adequately to topical corticosteroids or calcineurin inhibitors. **2. Why Other Options are Incorrect:** * **Pemphigus:** This is an autoimmune blistering disease treated primarily with systemic corticosteroids and immunosuppressants (e.g., Azathioprine, Rituximab). * **Psoriasis:** Chloroquine is generally **contraindicated** in psoriasis as it can trigger a flare-up or cause the disease to transition into a more severe form, such as erythrodermic or pustular psoriasis. * **Nummular Eczema:** This is an inflammatory skin condition treated with emollients, topical steroids, and phototherapy; antimalarials have no role in its management. **3. NEET-PG High-Yield Pearls:** * **Ocular Toxicity:** The most significant side effect of long-term Chloroquine use is **retinopathy** (Bull’s eye maculopathy). Baseline and periodic ophthalmological exams are mandatory. * **Other Indications:** Antimalarials are also used in Systemic Lupus Erythematosus (SLE), Porphyria Cutanea Tarda (PCT), and Polymorphous Light Eruption (PMLE). * **Smoking Interference:** Smoking significantly reduces the clinical efficacy of antimalarials in patients with cutaneous lupus.

Q: Acantholysis is characteristic of which of the following conditions?

Pemphigus vulgaris. **Explanation:** **Acantholysis** is the hallmark pathological process of the **Pemphigus** group of diseases. It refers to the loss of intercellular connections (desmosomes) between keratinocytes, leading to the formation of intraepidermal clefts and blisters. In **Pemphigus vulgaris**, IgG autoantibodies target **Desmoglein 3** (and sometimes Desmoglein 1), resulting in "row of tombstone" appearance on histology due to the loss of cohesion between suprabasal cells. **Why other options are incorrect:** * **Pemphigoid (Bullous Pemphigoid):** This is a **subepidermal** blistering disease. The pathology involves autoantibodies against BP180 and BP230 in the hemidesmosomes. There is no acantholysis; instead, the entire epidermis detaches from the dermis. * **Erythema Multiforme:** This is a hypersensitivity reaction characterized by "target lesions." Histologically, it shows vacuolar degeneration of the basal layer and individual keratinocyte necrosis, not acantholysis. * **Dermatitis Herpetiformis:** This is an IgA-mediated autoimmune disease associated with Celiac disease. It is characterized by **subepidermal** blisters and neutrophilic microabscesses at the dermal papillary tips. **High-Yield Clinical Pearls for NEET-PG:** * **Nikolsky Sign:** Positive in Pemphigus (due to acantholysis) but negative in Pemphigoid. * **Tzanck Smear:** Shows **Acantholytic cells (Tzanck cells)**—large, round keratinocytes with hyperchromatic nuclei and a peripheral halo of cytoplasm. * **Immunofluorescence:** Pemphigus shows a **"fishnet" or "lace-like"** pattern of IgG deposition, whereas Bullous Pemphigoid shows **linear** IgG/C3 deposition along the basement membrane zone.

Q: In pemphigus, circulating antibodies attack which components?

Desmoglein 1 and 3. **Explanation:** Pemphigus is a group of life-threatening autoimmune blistering diseases characterized by **acantholysis** (loss of cell-to-cell adhesion). The underlying pathophysiology involves the production of IgG autoantibodies against **Desmogleins (Dsg)**, which are calcium-dependent transmembrane glycoproteins belonging to the cadherin family. These proteins are vital components of **desmosomes**, the "glue" that holds keratinocytes together. * **Pemphigus Vulgaris (PV):** The most common form. Antibodies primarily target **Dsg 3** (found in mucosal surfaces) and **Dsg 1** (found in the skin). This leads to mucosal ulcers and flaccid skin bullae. * **Pemphigus Foliaceus (PF):** Antibodies target **Dsg 1** only, resulting in superficial blisters and crusting without mucosal involvement. **Analysis of Options:** * **Option B (Correct):** Dsg 1 and Dsg 3 are the primary targets in the Pemphigus group. * **Options A, C, and D (Incorrect):** While Desmoglein 2 and 4 exist, they are not the primary antigenic targets in classic Pemphigus. Dsg 2 is expressed in simple epithelia and the heart, while Dsg 4 is primarily expressed in hair follicles. **High-Yield Clinical Pearls for NEET-PG:** 1. **Nikolsky Sign:** Positive (gentle pressure on normal-looking skin causes perilesional skin to peel). 2. **Tzanck Smear:** Shows **Acantholytic cells** (Tzanck cells/Rowley cells)—large, round keratinocytes with hyperchromatic nuclei. 3. **Histopathology:** Characterized by **suprabasal splitting** and a "row of tombstones" appearance (basal layer remains attached to the basement membrane). 4. **Direct Immunofluorescence (DIF):** Shows a characteristic **"fishnet" or "lace-like"** pattern of IgG and C3 deposits in the intercellular spaces.

Q: Which of the following antigens are associated with cicatricial pemphigoid?

BPAG2 and epiligrin. **Explanation:** **Cicatricial Pemphigoid (Mucous Membrane Pemphigoid)** is a chronic, autoimmune subepidermal blistering disease primarily affecting the mucous membranes (oral, ocular, and genital) and frequently leading to scarring (cicatrization). 1. **Why Option A is Correct:** The pathogenesis involves autoantibodies directed against components of the dermo-epidermal junction. The most common target antigens are **BPAG2 (BP180)**, specifically the C-terminus, and **Laminin 332 (Epiligrin)**. * **BPAG2** is associated with the mucosal-predominant form. * **Epiligrin (Laminin 332)** is a high-yield association because patients with anti-epiligrin cicatricial pemphigoid have a significantly **increased risk of solid organ malignancies** (adenocarcinomas). 2. **Why Other Options are Incorrect:** * **Options B, C, and D:** These refer to Human Leukocyte Antigen (HLA) types. While certain HLAs (like HLA-DQB1*0301) are associated with Cicatricial Pemphigoid, the question specifically asks for **antigens** (the proteins targeted by antibodies), not genetic susceptibility markers. HLA DR5, B8, and DR3 are more commonly linked to other autoimmune conditions like Dermatitis Herpetiformis or Systemic Lupus Erythematosus. **High-Yield Clinical Pearls for NEET-PG:** * **Site:** Most common site is the **oral mucosa** (desquamative gingivitis), but the most serious complication is **ocular involvement** (symblepharon, ankyloblepharon, and blindness). * **Direct Immunofluorescence (DIF):** Shows linear IgG and C3 deposits at the basement membrane zone. * **Salt-split skin test:** Fluorescence occurs on the **roof** (epidermal side) if targeting BP180, or the **floor** (dermal side) if targeting Laminin 332. * **Key Association:** Always screen for internal malignancy if anti-epiligrin antibodies are present.

Q: Desmoplakin is the target antigen in which of the following conditions?

Paraneoplastic pemphigus.. ### Explanation **Correct Answer: B. Paraneoplastic pemphigus** **Medical Concept:** Paraneoplastic Pemphigus (PNP) is a severe autoimmune blistering disease associated with underlying malignancies (most commonly Non-Hodgkin Lymphoma and CLL). Unlike other forms of pemphigus, PNP is characterized by a **polymorphic** autoantibody profile. The autoantibodies target not only the desmogleins (Dsg 1 and 3) but also members of the **Plakin family**, specifically **Desmoplakin I and II**, Bullous Pemphigoid Antigen 1 (BP230), Periplakin, and Envoplakin. These proteins are intracellular components of the desmosome and hemidesmosome, and their destruction leads to extensive acantholysis. **Analysis of Incorrect Options:** * **A. Pemphigus vulgaris:** The primary target antigens are **Desmoglein 3** (mucosal-dominant) and **Desmoglein 1** (mucocutaneous). It does not typically involve plakin proteins. * **C. Drug-induced pemphigus:** This most commonly mimics Pemphigus foliaceus or vulgaris. The antigens are usually **Desmoglein 1 or 3**. Common culprits include Thiol group drugs like D-penicillamine and Captopril. * **D. Pemphigus foliaceous:** The target antigen is strictly **Desmoglein 1**, leading to very superficial (subcorneal) blisters. **High-Yield Clinical Pearls for NEET-PG:** * **Most common association:** Non-Hodgkin Lymphoma (NHL) is the most frequent malignancy associated with PNP. In children, it is often associated with Castleman disease. * **Clinical Hallmark:** Severe, intractable **stomatitis** (painful oral ulcerations) that involves the tongue and extends to the oropharynx. * **Unique Feature:** PNP can involve the respiratory epithelium, leading to **Bronchiolitis Obliterans**, which is a major cause of mortality. * **Immunofluorescence:** Direct Immunofluorescence (DIF) shows IgG and C3 in the intercellular spaces (fishnet pattern) AND along the basement membrane zone (linear pattern).

Q: Pyoderma gangrenosum is most commonly associated with which of the following conditions?

Ulcerative colitis. **Explanation:** **Pyoderma gangrenosum (PG)** is a rare, non-infectious neutrophilic dermatosis characterized by painful, rapidly enlarging ulcers with undermined, violaceous edges. It is a classic **extraintestinal manifestation (EIM)** of Inflammatory Bowel Disease (IBD). **1. Why Ulcerative Colitis (UC) is the correct answer:** While PG is associated with both types of IBD, it is statistically **more common in Ulcerative Colitis** than in Crohn’s disease. Approximately 1–5% of UC patients develop PG. Crucially, the clinical course of PG does not always parallel the bowel disease activity; it can occur even when the colitis is in remission or after a total proctocolectomy. **2. Why the other options are incorrect:** * **Crohn’s disease:** Although PG occurs in Crohn’s, it is less frequent than in UC. Crohn’s is more specifically associated with *Erythema Nodosum*, which, unlike PG, usually correlates closely with the severity of bowel inflammation. * **Amoebic colitis:** This is an infectious etiology caused by *Entamoeba histolytica*. It presents with "flask-shaped" ulcers in the colon but does not have an autoimmune association with PG. * **Ischemic colitis:** This results from decreased blood flow to the colon (usually at Griffith’s point). It is a vascular/mechanical issue and does not trigger the systemic neutrophilic response seen in PG. **Clinical Pearls for NEET-PG:** * **Most common EIM of IBD:** Peripheral arthritis (Type 1 is pauciarticular; Type 2 is polyarticular). * **Skin manifestations:** Erythema Nodosum (more common in Crohn's) vs. Pyoderma Gangrenosum (more common in UC). * **Treatment of PG:** The mainstay is systemic corticosteroids or immunosuppressants (e.g., Cyclosporine, Infliximab). **Do not debride** these ulcers, as it can lead to worsening of the lesion due to **pathergy** (trauma-induced skin injury).

Q: What is the percentage of patients with disseminated discoid lupus erythematosus who develop systemic lupus erythematosus?

22%. **Explanation:** The progression of Discoid Lupus Erythematosus (DLE) to Systemic Lupus Erythematosus (SLE) depends significantly on the distribution of skin lesions. DLE is categorized into two types: **Localized** (lesions confined to the head and neck) and **Disseminated** (lesions occurring both above and below the neck). 1. **Why 22% is correct:** While only about **5%** of patients with localized DLE progress to SLE, the risk increases significantly in the disseminated form. Clinical studies and standard dermatology textbooks (such as Fitzpatrick) indicate that approximately **22%** of patients with disseminated DLE will eventually develop systemic involvement. The presence of lesions on the trunk and extremities often correlates with a higher frequency of immunological abnormalities (like ANA positivity). 2. **Why other options are incorrect:** * **A (2%):** This is too low; even localized DLE has a higher conversion rate (~5%). * **C (52%) & D (82%):** These figures are overestimates. While disseminated DLE carries a higher risk than localized DLE, the majority of patients (nearly 80%) still do not develop full-blown systemic disease. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site for DLE:** The concha of the ear. * **Classic Histology:** Interface dermatitis, follicular plugging, and basement membrane thickening. * **Lupus Band Test (LBT):** In DLE, the LBT is positive in **lesional skin** only. In SLE, the LBT can be positive in both lesional and **sun-exposed non-lesional skin**. * **Risk Factor:** Patients with disseminated DLE and high-titer ANA are at the highest risk for progression to SLE.

Q: A 45-year-old patient presents with itchy, flat-topped, polygonal, violaceous papules on the inner wrists and flexors surfaces of the forearms. The lesions have a characteristic shiny surface and are arranged in a linear pattern. The patient denies any recent medication changes. What is the treatment?

Topical steroids. ***Topical steroids***- **Lichen planus** is an inflammatory, immune-mediated disorder, and high-potency **topical corticosteroids** are the first-line treatment for localized cutaneous disease on flexural surfaces.- They reduce the inflammation (T-cell-mediated injury to the **basal layer** of the epidermis) and effectively alleviate symptoms like intense **pruritus** (itching).*Antibiotics*- Lichen planus is a **sterile inflammatory process**, not caused by a bacterial infection, making antibiotics ineffective for treating the underlying pathology.- Antibiotics are reserved for infectious conditions like cellulitis or **secondary bacterial infection** of the lesions, which is not indicated here.*Immunosuppressants*- Systemic **immunosuppressants** (e.g., methotrexate, cyclosporine) are reserved for severe, widespread, or treatment-refractory cases, or extensive subtypes like **erosive oral lichen planus**.- For localized cutaneous disease, the risk profile of systemic immunosuppression does not justify its use over topical therapy.*Anti-fungal*- Anti-fungal agents are used to treat infections caused by fungi, such as **Tinea corporis** (ringworm), which presents with scaly, erythematous plaques, not flat-topped violaceous papules.- Lichen planus is an autoimmune/inflammatory dermatosis; therefore, anti-fungals have no role in its primary management.

Q: A patient presented with itchy lesions, as shown below. What is the diagnosis?

Lichen planus. ***Lichen planus*** - The image displays classic features of lichen planus, which are often described by the **'5 P's'**: **P**ruritic (itchy), **P**olygonal, **P**lanar (flat-topped), **P**urple **P**apules and plaques. - A characteristic sign, though not always clearly visible, is the presence of fine white lines on the surface of the lesions, known as **Wickham's striae**. It is also associated with **Hepatitis C** infection. *Scabies* - Scabies presents with intensely pruritic small papules, vesicles, and pathognomonic **burrows**, which are not seen in the image. The lesions shown are large plaques, not typical for a mite infestation. - The distribution of scabies is characteristic, favoring **finger web spaces**, wrists, axillae, and the genital area, whereas the lesions shown are on a broader surface. *Psoriasis* - Psoriasis typically appears as well-demarcated, erythematous plaques covered with a thick, **silvery-white scale**. The lesions in the image are violaceous and lack the prominent silvery scale. - A key clinical sign in psoriasis is the **Auspitz sign**, where pinpoint bleeding occurs after the scale is removed. Lesions are commonly found on **extensor surfaces** like the elbows and knees. *Warts* - Warts (verruca vulgaris) are caused by the **Human Papillomavirus (HPV)** and present as hyperkeratotic, exophytic papules with a rough, papillomatous surface, unlike the flat-topped lesions in the image. - On close inspection, warts often show thrombosed capillaries appearing as **black dots** (pepper pot sign), which are absent in these lesions.

Question 1

Chloroquine is used in the treatment of which of the following dermatological conditions?

Accepted Answer

Discoid Lupus Erythematosus (DLE)

Answer

Pemphigus

Answer

Psoriasis

Answer

Nummular eczema

Question 2

Acantholysis is characteristic of which of the following conditions?

Accepted Answer

Pemphigus vulgaris

Answer

Pemphigoid

Answer

Erythema multiforme

Answer

Dermatitis herpetiformis

Question 3

In pemphigus, circulating antibodies attack which components?

Accepted Answer

Desmoglein 1 and 3

Answer

Desmoglein 1 and 2

Answer

Desmoglein 1 and 4

Answer

Desmoglein 2 and 4

Question 4

Which of the following antigens are associated with cicatricial pemphigoid?

Accepted Answer

BPAG2 and epiligrin

Answer

HLA DR5 and HLA B8

Answer

HLA DR52 and HLA DR3

Answer

HLA DQB2

Question 5

Desmoplakin is the target antigen in which of the following conditions?

Accepted Answer

Paraneoplastic pemphigus.

Answer

Pemphigus vulgaris.

Answer

Drug induced pemphigus.

Answer

Pemphigus foliaceous.

Question 6

A 72-year-old man is newly diagnosed with bullous pemphigoid. Which of the following is the most appropriate next step in the management?

Accepted Answer

High-dose prednisone (50-100 mg/day)

Answer

Plasmapheresis

Answer

Low-dose prednisone (10-20 mg/day)

Answer

Azathioprine (150 mg/day)

Question 7

Pyoderma gangrenosum is most commonly associated with which of the following conditions?

Accepted Answer

Ulcerative colitis

Answer

Crohn's disease

Answer

Amoebic colitis

Answer

Ischemic colitis

Question 8

What is the percentage of patients with disseminated discoid lupus erythematosus who develop systemic lupus erythematosus?

Accepted Answer

22%

Answer

2%

Answer

52%

Answer

82%

Question 9

A 45-year-old patient presents with itchy, flat-topped, polygonal, violaceous papules on the inner wrists and flexors surfaces of the forearms. The lesions have a characteristic shiny surface and are arranged in a linear pattern. The patient denies any recent medication changes. What is the treatment?

Accepted Answer

Topical steroids

Answer

Anti-fungal

Answer

Antibiotics

Answer

Immunosuppressants

Question 10

A patient presented with itchy lesions, as shown below. What is the diagnosis?

Accepted Answer

Lichen planus

Answer

Scabies

Answer

Psoriasis

Answer

Warts

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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