Blistering Diseases Practice Questions

Q: Flaccid bullae with mucosal involvement and intraepidermal acantholysis are characteristic of which condition?

Pemphigus vulgaris. ***Pemphigus vulgaris*** - This autoimmune blistering disease is characterized by **flaccid bullae**, **mucosal involvement**, and **intraepidermal acantholysis**, specifically targeting **desmoglein 3** and often desmoglein 1. - The blistering occurs within the epidermis due to loss of cell-to-cell adhesion, leading to a positive **Nikolsky's sign**. *Pemphigus foliaceus* - This condition involves **superficial blistering** (subcorneal acantholysis) and typically presents with **crusted erosions** rather than intact flaccid bullae, often without mucosal involvement. - It primarily targets **desmoglein 1**, leading to blistering in the more superficial layers of the epidermis. *Psoriasis* - This is a chronic inflammatory skin condition characterized by **erythematous plaques** with silvery scales, often on extensor surfaces. - It involves **epidermal hyperplasia** and inflammation, not blistering due to acantholysis. *Vitiligo* - Vitiligo is a **pigmentary disorder** characterized by **depigmented patches** of skin caused by the destruction of melanocytes. - It does not involve bullae, acantholysis, or any form of blistering.

Q: Which type of collagen is mutated in dystrophic epidermolysis bullosa?

Type VII. ***Type VII*** - **Type VII collagen** forms **anchoring fibrils** that connect the epidermis to the dermis at the dermal-epidermal junction, providing essential skin integrity. - Mutations in the gene encoding type VII collagen (**COL7A1**) lead to **dystrophic epidermolysis bullosa (DEB)**, characterized by severe blistering and skin fragility due to poor dermal-epidermal adhesion. - Note: Other forms of epidermolysis bullosa involve different proteins (e.g., keratins in EB simplex, laminin-332 in junctional EB). *Type I* - **Type I collagen** is the most abundant collagen in the body, found in **skin, bone, tendons, and ligaments**. - Mutations in type I collagen are primarily associated with conditions like **osteogenesis imperfecta**, causing brittle bones, not epidermolysis bullosa. *Type II* - **Type II collagen** is predominantly found in **cartilage**, making up the structural framework of hyaline cartilage. - Mutations in type II collagen are linked to **chondrodysplasias** and other skeletal disorders affecting cartilage development, not skin blistering. *Type IV* - **Type IV collagen** is a major component of **basement membranes**, providing structural support and filtration in various tissues. - Mutations in type IV collagen are associated with conditions like **Alport syndrome** (kidney/ear disease), not dystrophic epidermolysis bullosa.

Q: Which of the following statements is true regarding pemphigus vulgaris?

It is an intraepidermal blistering disease.. ***It is an intraepidermal blistering disease.*** - **Pemphigus vulgaris** is characterized by the formation of blisters *within the epidermis* due to the loss of cell-to-cell adhesion between **keratinocytes**. - This **acantholysis** results from autoantibodies targeting **desmosomes**, specifically **desmoglein 1 and 3**. *It is a subepidermal blistering disease.* - This statement is incorrect as it describes conditions like **bullous pemphigoid** or **dermatitis herpetiformis**, where blisters form *below* the epidermis. - In pemphigus vulgaris, the separation occurs *above* the basement membrane within the epidermal layer. *It primarily affects the dermal-epidermal junction.* - This is characteristic of **bullous pemphigoid** or **epidermolysis bullosa acquisita**, where the primary pathology involves the separation at the interface between the dermis and epidermis. - Pemphigus vulgaris directly affects the adhesion *within* the epidermis itself. *Antibodies are formed against basement membrane proteins.* - This is characteristic of **bullous pemphigoid**, where autoantibodies target components of the **basement membrane zone**, such as **BP180** and **BP230**. - In pemphigus vulgaris, the autoantibodies target **desmogleins** on the surface of keratinocytes, not basement membrane proteins.

Q: Pruritus is a feature of which of the following conditions?

Bullous pemphigoid. ***Bullous pemphigoid*** - **Pruritus**, often severe, is a common and early symptom of bullous pemphigoid, often preceding the appearance of skin lesions. - The disease involves autoantibodies against **hemidesmosomal proteins** (BPAG1, BPAG2), leading to subepidermal blister formation. *Pemphigus foliaceous* - This condition is characterized by **superficial blistering** and erosions, but **pruritus is typically mild or absent**. - Blisters form in the **granular layer of the epidermis** due to autoantibodies against desmoglein 1. *Pemphigus vulgaris* - Patients with pemphigus vulgaris present with **flaccid blisters and erosions**, mainly affecting the skin and mucous membranes, but **pruritus is not a prominent feature**. - The disease involves intraepidermal blistering caused by autoantibodies targeting **desmoglein 3 (and sometimes desmoglein 1)**. *None of the options* - This option is incorrect, as **pruritus is a characteristic symptom of bullous pemphigoid**.

Q: A 40 year old male reported with recurrent episodes of oral ulcers, large areas of denuded skin and flaccid vesiculo-bullous eruptions. Which is the most important bedside investigation helpful in establishing the diagnosis -

Tzanck smear from the floor of bulla. ***Tzanck smear from the floor of bulla*** - A Tzanck smear from the floor of a bulla will reveal **acantholytic cells** (rounded keratinocytes that have lost their intercellular connections), which are characteristic of pemphigus, consistent with recurrent oral ulcers, denuded skin, and flaccid vesiculobullous eruptions. - This **bedside test** provides a rapid diagnosis by demonstrating the cytological features of acantholysis, differentiating it from other blistering disorders. *Gram staining of blister fluid* - This test is primarily used to identify **bacterial infections** and would show the morphology and Gram-staining characteristics of any bacteria present. - It would not provide information about the **acantholysis** or autoimmune nature of the blistering condition described. *Culture and sensitivity of blister fluid* - This investigation identifies **specific bacterial pathogens** and their antibiotic susceptibilities, which is useful for treating bacterial infections. - It would not help in diagnosing **autoimmune blistering diseases** like pemphigus, where bacteria are not the primary cause of the lesions. *Skin biopsy with immunofluorescence* - While a **skin biopsy with direct immunofluorescence** is the gold standard for confirming pemphigus by detecting autoantibodies, it is an **invasive procedure** requiring laboratory processing and is not considered a rapid bedside investigation. - The question specifically asks for the "most important **bed-side investigation**" helpful in establishing the diagnosis rapidly.

Q: Nikolsky's sign is associated with which of the following conditions?

Pemphigus. ***Pemphigus*** - **Nikolsky's sign** is the **most characteristic and consistent** clinical finding in pemphigus, where slight lateral pressure on seemingly normal skin near a blister or erosion causes the epidermis to shear off, forming a new blister or denudation. - This sign indicates **intraepidermal blistering** due to the loss of cell adhesion (acantholysis) caused by autoantibodies against desmoglein proteins. - **Pemphigus is the classic condition** associated with a positive Nikolsky's sign in medical literature and examinations. *Herpes zoster* - **Herpes zoster** (shingles) is characterized by painful, vesicular eruptions in a **dermatomal distribution**, which do **not exhibit Nikolsky's sign**. - The vesicles in herpes zoster are **intraepidermal** but result from viral cytopathic effect, not acantholysis, and the roof of the vesicle remains intact with lateral pressure. *Bullous impetigo* - Bullous impetigo is a superficial skin infection caused by *Staphylococcus aureus* that produces **large, flaccid blisters**. - While **Nikolsky's sign can occasionally be positive** in bullous impetigo (particularly in staphylococcal scalded skin syndrome), it is **much less consistent and prominent** compared to pemphigus. - The key distinction is that pemphigus remains the **most characteristic association** with Nikolsky's sign in clinical practice and examinations. *All of the options* - This option is incorrect because Nikolsky's sign is **most specifically and consistently associated with pemphigus**. - While bullous impetigo may occasionally show Nikolsky's sign, **pemphigus is the classic answer** for this clinical finding in medical examinations.

Q: Which of the following drug classes is commonly implicated in causing Stevens-Johnson syndrome?

Antibiotics. ***Antibiotics*** - **Antibiotics**, particularly **sulfonamides** (e.g., sulfamethoxazole-trimethoprim) and **beta-lactams** (e.g., penicillins, cephalosporins), are among the most common drug classes implicated in causing **Stevens-Johnson Syndrome (SJS)**. - SJS is a severe **idiosyncratic drug reaction**, and many antibiotics can trigger this immune-mediated response. - **Note:** Other major causative drug classes include **anticonvulsants** (carbamazepine, phenytoin, lamotrigine), **allopurinol**, and **NSAIDs**, but among the options listed, antibiotics are the most commonly implicated. *Corticosteroids* - **Corticosteroids** are typically used in the **treatment** of SJS to suppress the immune response and reduce inflammation, not to cause it. - While they have their own set of side effects, initiating SJS is not one of their known adverse reactions. *Antifungals* - Although some **antifungals** can cause adverse drug reactions, they are **not typically associated** with SJS compared to antibiotics, anticonvulsants, or allopurinol. - The risk of SJS with antifungal medications is generally very low. *Proton pump inhibitors* - **Proton pump inhibitors (PPIs)** are generally well-tolerated and are **rarely implicated** as a cause of SJS. - Their primary side effects are usually gastrointestinal and not severe dermatological reactions.

Q: A 26-year-old girl at 31 weeks' gestation complains of a 4-week history of a pustular eruption that initially developed on the periumbilical skin and subsequently spread to involve the breasts, back, flexures, and proximal limbs, accompanied by cutaneous pain, fever, and malaise. On examination, the lesions were found to be pustules arranged in concentric rings, while on the breasts, there was coalescence of pustules forming lakes of pus. What is the treatment of choice in this case?

Corticosteroids. ***Corticosteroids*** - The constellation of **pustular eruption** with **concentric rings**, especially in pregnancy, along with systemic symptoms like fever and malaise, is highly suggestive of **Pustular Psoriasis of Pregnancy (PPP)**, also known as **Impetigo Herpetiformis**. - **Systemic corticosteroids** (prednisolone) are the **first-line treatment** for this rare but severe dermatosis in pregnancy, aimed at controlling inflammation and preventing maternal and fetal complications. *Methotrexate* - **Methotrexate** is an **anti-metabolite** and **immunosuppressant** that is **teratogenic** and absolutely **contraindicated in pregnancy** due to its potential to cause severe birth defects and miscarriages. - While it can be used for severe psoriasis in non-pregnant individuals, its use in this pregnant patient is inappropriate and dangerous. *Topical itraconazole* - **Itraconazole** is an **antifungal medication** used to treat fungal infections. While typically used systemically, topical formulations exist for localized fungal infections. - The clinical presentation of widespread pustules arranged in **concentric rings** with systemic symptoms and **"lakes of pus"** in a pregnant woman is pathognomonic for **Impetigo Herpetiformis**, not a fungal infection, making this treatment inappropriate. *Third generation cephalosporins* - **Third-generation cephalosporins** are **antibiotics** primarily used to treat bacterial infections. - The distinctive pattern of **pustules in concentric rings**, the periumbilical onset, and progression to form **lakes of pus** in a pregnant woman represents an **inflammatory dermatosis** (Impetigo Herpetiformis), not a primary bacterial infection requiring antibiotics.

Q: All of the following diseases cause intraepidermal bullae except:

Herpes gestationalis. ***Herpes gestationalis.*** - Herpes gestationalis is characterized by **urticarial papules** and vesicles, typically occurs in pregnancy, and does not form **intraepidermal bullae**. - This condition is linked more with **dermatitis herpetiformis** rather than with the intraepidermal blistering seen in the other options [2]. *Herpes zoster* - Herpes zoster causes **vesicular lesions** that are often grouped, presenting as painful **erythematous vesicles** along a dermatome. - The lesions can form intraepidermal bullae due to the **varicella-zoster virus** affecting the skin [1]. *Miliaria rubra* - Miliaria rubra, or **heat rash**, results from occluded sweat glands leading to **superficial vesicles or papules** in the epidermis. - The lesions may resemble blisters but are not true intraepidermal bullae and are prominent in hot, humid conditions. *Pemphigus* - Pemphigus is an autoimmune disorder causing **flaccid bullae** due to **acantholysis** in the epidermis, leading to intraepidermal bulla formation [3]. - It is characterized by **painful, fragile blisters** that rupture easily, differentiating it from other conditions listed [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 366. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1172-1174. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1170-1172.

Question 1

Flaccid bullae with mucosal involvement and intraepidermal acantholysis are characteristic of which condition?

Accepted Answer

Pemphigus vulgaris

Answer

Pemphigus foliaceus

Answer

Psoriasis

Answer

Vitiligo

Question 2

Which type of collagen is mutated in dystrophic epidermolysis bullosa?

Accepted Answer

Type VII

Answer

Type I

Answer

Type II

Answer

Type IV

Question 3

Which of the following statements is true regarding pemphigus vulgaris?

Accepted Answer

It is an intraepidermal blistering disease.

Answer

It primarily affects the dermal-epidermal junction.

Answer

It is a subepidermal blistering disease.

Answer

Antibodies are formed against basement membrane proteins.

Question 4

Pruritus is a feature of which of the following conditions?

Accepted Answer

Bullous pemphigoid

Answer

Pemphigus foliaceous

Answer

Pemphigus vulgaris

Answer

None of the options

Question 5

A 40 year old male reported with recurrent episodes of oral ulcers, large areas of denuded skin and flaccid vesiculo-bullous eruptions. Which is the most important bedside investigation helpful in establishing the diagnosis -

Accepted Answer

Tzanck smear from the floor of bulla

Answer

Gram staining of blister fluid

Answer

Culture and sensitivity of blister fluid

Answer

Skin biopsy with immunofluorescence

Question 6

Acantholysis is not seen in:

Accepted Answer

Lichen planus

Answer

Dermatitis herpetiformis

Answer

Hailey-Hailey disease

Answer

Bullous pemphigoid

Question 7

Nikolsky's sign is associated with which of the following conditions?

Accepted Answer

Pemphigus

Answer

Herpes zoster

Answer

Bullous impetigo

Answer

All of the options

Question 8

Which of the following drug classes is commonly implicated in causing Stevens-Johnson syndrome?

Accepted Answer

Antibiotics

Answer

Corticosteroids

Answer

Antifungals

Answer

Proton pump inhibitors

Question 9

A 26-year-old girl at 31 weeks' gestation complains of a 4-week history of a pustular eruption that initially developed on the periumbilical skin and subsequently spread to involve the breasts, back, flexures, and proximal limbs, accompanied by cutaneous pain, fever, and malaise. On examination, the lesions were found to be pustules arranged in concentric rings, while on the breasts, there was coalescence of pustules forming lakes of pus. What is the treatment of choice in this case?

Accepted Answer

Corticosteroids

Answer

Methotrexate

Answer

Topical itraconazole

Answer

Third generation cephalosporins

Question 10

All of the following diseases cause intraepidermal bullae except:

Accepted Answer

Herpes gestationalis

Answer

Miliaria rubra

Answer

Herpes zoster

Answer

Pemphigus

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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