Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases Indian Medical PG Practice Questions and MCQs

Question 61: Which of the following autoantibodies is most suggestive of subacute cutaneous lupus erythematosus?

A. anti ds DNA
B. anti Ro (Correct Answer)
C. anti La
D. U1 RNP

Explanation: **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.

Question 62: Immunofluorescence is seen at the basement membrane as a patchy distribution in which of the following conditions?

A. Lichen Planus
B. Pemphigus
C. Pemphigoid (Correct Answer)
D. Lupus erythematosus

Explanation: **Explanation:** The question focuses on the Direct Immunofluorescence (DIF) patterns of autoimmune and inflammatory skin diseases. **Why Pemphigoid is Correct:** In **Bullous Pemphigoid**, autoantibodies (IgG and C3) target the hemidesmosomes (BP180 and BP230) at the dermo-epidermal junction. On DIF, this manifests as a **linear, continuous, or patchy/shaggy deposition** of IgG and C3 along the **basement membrane zone (BMZ)**. The term "patchy" or "shaggy" is often used to describe the irregular intensity of the linear band seen in subepidermal blistering diseases. **Analysis of Incorrect Options:** * **Lichen Planus:** DIF typically shows **shaggy** deposits of **fibrinogen** along the BMZ and globular deposits of IgM (Cytoid/Civatte bodies) in the papillary dermis. It is not primarily characterized by patchy IgG at the BMZ. * **Pemphigus:** This is an intraepidermal disease. DIF shows a characteristic **"fishnet" or "lace-like" pattern** of IgG and C3 in the intercellular spaces of the epidermis, not at the basement membrane. * **Lupus Erythematosus (SLE/DLE):** While LE shows a "Lupus Band" (granular IgG/IgM at the BMZ), it is classically described as a **continuous granular band**, rather than the patchy distribution characteristic of the pemphigoid group. **NEET-PG High-Yield Pearls:** * **Bullous Pemphigoid:** Linear BMZ pattern; Salt-split skin study shows localization to the **roof** of the blister. * **Epidermolysis Bullosa Acquisita (EBA):** Also shows linear BMZ pattern, but localization is to the **floor** of the blister. * **Dermatitis Herpetiformis:** Characterized by **granular IgA** deposits at the tips of dermal papillae. * **Pemphigus Vulgaris:** IgG targets **Desmoglein 3** (mucosal) and **Desmoglein 1** (skin).

Question 63: The Band test is indicated in which of the following conditions?

A. Rheumatoid arthritis
B. Systemic lupus erythematosus (Correct Answer)
C. Scleroderma
D. Polyarteritis nodosa

Explanation: 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.

Question 64: Which of the following is not seen in Behçet's syndrome?

A. Genital ulcers
B. Uveitis
C. Oral ulcers
D. Pyoderma gangrenosum (Correct Answer)

Explanation: **Explanation:** Behçet’s syndrome is a chronic, multisystem inflammatory disorder characterized by systemic vasculitis. The diagnosis is primarily clinical, based on the **International Study Group (ISG) criteria**, which require the presence of recurrent oral ulcers plus any two of the following: recurrent genital ulcers, eye lesions, skin lesions, or a positive pathergy test. **Why Pyoderma Gangrenosum (PG) is the correct answer:** While Behçet’s syndrome is associated with various cutaneous manifestations, **Pyoderma gangrenosum** is not a characteristic feature. PG is a neutrophilic dermatosis typically associated with Inflammatory Bowel Disease (IBD), Rheumatoid Arthritis, and hematological malignancies. In Behçet’s, the classic skin lesions are **erythema nodosum-like lesions**, pseudofolliculitis, acneiform nodules, and palpable purpura. **Analysis of incorrect options:** * **Oral Ulcers (Option C):** These are the hallmark and usually the first sign of the disease. They are painful, recurrent, and must occur at least three times in a 12-month period for diagnosis. * **Genital Ulcers (Option A):** These are highly specific for Behçet’s. Unlike oral ulcers, they are deeper and often heal with scarring. * **Uveitis (Option B):** Ocular involvement occurs in about 70% of patients. **Bilateral posterior uveitis** is the most common serious complication and can lead to blindness. **Clinical Pearls for NEET-PG:** * **Pathergy Test:** A unique diagnostic feature where a sterile pustule forms 24–48 hours after a skin prick with a 20-gauge needle. * **HLA Association:** Strongly linked with **HLA-B51**. * **Hypopyon:** The presence of inflammatory cells in the anterior chamber of the eye (sterile pus) is a classic ocular finding. * **Magic Syndrome:** A rare variant showing features of both Behçet’s and Relapsing Polychondritis (Mouth And Genital Ulcers with Inflamed Cartilage).

Question 65: Adenoma sebaceum and shagreen patches are seen in which of the following conditions?

A. Neurofibromatosis I
B. Tuberous sclerosis (Correct Answer)
C. Von Hippel-Lindau disease
D. Li-Fraumeni syndrome

Explanation: **Explanation:** **Tuberous Sclerosis Complex (TSC)**, also known as Bourneville’s disease, is an autosomal dominant neurocutaneous syndrome caused by mutations in the **TSC1 (Hamartin)** or **TSC2 (Tuberin)** genes. The classic clinical triad (Vogt’s triad) includes seizures, mental retardation, and adenoma sebaceum. * **Adenoma Sebaceum:** Despite the name, these are actually **facial angiofibromas**. They typically appear as reddish papules in a butterfly distribution over the nose and cheeks. * **Shagreen Patches:** These are connective tissue nevi (collagenomas) usually found in the lumbosacral region, presenting as firm, leathery, "orange-peel" textured plaques. **Analysis of Incorrect Options:** * **Neurofibromatosis I (NF-1):** Characterized by Lisch nodules, Café-au-lait spots (6 or more), and neurofibromas. It does not feature shagreen patches. * **Von Hippel-Lindau (VHL):** Associated with hemangioblastomas of the retina and cerebellum, and renal cell carcinoma. It lacks the specific cutaneous markers of TSC. * **Li-Fraumeni Syndrome:** A cancer predisposition syndrome caused by p53 mutations, leading to various internal malignancies (sarcomas, breast cancer) rather than specific hamartomatous skin lesions. **High-Yield Clinical Pearls for NEET-PG:** * **Ash-leaf spots:** Hypopigmented macules; often the *earliest* sign of TSC. * **Koenen tumors:** Periungual fibromas appearing around the nails. * **Confetti lesions:** Multiple tiny hypopigmented macules on the limbs. * **Systemic findings:** Cardiac rhabdomyomas (often regress), Renal Angiomyolipomas (AML), and Giant Cell Astrocytomas (SEGA).

Question 66: What is the commonest cutaneous eruption in Systemic Lupus Erythematosus?

A. Palmar erythema
B. Discoid lesions
C. Erythema of light-exposed areas (Correct Answer)
D. Diffuse morbilliform erythema

Explanation: **Explanation:** Systemic Lupus Erythematosus (SLE) is a multisystem autoimmune disease characterized by a wide array of dermatological manifestations. **Why Option C is Correct:** The most common cutaneous eruption in SLE is **photosensitivity**, manifesting as **erythema of light-exposed areas**. This includes the classic **malar rash** (butterfly rash), which is a fixed erythema over the cheeks and bridge of the nose, typically sparing the nasolabial folds. Photosensitivity is reported in approximately 70-90% of SLE patients. The underlying mechanism involves UV-induced apoptosis of keratinocytes, leading to the exposure of nuclear antigens (like Ro/SSA) to the immune system, triggering an inflammatory response. **Analysis of Incorrect Options:** * **A. Palmar erythema:** While it can occur in SLE (often as part of vasculitis or associated pregnancy/liver issues), it is non-specific and much less common than photosensitivity. * **B. Discoid lesions:** These are the hallmark of Chronic Cutaneous Lupus Erythematosus (CCLE). While 10-15% of SLE patients may have discoid lesions, they are not the *most common* eruption in the systemic form. * **D. Diffuse morbilliform erythema:** This is a non-specific maculopapular rash often seen in drug eruptions or viral exanthems. While SLE can present with a generalized maculopapular rash, it is less frequent than localized malar/photosensitive erythema. **High-Yield Clinical Pearls for NEET-PG:** * **Malar Rash:** Sparing of the **nasolabial folds** is a key clinical differentiator from seborrheic dermatitis or rosacea. * **Lupus Hair:** Characterized by thin, frizzy hair at the frontal hairline; a common sign of systemic activity. * **Most Specific Test:** Anti-dsDNA and Anti-Smith antibodies. * **Most Sensitive Test:** ANA (Antinuclear Antibody). * **Histopathology:** The "Lupus Band Test" shows linear IgG/C3 deposits at the dermo-epidermal junction.

Question 67: What is the best serological test for subacute cutaneous lupus erythematosus?

A. dsDNA antibodies
B. Anti-Jo-1 antibody
C. Anti-Ro/SSA antibodies (Correct Answer)
D. Anti-histone antibodies

Explanation: **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/SSA is the correct answer:** The hallmark of SCLE is its strong association with **Anti-Ro/SSA antibodies** (present in ~75–90% of cases) and, to a lesser extent, Anti-La/SSB antibodies. These antibodies are pathogenic in inducing photosensitivity. SCLE is also the classic presentation of **Drug-Induced SCLE** (commonly caused by HCTZ, Terbinafine, and Calcium Channel Blockers) and is the primary antibody profile seen in **Neonatal Lupus**. **Analysis of Incorrect Options:** * **A. dsDNA antibodies:** Highly specific for **Systemic Lupus Erythematosus (SLE)** and correlate with disease activity and lupus nephritis, but they are typically negative in pure SCLE. * **B. Anti-Jo-1 antibody:** The most common anti-synthetase antibody associated with **Dermatomyositis**, characterized by "Mechanic’s hands," interstitial lung disease, and arthritis. * **D. Anti-histone antibodies:** The classic marker for **Drug-Induced SLE** (e.g., caused by Hydralazine, Procainamide, Isoniazid). Note: Drug-induced *SLE* has anti-histone antibodies, but drug-induced *SCLE* has anti-Ro antibodies. **High-Yield Clinical Pearls for NEET-PG:** * **SCLE Morphology:** Annular/polycyclic or Psoriasiform lesions; heals **without scarring** (unlike Discoid Lupus). * **HLA Association:** Strongly linked to **HLA-DR3**. * **Neonatal Lupus:** Caused by transplacental transfer of Anti-Ro/SSA; most common complication is **congenital heart block**. * **ANA:** Usually positive in SCLE, but Anti-Ro is the most specific serological marker for this subtype.

Question 68: Gottron's papules or sign is seen in which of the following conditions?

A. Dermatomyositis (Correct Answer)
B. Multiple myeloma
C. Acute myeloid leukemia
D. Psoriasis

Explanation: **Explanation:** **Dermatomyositis** is an idiopathic inflammatory myopathy characterized by proximal muscle weakness and distinctive cutaneous findings. **Gottron’s papules** are considered a pathognomonic (highly specific) feature of this condition. They are erythematous to violaceous, flat-topped papules found over the dorsal aspects of the interphalangeal and metacarpophalangeal joints. **Gottron’s sign** refers to similar symmetric violaceous erythema (with or without edema) over the elbows, knees, or medial malleoli. **Analysis of Incorrect Options:** * **Multiple Myeloma:** This plasma cell dyscrasia is associated with skin findings like systemic amyloidosis (e.g., pinch purpura, macroglossia) but not Gottron’s papules. * **Acute Myeloid Leukemia (AML):** Cutaneous manifestations of AML include Leukemia Cutis (nodules/plaques) or Sweet Syndrome (neutrophilic dermatosis), which are clinically distinct from the papules seen in dermatomyositis. * **Psoriasis:** While psoriasis presents with erythematous plaques, they typically feature silvery-white scales and are found on extensor surfaces (elbows/knees) rather than specifically over the small joints of the hands. **High-Yield Clinical Pearls for NEET-PG:** * **Heliotrope Rash:** Violaceous eruption on the upper eyelids with periorbital edema (another pathognomonic sign). * **Shawl Sign & V-Sign:** Erythema over the upper back/shoulders and the anterior chest, respectively. * **Mechanic’s Hands:** Hyperkeratosis and fissuring of the palmar and lateral surfaces of the fingers (associated with Anti-Jo-1 antibodies). * **Malignancy Risk:** Dermatomyositis in adults is frequently a **paraneoplastic syndrome**; always screen for underlying internal malignancies (e.g., ovarian, lung, or GI cancers).

Question 69: Which of the following is NOT typically seen in dermatomyositis?

A. Salmon patch (Correct Answer)
B. Gottron's papules
C. Perioral telangiectasia
D. Mechanic's finger

Explanation: The correct answer is **A. Salmon patch**. ### **Explanation** **Salmon patch** (Nevus simplex) is a common congenital capillary malformation (vascular birthmark) typically found on the nape of the neck (stork bite) or the forehead/eyelids (angel kiss). It is a benign, developmental condition and has no clinical association with **Dermatomyositis**, which is an autoimmune inflammatory myopathy. ### **Analysis of Other Options** * **B. Gottron’s papules:** These are considered **pathognomonic** for dermatomyositis. They are violaceous, lichenoid papules found over the dorsal aspects of the interphalangeal and metacarpophalangeal joints. * **C. Periungual/Perioral telangiectasia:** Dilated capillary loops at the nail folds (periungual) or around the mouth are classic vascular signs of dermatomyositis, reflecting the underlying microangiopathy. * **D. Mechanic’s hands/fingers:** This refers to hyperkeratotic, fissured, "dirty-appearing" scaling on the lateral and palmar aspects of the fingers. It is highly associated with **Anti-synthetase syndrome** (a subset of dermatomyositis) and interstitial lung disease (ILD). ### **High-Yield Clinical Pearls for NEET-PG** * **Heliotrope rash:** Violaceous edema of the upper eyelids (another pathognomonic sign). * **Shawl sign & V-sign:** Poikiloderma (atrophy, telangiectasia, pigmentation) over the upper back/shoulders and the anterior chest, respectively. * **Holster sign:** Poikiloderma on the lateral aspect of the thighs. * **Malignancy:** Dermatomyositis in adults carries a high risk of internal malignancy (e.g., ovarian, lung, breast, GI). * **Key Antibody:** **Anti-Mi-2** is highly specific for dermatomyositis; **Anti-Jo-1** is associated with Mechanic's hands and ILD.

Question 70: Chloroquine is used in the treatment of which of the following dermatological conditions?

A. Discoid Lupus Erythematosus (DLE) (Correct Answer)
B. Pemphigus
C. Psoriasis
D. Nummular eczema

Explanation: **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.

Practice by Chapter

Lupus Erythematosus: Cutaneous Forms

Practice Questions

Lupus Erythematosus: Systemic with Skin Manifestations

Practice Questions

Dermatomyositis

Practice Questions

Scleroderma and Morphea

Practice Questions

Mixed Connective Tissue Disease

Practice Questions

Sjögren's Syndrome: Cutaneous Manifestations

Practice Questions

Relapsing Polychondritis

Practice Questions

Autoimmune Thyroid Disease and the Skin

Practice Questions

Immunobullous Disorders

Practice Questions

Vasculitis

Practice Questions

Diagnostic Methods in Autoimmune Dermatoses

Practice Questions

Management of Autoimmune Skin Diseases

Practice Questions

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