Blistering Diseases Practice Questions

Q: A patient presents with a history of bullae involving more than 30% of the body surface area, along with rashes all over the body and erosions of the lips and other mucosa, for a few days. What could be the potential triggering factor for this condition?

Drug induced. ***Correct: Drug induced*** - The severe presentation with widespread **bullae** covering over 30% of the body surface area, extensive rashes, and **mucosal erosions** (lips) is highly suggestive of **Toxic Epidermal Necrolysis (TEN)**. - TEN is most commonly **drug-induced**, often triggered by medications like **antibiotics** (sulfonamides, penicillins), **anticonvulsants** (carbamazepine, phenytoin, lamotrigine), **NSAIDs**, and **allopurinol**. - The combination of extensive skin detachment (>30% BSA), mucosal involvement, and acute onset strongly points to a drug-induced etiology. *Incorrect: Viral infection* - While some viral infections can cause rashes and mucocutaneous lesions, they typically do not lead to such widespread **epidermal detachment** and severe **mucosal erosions** affecting over 30% BSA, as seen in TEN. - Viral exanthems (e.g., measles, herpes) are generally milder and have different morphology compared to the full-thickness epidermal necrosis seen in this condition. *Incorrect: Bacterial infection* - Bacterial skin infections can cause **bullous impetigo** or **staphylococcal scalded skin syndrome (SSSS)**, but SSSS typically spares the mucous membranes and involves superficial epidermal splitting (not full-thickness necrosis). - The extent and severity of the lesions, including widespread **mucosal involvement**, are more consistent with a systemic hypersensitivity reaction rather than a localized or superficial bacterial infection. *Incorrect: Idiopathic* - Although the cause can sometimes be undetermined, the pattern of severe symptoms described—especially with extensive **skin sloughing** and **mucosal involvement**—points strongly to a known etiology. - TEN has a well-established association with drug triggers in **80-95% of cases**, making a truly idiopathic cause unlikely in the absence of thorough drug history evaluation.

Q: Nikolsky's sign is seen in all of the following, except:

Bullous pemphigoid. ***Bullous pemphigoid*** - **Nikolsky's sign** is typically **negative** in bullous pemphigoid because the blistering occurs in the **subepidermal region**, leading to a strong dermo-epidermal adhesion that resists tangential pressure. - The blisters in bullous pemphigoid are generally **tense** and do not rupture easily, reflecting the deep separation plane. *Mucous membrane pemphigoid* - **Nikolsky's sign** is typically **negative** in mucous membrane pemphigoid (also known as cicatricial pemphigoid) because it is also a **subepidermal blistering disorder**. - Like bullous pemphigoid, the cleavage occurs below the epidermis, preserving the integrity of the epidermal layer and maintaining resistance to lateral shearing forces. - The blisters are typically tense rather than flaccid, reflecting the deeper plane of separation. *Toxic epidermal necrolysis* - **Nikolsky's sign** is **positive** in toxic epidermal necrolysis (TEN) due to the extensive **full-thickness epidermal necrosis** and detachment, which is the hallmark of the condition. - Gentle tangential pressure causes the epidermis to easily shear off, revealing large areas of denuded dermis. *Scalded skin syndrome* - **Nikolsky's sign** is **positive** in scalded skin syndrome (SSSS) because the **exfoliative toxins** produced by *Staphylococcus aureus* cleave **desmoglein 1** in the superficial epidermis. - This cleavage leads to rapid and widespread **intraepidermal detachment** and flaccid blistering, making the skin highly susceptible to shearing.

Q: All are true about erythema multiforme except which of the following?

Does not involve mucosa. ***Does not involve mucosa*** - Erythema multiforme often presents with **mucosal involvement**, particularly in the oral cavity, which can range from mild erosions to severe blistering. - The presence of mucosal lesions, especially oral, ocular, or genital, is a key feature distinguishing more severe forms like **erythema multiforme major**. *Target lesion* - The **target lesion** (or iris lesion) is the hallmark dermatological finding in erythema multiforme, characterized by concentric rings of different colors. - This classic lesion is crucial for the clinical diagnosis of erythema multiforme. *Associated with HSV* - **Herpes Simplex Virus (HSV) infection** is the most common precipitating factor for erythema multiforme, especially for recurrent episodes. - The onset of lesions typically follows an HSV outbreak by several days to weeks. *Extensor involvement* - The rash of erythema multiforme commonly affects the **extensor surfaces of the extremities**, such as the dorsal hands, forearms, and shins. - While it can appear elsewhere, this distribution is a characteristic pattern.

Q: In an 8-day-old child with no history of consanguinity in the parents, the mother reports blisters and bleeding off the skin at the site of handling and pressure. There was a similar history in the previous child, which proved to be fatal. The diagnosis is

Epidermolysis bullosa. ***Epidermolysis bullosa*** - The presentation of **blisters and bleeding** at sites of trauma and handling in a neonate is pathognomonic for **epidermolysis bullosa (EB)**. - EB is a group of **inherited mechanobullous disorders** characterized by skin fragility; severe forms like **EB letalis (Herlitz type)** are **autosomal recessive** and often fatal in infancy. - The **positive family history** (previous fatal sibling) strongly suggests an inherited genetic disorder, consistent with EB. - The blisters occur at sites of **mechanical stress**, exactly as described in this case. *Bullous pemphigoid* - This is an **autoimmune blistering disease** typically affecting **older adults (>60 years)**, not neonates. - It is **not inherited** and does not present with a familial pattern. - Blisters are usually **tense and widespread**, not specifically triggered by handling or pressure. *Congenital syphilis* - Can cause **pemphigus syphiliticus** (bullous lesions on palms and soles) in the first few weeks of life. - However, it is an **infectious disease**, not inherited, so the **fatal outcome in a previous sibling** would not follow this pattern unless both were infected in utero. - Typically associated with other findings: **hepatosplenomegaly**, **rhinitis (snuffles)**, **skeletal abnormalities**, and positive maternal/infant serology. - Would be preventable with maternal screening and treatment. *Letterer-Siwe disease (Langerhans cell histiocytosis)* - Presents with **seborrheic-like or petechial rash**, hepatosplenomegaly, and systemic involvement. - Skin lesions are typically **papular, crusted, or purpuric**, not mechanically-induced blisters. - Does not characteristically present with **trauma-induced blistering** as the primary feature.

Q: Acantholysis is seen in which of the following conditions?

Pemphigus vulgaris. ***Pemphigus vulgaris*** - **Pemphigus vulgaris** is the **prototypical example** of acantholysis, characterized by **autoantibodies** against **desmoglein 1 and 3**, components of **desmosomes**, leading to the loss of cell-cell adhesion or **acantholysis** within the epidermis. - This **acantholysis** results in the formation of **intraepidermal blisters** that are typically flaccid and rupture easily, leading to erosions. - Histologically shows **tombstone pattern** with complete loss of intercellular adhesion throughout the epidermis. *Darier's disease* - **Darier's disease** is an autosomal dominant disorder due to mutations in the **ATP2A2 gene**. - While it does show **focal acantholytic dyskeratosis** histologically, the primary feature is **dyskeratosis** (premature/abnormal keratinization) with characteristic **corps ronds** and **grains**. - The acantholysis is **focal and suprabasal**, associated with dyskeratotic cells, unlike the widespread acantholysis of pemphigus. *Staphylococcal scalded skin syndrome* - This condition is caused by **exfoliative toxins** (ETA, ETB) produced by *Staphylococcus aureus*, which target **desmoglein 1** in the **superficial epidermis**. - While it does cause **acantholysis in the granular layer**, this is **toxin-mediated** rather than autoimmune. - The split occurs in the **superficial granular layer only**, with intact deeper epidermis, unlike the mid-epidermal split in pemphigus vulgaris. *Bullous pemphigoid* - **Bullous pemphigoid** is an autoimmune blistering disease where antibodies target components of the **hemidesmosomes** in the **basement membrane zone**, specifically BP180 and BP230. - This leads to a **subepidermal split**, meaning the epidermis separates from the dermis as an intact layer. - There is **no acantholysis** - the keratinocytes remain adherent to each other; the separation occurs at the dermal-epidermal junction.

Question 1

A patient presents with a history of bullae involving more than 30% of the body surface area, along with rashes all over the body and erosions of the lips and other mucosa, for a few days. What could be the potential triggering factor for this condition?

Accepted Answer

Drug induced

Answer

Viral infection

Answer

Bacterial infection

Answer

Idiopathic

Question 2

Nikolsky's sign is seen in all of the following, except:

Accepted Answer

Bullous pemphigoid

Answer

Toxic epidermal necrolysis

Answer

Scalded skin syndrome

Answer

Mucous membrane pemphigoid

Question 3

All are true about erythema multiforme except which of the following?

Accepted Answer

Does not involve mucosa

Answer

Associated with HSV

Answer

Target lesion

Answer

Extensor involvement

Question 4

In an 8-day-old child with no history of consanguinity in the parents, the mother reports blisters and bleeding off the skin at the site of handling and pressure. There was a similar history in the previous child, which proved to be fatal. The diagnosis is

Accepted Answer

Epidermolysis bullosa

Answer

Bullous pemphigoid

Answer

Congenital syphilis

Answer

Letterer-Siwe disease (Langerhans cell histiocytosis)

Question 5

Acantholysis is seen in which of the following conditions?

Accepted Answer

Pemphigus vulgaris

Answer

Darier's disease

Answer

Staphylococcal scalded skin syndrome

Answer

Bullous pemphigoid

Blistering Diseases — MCQs

Blistering Diseases — MCQs

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