Autoimmune Skin Diseases Practice Questions

Q: A 45-year-old Ulcerative colitis patient presents with multiple painful lesions on both legs. What is the diagnosis?

Pyoderma gangrenosum. ***Pyoderma gangrenosum*** - This patient has **ulcerative colitis**, which is strongly associated with **pyoderma gangrenosum**, a neutrophilic dermatosis. - The image shows characteristic **painful, rapidly expanding ulcers** with violaceous, undermined borders, typical of pyoderma gangrenosum. *Febrile neutropenic dermatosis* - This condition (also known as **Sweet syndrome**) occurs in patients with **neutropenia** and **fever**, presenting with painful erythematous plaques or nodules. - While systemic illness like ulcerative colitis can predispose to skin conditions, the specific presentation and lack of mentioned neutropenia make this less likely. *Necrotizing fasciitis* - **Necrotizing fasciitis** is a rapidly progressive, life-threatening infection of the deep fascia and subcutaneous tissue, typically presenting with severe pain, erythema, swelling, and crepitus. - The lesions in the image appear to be chronic ulcers with specific borders rather than acute, rapidly spreading infection of necrotizing fasciitis. *Granulomatosis with polyangiitis* - Also known as **Granulomatosis with polyangiitis (GPA)**, formerly **Wegener's granulomatosis**, this is an autoimmune vasculitis primarily affecting the respiratory tract and kidneys, and can cause skin lesions such as palpable purpura, nodules, or ulcers. - While skin lesions can occur, the characteristic features of **pyoderma gangrenosum** and its strong association with inflammatory bowel disease make it a more probable diagnosis in this context.

Q: A 42 year old man presented with recurrent oral ulcers since one year, episodes of redness of eye and genital ulcers. Which one of the following tests is of diagnostic value?

Pathergy test. ***Pathergy test*** - The constellation of **recurrent oral and genital ulcers** along with **ocular inflammation (redness of eye)** is highly suggestive of **Behçet's disease**. - The **pathergy test** assesses for a hyper-reactivity of the skin to needle prick, which is characteristic of Behçet's disease and thus of diagnostic value. *Drug-sensitivity test* - This test is primarily used to identify allergic reactions or sensitivities to specific medications. - It would not be indicated for diagnosing a systemic inflammatory condition like Behçet's disease. *Patch test* - A **patch test** is used to identify substances that cause allergic contact dermatitis by applying potential allergens to the skin. - It is not relevant for the diagnosis of Behçet's disease, which involves inflammatory rather than allergic reactions. *Mantoux test* - The **Mantoux test** (tuberculin skin test) is used to screen for **tuberculosis infection** [1]. - This patient's symptoms are not consistent with tuberculosis, and the Mantoux test has no role in diagnosing Behçet's disease [2].

Q: Which one of the following is NOT true of Pyoderma gangrenosum?

Cultures often show Gram positive Staphylococci. ***Cultures often show Gram positive Staphylococci*** - Pyoderma gangrenosum is a **sterile inflammatory dermatosis**, meaning that the ulcers are not caused by bacterial infection. - While secondary infection can occur, the primary lesion itself is **non-infectious**, and therefore, routine cultures of the ulcer base would typically be negative for primary pathogens like *Staphylococci*. *It is often secondary to heightened immunological reactivity from another disease process* - Pyoderma gangrenosum is well-known for its association with underlying systemic conditions, particularly **inflammatory bowel disease**, **rheumatoid arthritis**, and certain **hematologic malignancies**. - Its pathogenesis is thought to involve **dysregulated neutrophils** and an underlying autoimmune or autoinflammatory process. *Lesions generally respond to steroids* - **Corticosteroids** are the first-line treatment for Pyoderma gangrenosum, used to reduce inflammation and promote healing. - Both topical and systemic corticosteroids, such as **prednisone**, are effective in managing the condition. *It is characterized by cutaneous ulceration with purple undermined edges* - The classic presentation of Pyoderma gangrenosum is a rapidly evolving, painful, **necrotic ulcer** with a characteristic **violaceous (purple) undermined border**. - This distinctive appearance helps differentiate it from other types of skin ulcers.

Q: A 32-year-old woman presents with recurrent genital ulcers. She was previously diagnosed with genital herpes based on clinical appearance, but current PCR testing for HSV is negative. She also reports occasional painful mouth sores. Serological tests for syphilis are negative. What is the most likely diagnosis?

Behçet's syndrome. Behçet's syndrome - Recurrent genital ulcers that are often painful and heal with scarring, in the absence of HSV or other STIs, are characteristic of Behçet's syndrome. - While other systemic symptoms such as oral ulcers, uveitis, and skin lesions (e.g., erythema nodosum) are common, the diagnosis can be made based on recurrent genital ulcers and the exclusion of other causes. Fixed drug eruption - A fixed drug eruption typically produces a solitary or a few localized skin or mucosal lesions que recur at the same site, usually within hours of drug re-exposure. - While it can cause genital ulcers, it's less likely to present with recurrent ulcers without a clear history of drug exposure or at multiple sites. Crohn's disease - Genital ulcers can occur in Crohn's disease, often as a manifestation of perianal disease or metastatic Crohn's, but they are typically associated with prominent gastrointestinal symptoms (e.g., chronic diarrhea, abdominal pain, weight loss). - The absence of other symptoms makes Crohn's disease less likely in this isolated presentation. Aphthous ulcers - Aphthous ulcers primarily affect the oral mucosa and are not typically found on the genitals [1]. - While Behçet's syndrome does include recurrent oral aphthous ulcers in its diagnostic criteria, genital aphthous ulcers as a solitary finding are not common without other associated symptoms or conditions [1].

Q: A patient presents with skin lesions and erosions on the buccal mucosa. The immunofluorescence image is shown. What is the most likely diagnosis?

Pemphigus vulgaris. ***Pemphigus vulgaris*** - The combination of **flaccid blisters/erosions** on the skin and **buccal mucosal lesions** is characteristic of pemphigus vulgaris. The image showing **intercellular IgG deposits** (a "chicken wire" pattern) in the epidermis confirms the diagnosis on immunofluorescence. - Pemphigus vulgaris is an **autoimmune blistering disease** caused by autoantibodies against **desmoglein 1 and 3**, leading to acantholysis (loss of cell adhesion) within the epidermis. *Bullous pemphigoid* - This condition typically presents with **tense bullae** that are less prone to rupture, and **mucosal involvement is rare**. - Immunofluorescence in bullous pemphigoid shows **linear IgG and C3 deposits at the dermoepidermal junction**, not an intercellular epidermal pattern. *Linear IgA disease* - Characterized by **linear IgA deposition along the basement membrane zone** on direct immunofluorescence. - Clinically, it presents with **blisters** that can be variable in appearance, but the pathognomonic immunofluorescence pattern is distinct. *Dermatitis herpetiformis* - Presents with very **pruritic vesicles and papules**, primarily on extensor surfaces, and is strongly associated with **celiac disease**. - Direct immunofluorescence reveals **granular IgA deposits in the dermal papillae**, which is distinct from the intercellular IgG pattern seen here.

Q: Identify the diagnosis based on the dermatology immunofluorescence (IF) image provided.

Dermatitis herpetiformis. ***Dermatitis herpetiformis*** - The immunofluorescence image shows **granular IgA deposits** at the **dermal papillae region**, which is characteristic of dermatitis herpetiformis. - This condition is strongly associated with **celiac disease** and presents with intensely pruritic papules and vesicles. *Pemphigus vulgaris* - Immunofluorescence in pemphigus vulgaris typically shows a **fishnet pattern** of IgG deposits throughout the **epidermis**, reflecting antibodies against desmoglein 3 and 1. - This pattern is an intercellular deposition, not granular at the dermal papillae. *Pemphigus foliaceus* - Similar to pemphigus vulgaris, pemphigus foliaceus also exhibits **intercellular IgG deposits** in the epidermis, but it is usually more superficial, targeting desmoglein 1. - The image does not show this intercellular epidermal staining. *Bullous pemphigoid* - Bullous pemphigoid is characterized by **linear IgG and C3 deposits along the dermal-epidermal junction** (basement membrane zone). - The image distinctly shows granular IgA, not linear IgG/C3, and specifically in the dermal papillae.

Q: A 30-year-old woman presents with flaccid bullae on her skin that are easy to rupture. A biopsy of the lesion reveals a suprabasal split. What is the most likely diagnosis?

Pemphigus vulgaris. ***Pemphigus vulgaris*** - Characterized by **flaccid bullae** that are easily ruptured, and a classic histological finding of a **suprabasal split** in the epidermis, indicating acantholysis just above the basal layer. - Mucosal involvement is common, and the positive **Nikolsky sign** (epidermal detachment with lateral pressure) is often present, which is typical for pemphigus vulgaris due to the superficial nature of the blistering. - The combination of **flaccid bullae + suprabasal split** is pathognomonic for pemphigus vulgaris. *Erythema multiforme* - Typically presents with **targetoid lesions** (concentric rings of erythema) and is often associated with infections, particularly herpes simplex virus (HSV). - Histologically, it shows **interface dermatitis** with vacuolar degeneration of basal cells and scattered necrotic keratinocytes, not a suprabasal split or acantholysis. *Pemphigus vegetans* - A rare variant of pemphigus vulgaris, it presents with **vegetating plaques** in intertriginous areas (axillae, groin), which are eroded but not primarily flaccid bullae covering wide areas. - While it also involves a suprabasal split at the same level as pemphigus vulgaris, the clinical presentation of vegetating plaques rather than widespread flaccid bullae helps differentiate it. *Pemphigus foliaceous* - This autoimmune blistering disease features very **superficial bullae** that rupture so easily they typically present as erosions, crusts, and scaling rather than intact blisters. - Histologically, it shows a **subcorneal or granular layer split** (more superficial than pemphigus vulgaris), not the deeper suprabasal split seen in this patient's biopsy. - Mucosal involvement is **rare** in pemphigus foliaceous, unlike pemphigus vulgaris.

Q: A 25-year-old woman presents with multiple tense bullae on her arms and legs that developed over the past week. She reports taking amoxicillin for a sore throat 2 weeks ago. Skin biopsy shows subepidermal bulla formation with linear IgA deposits along the basement membrane. Which of the following is the most appropriate treatment?

Dapsone. ***Dapsone*** - The presentation of **tense bullae**, subepidermal bulla formation on biopsy, and linear IgA deposits along the basement membrane zone is characteristic of **linear IgA bullous dermatosis (LABD)**. - **Dapsone** is the first-line and most effective treatment for LABD due to its anti-inflammatory and immunomodulatory properties and ability to interfere with neutrophil chemotaxis. - Important to note that LABD can be **drug-induced**, with antibiotics (including penicillins like amoxicillin) being common triggers. *Topical steroids* - While topical steroids can provide some symptomatic relief for mild, localized lesions, they are generally **insufficient for widespread or severe bullous eruptions** like the one described. - They do not address the underlying **autoimmune pathology** of LABD effectively enough as a primary monotherapy for this presentation. *Oral antibiotics* - Oral antibiotics are used to treat bacterial infections, but this patient's condition is an **autoimmune blistering disease**, not a bacterial infection. - Although the patient took amoxicillin recently (which actually may have **triggered** the LABD), additional antibiotic treatment for LABD itself is not indicated unless there's a secondary bacterial infection of the bullae. *Acyclovir* - **Acyclovir** is an antiviral medication used to treat herpes simplex virus (HSV) or varicella-zoster virus (VZV) infections. - The described condition is an **autoimmune bullous disease**, not a viral infection, and thus acyclovir would be ineffective. - The **tense bullae** and **linear IgA deposits** clearly distinguish this from viral vesiculobullous eruptions.

Question 1

A 45-year-old Ulcerative colitis patient presents with multiple painful lesions on both legs. What is the diagnosis?

Accepted Answer

Pyoderma gangrenosum

Answer

Febrile neutropenic dermatosis

Answer

Necrotizing fasciitis

Answer

Granulomatosis with polyangiitis

Question 2

A 25-year-old lady presents with painful blisters in oral mucosa and skin. Direct immune-fluorescence picture is given below. Which of the following is incorrect about the condition shown?

Accepted Answer

Basement membrane deposition of IgG is the most common DIF picture in bullous lesions

Answer

Antibodies against hemidesmosomes

Answer

Antibodies against desmoglein 1

Answer

Antibodies against desmoglein-3

Question 3

A 42 year old man presented with recurrent oral ulcers since one year, episodes of redness of eye and genital ulcers. Which one of the following tests is of diagnostic value?

Accepted Answer

Pathergy test

Answer

Drug-sensitivity test

Answer

Patch test

Answer

Mantoux test

Question 4

Which one of the following is NOT true of Pyoderma gangrenosum?

Accepted Answer

Cultures often show Gram positive Staphylococci

Answer

It is often secondary to heightened immunological reactivity from another disease process

Answer

Lesions generally respond to steroids

Answer

It is characterized by cutaneous ulceration with purple undermined edges

Question 5

A 32-year-old woman presents with recurrent genital ulcers. She was previously diagnosed with genital herpes based on clinical appearance, but current PCR testing for HSV is negative. She also reports occasional painful mouth sores. Serological tests for syphilis are negative. What is the most likely diagnosis?

Accepted Answer

Behçet's syndrome

Answer

Fixed drug eruption

Answer

Crohn's disease

Answer

Aphthous ulcers

Question 6

A patient presents with skin lesions and erosions on the buccal mucosa. The immunofluorescence image is shown. What is the most likely diagnosis?

Accepted Answer

Pemphigus vulgaris

Answer

Bullous pemphigoid

Answer

Linear IgA disease

Answer

Dermatitis herpetiformis

Question 7

Identify the diagnosis based on the dermatology immunofluorescence (IF) image provided.

Accepted Answer

Dermatitis herpetiformis

Answer

Pemphigus vulgaris

Answer

Pemphigus foliaceus

Answer

Bullous pemphigoid

Question 8

A 30-year-old woman presents with flaccid bullae on her skin that are easy to rupture. A biopsy of the lesion reveals a suprabasal split. What is the most likely diagnosis?

Accepted Answer

Pemphigus vulgaris

Answer

Erythema multiforme

Answer

Pemphigus vegetans

Answer

Pemphigus foliaceous

Question 9

Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split.
Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.

Accepted Answer

Statements 1 & 2 are correct, 2 is not explaining 1

Answer

Statements 1 and 2 are correct and 2 is the correct explanation for 1

Answer

Statements 1 and 2 are incorrect

Answer

Statement 1 is incorrect

Question 10

A 25-year-old woman presents with multiple tense bullae on her arms and legs that developed over the past week. She reports taking amoxicillin for a sore throat 2 weeks ago. Skin biopsy shows subepidermal bulla formation with linear IgA deposits along the basement membrane. Which of the following is the most appropriate treatment?

Accepted Answer

Dapsone

Answer

Topical steroids

Answer

Oral antibiotics

Answer

Acyclovir

Autoimmune Skin Diseases — MCQs

Autoimmune Skin Diseases — MCQs

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