Autoimmune Skin Diseases Practice Questions

Q: Gottron papules are seen in:

Dermatomyositis. ***Dermatomyositis*** - **Gottron papules** are pathognomonic for **dermatomyositis**, presenting as violaceous, flat-topped papules or plaques over the extensor surfaces of the **metacarpophalangeal (MCP)** and **interphalangeal (IP)** joints. - They are one of the characteristic cutaneous manifestations, often accompanied by **heliotrope rash** and **proximal muscle weakness**. *Behcet's syndrome* - Characterized by **recurrent oral and genital aphthous ulcers**, **ocular inflammation**, and skin lesions like **erythema nodosum**, but not Gottron papules. - It is a **vasculitis** affecting various organs, primarily due to immune dysregulation. *Sarcoidosis* - A **multisystem granulomatous disorder** that can affect the skin with lesions such as **lupus pernio** or **erythema nodosum**, but not Gottron papules. - It is often associated with pulmonary involvement and can cause **hypercalcemia**. *Scleroderma* - Also known as **systemic sclerosis**, is characterized by **skin thickening** and **fibrosis** due to excessive collagen deposition. - Common skin manifestations include **Raynaud phenomenon**, **sclerodactyly**, and **telangiectasias**, distinct from Gottron papules.

Q: Which skin manifestation is characteristically seen in dermatomyositis?

Gottron papules. ***Gottron papules*** - **Gottron papules** are raised, erythematous, or violaceous plaques over the **extensor surfaces of the metacarpophalangeal (MCP)** and **interphalangeal (IP)** joints. - They are considered **pathognomonic** (diagnostic) for dermatomyositis and are the most universally accepted characteristic cutaneous marker of the condition. *Heliotrope rash* - The **heliotrope rash** is a characteristic violaceous (purple-red) discoloration on the upper eyelids, often associated with **periorbital edema**. - While highly characteristic of **dermatomyositis**, Gottron papules are more universally accepted as the most pathognomonic feature. *Butterfly rash* - The **butterfly rash** (malar rash) is a classic manifestation of **systemic lupus erythematosus (SLE)**, characterized by redness over the cheeks and nasal bridge, sparing the nasolabial folds. - It is not typically seen in dermatomyositis and suggests a different underlying autoimmune condition. *Shawl sign* - The **shawl sign** refers to a diffuse, flat, erythematous rash over the **shoulders, upper back, and posterior neck**, often exacerbated by sun exposure. - Although seen in dermatomyositis, it is less specific than Gottron papules, which are directly diagnostic of the condition.

Q: Which finding is most specific for pemphigus vulgaris?

Intercellular IgG deposits. ***Intercellular IgG deposits*** - **Direct immunofluorescence** (DIF) showing **intercellular IgG deposits** in the epidermis is the **gold standard diagnostic finding** and most specific for pemphigus vulgaris. This reflects the presence of autoantibodies targeting **desmogleins 1 and 3**, key components of desmosomes. - These antibodies disrupt cell-to-cell adhesion, leading to the characteristic **flaccid bullae** seen clinically. - This immunopathological finding has near 100% sensitivity and specificity for pemphigus vulgaris. *Suprabasal acantholysis* - While **suprabasal acantholysis** is the most characteristic **light microscopic (H&E) finding** in pemphigus vulgaris, it is a morphological consequence of the autoantibody attack and not as specific as the immunofluorescence pattern. - **Acantholysis** refers to the loss of cohesion between keratinocytes, leading to the formation of intraepidermal blisters with a characteristic "row of tombstones" appearance at the base. - This finding can occasionally be seen in other acantholytic conditions, making it less specific than DIF. *Granular IgA deposits* - **Granular IgA deposits** along the dermoepidermal junction are characteristic of **dermatitis herpetiformis**, a pruritic papulovesicular disease associated with celiac disease. - These deposits are typically found in the dermal papillae and are distinct from the intercellular IgG seen in pemphigus. *Basement membrane thickening* - **Basement membrane thickening** is a non-specific finding that can be seen in various chronic skin conditions, including **lichen sclerosus et atrophicus** or in some forms of **lupus erythematosus**. - It is not a primary or specific feature of pemphigus vulgaris, which is characterized by intraepidermal blistering due to loss of cell-to-cell adhesion.

Q: Which skin disorder is associated with gluten sensitivity?

Dermatitis herpetiformis. ***Dermatitis herpetiformis*** - This condition is characterized by **itchy, blistering skin lesions** that typically appear on the elbows, knees, and buttocks. - It is strongly associated with **celiac disease** (gluten-sensitive enteropathy) and improves significantly with a **gluten-free diet**. *Pemphigus vulgaris* - Pemphigus vulgaris is an **autoimmune blistering disease** caused by antibodies against **desmogleins** in the epidermis, leading to intraepidermal blistering. - Its pathogenesis is not related to gluten sensitivity, but rather to a breakdown of **cell adhesion** in the skin. *Psoriasis* - Psoriasis is a **chronic inflammatory skin disease** characterized by red, scaly patches (plaques) due to rapid skin cell turnover. - While it has an autoimmune component, it is not directly linked to **gluten sensitivity**, though some patients report symptom improvement with dietary changes. *Scleroderma* - Scleroderma (systemic sclerosis) is a **chronic autoimmune disease** that causes **fibrosis** (hardening) of the skin and internal organs. - Its pathophysiology involves **collagen overproduction** and vascular dysfunction, with no known association with gluten sensitivity.

Q: Which of the following is NOT associated with erythema nodosum?

Pemphigus vulgaris. ***Pemphigus vulgaris*** - **Pemphigus vulgaris** is an **autoimmune blistering disease** that affects the skin and mucous membranes, characterized by flaccid bullae, not subcutaneous nodules. - Its pathophysiology involves **autoantibodies** against **desmoglein 1 and 3**, leading to **acantholysis**, which is distinct from the inflammatory changes seen in erythema nodosum. *Tuberculosis* - **Tuberculosis (TB)** is a common infectious cause of **erythema nodosum**, especially in regions with high TB prevalence. - The development of erythema nodosum in TB is often considered a **hypersensitivity reaction** to mycobacterial antigens. *Sarcoidosis* - **Sarcoidosis** is a systemic granulomatous disease, and **erythema nodosum** can be a prominent cutaneous manifestation, particularly in **Löfgren's syndrome**. - Its presence with **bilateral hilar lymphadenopathy** and **arthralgia** is highly suggestive of acute sarcoidosis. *Leprosy* - **Leprosy**, caused by *Mycobacterium leprae*, can be associated with **erythema nodosum leprosum (ENL)**, which is a type 2 lepra reaction. - **ENL** involves the formation of painful, tender, inflamed nodules that resemble erythema nodosum and is linked to elevated immune complex deposition.

Q: Which histological finding is most specific for pemphigus vulgaris?

Row of tombstones. ***Row of tombstones*** - This characteristic histological finding in **pemphigus vulgaris** refers to the appearance of a single layer of basal cells still attached to the basement membrane, resembling a **row of tombstones**, after the detachment of suprabasal epidermal cells. - It signifies **acantholysis** (loss of cell-to-cell adhesion) occurring just above the basal layer. *Basement membrane thickening* - This finding is more characteristic of conditions like **lichen sclerosus** or some chronic inflammatory dermatoses, and is not specific for pemphigus vulgaris. - It does not directly reflect the underlying immune-mediated acantholysis seen in pemphigus. *Granular IgA deposits* - **Granular IgA deposits** along the dermal-epidermal junction are the hallmark of **dermatitis herpetiformis**. - Pemphigus vulgaris is characterized by IgG autoantibodies, not IgA, targeting desmogleins. *IgG linear deposits* - **Linear IgG deposits** along the dermal-epidermal junction are characteristic of **bullous pemphigoid**, not pemphigus vulgaris. - In pemphigus vulgaris, IgG deposits are typically found in a **chicken-wire pattern** intercellularly within the epidermis.

Q: A 40-year-old man presents with thickened, erythematous skin exhibiting a cobblestone appearance on the lower legs. What is the most likely diagnosis?

Pretibial myxedema. ***Pretibial myxedema*** * **Pretibial myxedema** presents with **thickened, erythematous skin** on the lower legs, often described as having an "orange peel" or **cobblestone appearance**. * It is specifically associated with **Graves' disease** (hyperthyroidism) due to the deposition of hyaluronic acid and chondroitin sulfate. *Lichen planus* * **Lichen planus** typically manifests as **pruritic, purple, polygonal papules and plaques** (the "5 Ps") rather than thickened, cobblestoned skin. * It commonly affects the wrists, ankles, and oral mucosa, with a different characteristic morphology. *Venous stasis dermatitis* * **Venous stasis dermatitis** also affects the lower legs but presents with **reddish-brown discoloration**, **scaling**, itching, and sometimes ulceration due to chronic venous insufficiency. * The skin changes are more indicative of inflammation and poor circulation, not the distinct thickening or cobblestone texture of myxedema. *Chronic plaque psoriasis* * **Chronic plaque psoriasis** is characterized by well-demarcated, **erythematous plaques** covered with **silvery scales**, primarily affecting extensor surfaces (elbows, knees, scalp). * While it causes thickened skin, the appearance is scaly and not typically described as cobblestone or specifically located only in the pretibial area without other psoriatic manifestations.

Q: A 30-year-old male presents with flaccid bullae on an erythematous base and erosions over the oral mucous membrane. What is the most likely finding on an immunofluorescent examination of the skin biopsy of this patient?

Suprabasal deposition. ***Suprabasal deposition*** - The clinical presentation of **flaccid bullae on an erythematous base** and **oral erosions** in a young male is highly suggestive of **pemphigus vulgaris**. - **Pemphigus vulgaris** is characterized by **acantholysis** leading to separation of keratinocytes above the basal layer (suprabasal clefting), with **immunofluorescent examination** typically showing **IgG deposition** in a **fishnet or intercellular pattern** around keratinocytes in the **suprabasal epidermis**. *Subcorneal deposition* - **Subcorneal deposition** of antibodies is characteristic of diseases like **pemphigus foliaceus** or **subcorneal pustular dermatosis**. - **Pemphigus foliaceus** presents with more superficial, crusted erosions without mucosal involvement, unlike the described deep bullae and oral lesions. *Epidermal deposition* - **Epidermal deposition** is too general and non-specific, as it could refer to any level within the epidermis. - While pemphigus vulgaris does show antibody deposition within the epidermis, the specific **suprabasal location** is the key diagnostic feature that distinguishes it from other blistering disorders. *Subepidermal deposition* - **Subepidermal deposition** indicates antibody deposition at the **dermal-epidermal junction (basement membrane zone)**, typically seen in **bullous pemphigoid** or **dermatitis herpetiformis**. - These conditions present with **tense bullae** (not flaccid) due to the deeper level of splitting, and show **linear IgG and C3 deposition** at the BMZ on immunofluorescence, rather than the intercellular pattern seen in pemphigus.

Q: A 30-year-old woman presents with a non-healing ulcer on her lower leg. A biopsy reveals neutrophilic infiltration. Which condition is likely?

Pyoderma gangrenosum. ***Pyoderma gangrenosum*** - This condition is characterized by rapidly enlarging, painful, **necrotic ulcers** with undermined violaceous borders, often triggered by trauma (pathergy). - Histologically, it shows a dense **neutrophilic infiltrate** without vasculitis, fitting the biopsy findings. *Basal cell carcinoma* - This is a common **skin cancer** that typically presents as a pearly nodule with rolled borders and telangiectasias, not usually a rapidly evolving necrotic ulcer. - Histology shows nests of basaloid cells with peripheral palisading, not primarily a neutrophilic infiltrate. *Squamous cell carcinoma* - This skin cancer often presents as a **scaly, erythematous patch, nodule, or ulcer**, especially in sun-exposed areas. - While it can ulcerate, the biopsy would show atypical keratinocytes with varying degrees of differentiation, not predominantly neutrophilic infiltration. *Kaposi sarcoma* - This is a **vascular cancer** associated with human herpesvirus 8 (HHV-8), commonly presenting as violaceous patches, plaques, or nodules. - Histology reveals a proliferation of spindle cells, vascular slits, and extravasated red blood cells, not a prominent neutrophilic infiltrate.

Q: A 50-year-old male presents with a painful ulcer on his leg. The ulcer has an undermined border and purulent discharge, and he has a history of inflammatory bowel disease. What is the most likely diagnosis?

Pyoderma gangrenosum. ***Pyoderma gangrenosum*** - The classic presentation includes a rapidly progressive, painful ulcer with an **undermined violaceous border** and **purulent exudate**. - A strong association with **inflammatory bowel disease** (e.g., Crohn's disease, ulcerative colitis) is a key diagnostic clue. *Venous ulcer* - Typically found around the **malleoli**, often with a **shallow base**, irregular borders, and associated signs of venous insufficiency like edema and hyperpigmentation. - While they can be painful and purulent if infected, the **undermined border** and strong IBD link point away from this. *Arterial ulcer* - Characteristically located on the **distal extremities** (toes, foot), with a **"punched-out" appearance**, pale base, and often painful, especially at night. - They are associated with **peripheral arterial disease** and cool, pulseless limbs, which are not described here. *Diabetic ulcer* - Usually painless (due to neuropathy), found on **pressure points** of the foot, often with a **calloused rim**. - While they can become secondarily infected and purulent, the defining features like **painful undermined border** and **IBD association** are inconsistent.

Question 1

Gottron papules are seen in:

Accepted Answer

Dermatomyositis

Answer

Behcet's syndrome

Answer

Sarcoidosis

Answer

Scleroderma

Question 2

Which skin manifestation is characteristically seen in dermatomyositis?

Accepted Answer

Gottron papules

Answer

Butterfly rash

Answer

Shawl sign

Answer

Heliotrope rash

Question 3

Which finding is most specific for pemphigus vulgaris?

Accepted Answer

Intercellular IgG deposits

Answer

Granular IgA deposits

Answer

Suprabasal acantholysis

Answer

Basement membrane thickening

Question 4

Which skin disorder is associated with gluten sensitivity?

Accepted Answer

Dermatitis herpetiformis

Answer

Pemphigus vulgaris

Answer

Psoriasis

Answer

Scleroderma

Question 5

Which of the following is NOT associated with erythema nodosum?

Accepted Answer

Pemphigus vulgaris

Answer

Tuberculosis

Answer

Sarcoidosis

Answer

Leprosy

Question 6

Which histological finding is most specific for pemphigus vulgaris?

Accepted Answer

Row of tombstones

Answer

Basement membrane thickening

Answer

Granular IgA deposits

Answer

IgG linear deposits

Question 7

A 40-year-old man presents with thickened, erythematous skin exhibiting a cobblestone appearance on the lower legs. What is the most likely diagnosis?

Accepted Answer

Pretibial myxedema

Answer

Lichen planus

Answer

Venous stasis dermatitis

Answer

Chronic plaque psoriasis

Question 8

A 30-year-old male presents with flaccid bullae on an erythematous base and erosions over the oral mucous membrane. What is the most likely finding on an immunofluorescent examination of the skin biopsy of this patient?

Accepted Answer

Suprabasal deposition

Answer

Subcorneal deposition

Answer

Epidermal deposition

Answer

Subepidermal deposition

Question 9

A 30-year-old woman presents with a non-healing ulcer on her lower leg. A biopsy reveals neutrophilic infiltration. Which condition is likely?

Accepted Answer

Pyoderma gangrenosum

Answer

Basal cell carcinoma

Answer

Squamous cell carcinoma

Answer

Kaposi sarcoma

Question 10

A 50-year-old male presents with a painful ulcer on his leg. The ulcer has an undermined border and purulent discharge, and he has a history of inflammatory bowel disease. What is the most likely diagnosis?

Accepted Answer

Pyoderma gangrenosum

Answer

Venous ulcer

Answer

Arterial ulcer

Answer

Diabetic ulcer

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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