Dermatological Pharmacology — MCQs

Dermatological Pharmacology Indian Medical PG Practice Questions and MCQs

Question 61: The patient came with history of bullae involving >30% of body surface area along with erosions of the lips and other mucosae for the past 7 days. What is the most probable underlying etiology?

A. Bacterial skin infection
B. Viral skin infection
C. Drug reaction (Correct Answer)
D. Skin malignancy

Explanation: ***Drug reaction*** - The formation of widespread bullae involving >30% of the body surface area, along with significant mucosal erosions (lips), points strongly towards **toxic epidermal necrolysis (TEN)**, a severe form of cutaneous adverse drug reaction. - TEN is characterized by **extensive epidermal detachment** resulting from a drug-induced immune response, commonly occurring within days to weeks of drug exposure. *Bacterial skin infection* - While certain bacterial infections can cause bullae (e.g., **bullous impetigo**), they rarely lead to such widespread involvement (>30% BSA) and extensive mucosal erosions within 7 days, as seen in TEN. - The rapid progression to severe, widespread blistering and mucosal involvement is more typical of drug-induced hypersensitivity rather than common bacterial skin infections. *Viral skin infection* - Viral infections like **herpes simplex virus** or **varicella-zoster virus** can cause bullae, but typically in localized patterns or with specific morphologies (e.g., vesicles on an erythematous base) and usually without such extensive body surface area involvement or severe mucosal erosion in an immunocompetent adult. - Widespread bullae and mucosal erosions over >30% BSA are not characteristic of typical viral skin infections. *Skin malignancy* - Skin malignancies, such as **cutaneous lymphomas** or other aggressive tumors, can present with various skin lesions, but they rarely manifest acutely with widespread bullae and erosions involving >30% of the body surface area within a 7-day timeframe. - Such a rapid and severe presentation is inconsistent with the typical indolent or slowly progressive nature of most primary skin cancers.

Question 62: A 27-year-old sexually active male develops a vesiculobullous lesion on the glans shortly after taking a tablet of paracetamol for fever. The lesion healed with hyperpigmentation. What is the most likely diagnosis?

A. Behcet's syndrome
B. Herpes genitalis
C. Fixed drug eruption (Correct Answer)
D. Pemphigus vulgaris

Explanation: ***Fixed drug eruption*** - A **fixed drug eruption** is highly suggested by the development of a solitary **vesiculobullous lesion** on the glans shortly after taking **paracetamol**, which then heals with **hyperpigmentation**. The recurrence at the same site upon re-exposure to the drug is a hallmark. - The rapid appearance following drug intake and the consistent site of eruption with residual pigmentation are classic features. *Behcet's syndrome* - Behcet's syndrome is a **multisystemic inflammatory disorder** characterized by recurrent **oral** and **genital ulcers**, skin lesions, and ocular inflammation. - While it involves genital ulcers, its recurrent nature, systemic symptoms (like uveitis or neurological manifestations), and lack of a clear drug trigger differentiate it from this presentation. *Herpes genitalis* - Herpes genitalis presents with clusters of small, painful, itching **vesicles** often on an erythematous base, but it is caused by the **herpes simplex virus (HSV)** and is sexually transmitted, not drug-induced. - Lesions from herpes typically recur due to viral reactivation, but not in response to a specific medication, and typically resolve without significant hyperpigmentation unless secondary infection occurs. *Pemphigus vulgaris* - Pemphigus vulgaris is a rare, severe **autoimmune blistering disease** affecting the skin and mucous membranes, characterized by **flaccid bullae** that rupture easily, leading to erosions. - This condition presents with widespread blistering, not a solitary, drug-induced lesion, and typically does not heal with localized hyperpigmentation in this manner.

Practice by Chapter

Topical Corticosteroids

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Topical Antibiotics

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Topical Antifungals

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Topical Antivirals

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Topical Retinoids

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Systemic Retinoids

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Immunosuppressive Agents

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Antihistamines in Dermatology

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Biological Agents in Dermatology

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Dermatological Vehicles and Delivery Systems

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Phototherapeutic Agents

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Adverse Cutaneous Drug Reactions

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