FMGE 2025 - Dermatology Practice Questions

Q: A patient with borderline tuberculoid leprosy presents with the following findings. Which type of hypersensitivity reaction and nerve is enlarged?

Type 4 & greater auricular nerve. ***Type 4 & greater auricular nerve*** - Borderline tuberculoid leprosy is characterized by a strong **cell-mediated immune response** against *Mycobacterium leprae*, which manifests as a **Type 4 (delayed-type) hypersensitivity** reaction leading to granuloma formation. - The image shows a thickened, cord-like structure in the neck, which is characteristic of an enlarged **greater auricular nerve**, the most commonly involved cutaneous nerve of the head and neck in leprosy. *Type 1 & greater auricular nerve* - **Type 1 hypersensitivity** is an immediate, **IgE-mediated** reaction (e.g., anaphylaxis) and is not the immunological basis for nerve damage or skin lesions in tuberculoid leprosy. - The pathogenesis of tuberculoid leprosy involves a **delayed-type** T-cell response, which takes days to develop, unlike the rapid onset of Type 1 reactions. *Type 2 & greater auricular nerve* - **Type 2 hypersensitivity** is an **antibody-dependent cytotoxic** reaction, which is not the primary mechanism in tuberculoid leprosy's pathology. - While immune reactions occur in leprosy, Type 2 is not the correct classification for the T-cell-mediated granulomatous inflammation seen in the tuberculoid form. *Type 3 & anterior auricular nerve* - **Type 3 hypersensitivity** involves **immune-complex deposition** and is characteristic of **Erythema Nodosum Leprosum (ENL)**, a complication typically seen in lepromatous leprosy, not borderline tuberculoid. - The enlarged nerve shown is clearly the **greater auricular nerve** due to its location crossing the sternocleidomastoid muscle; the **anterior auricular nerve** is located more anteriorly and is not typically affected this prominently.

Q: A patient presents to the dermatology clinic reporting recurrent skin lesions as seen on the image. He describes that these lesions emerge within hours each time he takes NSAIDs. What is the most likely diagnosis?

Fixed drug eruptions. ***Fixed drug eruptions*** - This is the classic presentation of a fixed drug eruption (FDE), characterized by the recurrent appearance of one or more well-demarcated, erythematous to violaceous patches or plaques in the **exact same location** each time the causative drug (in this case, **NSAIDs**) is administered. - The lesions typically appear within hours of drug exposure and resolve over days to weeks, often leaving behind a slate-gray or brown **post-inflammatory hyperpigmentation**. *Erythema multiforme* - This condition is characterized by distinctive **targetoid lesions** (iris lesions), which have at least three concentric zones of color change. The lesion in the image is a uniform plaque, not a target lesion. - While drugs can be a cause, erythema multiforme is most commonly triggered by infections, particularly the **Herpes Simplex Virus (HSV)**. *Drug Induced Pigmentation* - This refers to a discoloration of the skin caused by drugs, but it typically lacks the acute inflammatory features (erythema, edema) seen in an FDE. It is a more chronic and insidious process. - It is commonly associated with drugs like **minocycline**, **amiodarone**, or antimalarials and presents as diffuse or patterned hyperpigmentation, not as a recurrent inflammatory plaque. *Herpes* - Herpes virus infections classically present as grouped **vesicles** (small blisters) on an erythematous base, which then evolve into pustules and crusted erosions. The image shows a plaque, not vesicles. - Recurrence is common with herpes, but it is not triggered by medication ingestion; rather, it's often precipitated by stress, illness, or immunosuppression.

Question 1

A patient with borderline tuberculoid leprosy presents with the following findings. Which type of hypersensitivity reaction and nerve is enlarged?

Accepted Answer

Type 4 & greater auricular nerve

Answer

Type 1 & greater auricular nerve

Answer

Type 3 & anterior auricular nerve

Answer

Type 2 & greater auricular nerve

Question 2

A patient presents to the dermatology clinic reporting recurrent skin lesions as seen on the image. He describes that these lesions emerge within hours each time he takes NSAIDs. What is the most likely diagnosis?

Accepted Answer

Fixed drug eruptions

Answer

Erythema multiforme

Answer

Herpes

Answer

Drug Induced Pigmentation

FMGE 2025 — Dermatology