A lesion is seen on the same site on three different occasions. What is the most likely diagnosis?& x20; - INI-CET EXAM -2025

INI-CET EXAM -2025

Medical Surgical Nursing

Easy

Appeared in: INI-CET EXAM -2025

Explanation

A fixed drug eruption (FDE) is a delayed-type hypersensitivity reaction to a drug.
The hallmark of FDE is the recurrence of skin lesions at the exact same site upon re-exposure to the causative agent.
Lesions are typically solitary or few, well-demarcated, erythematous plaques that may become bullous.
Common causative drugs include NSAIDs, antibiotics (like sulfonamides and tetracyclines), and barbiturates.
After healing, the site often shows post-inflammatory hyperpigmentation.

Option A: Cutaneous mastocytosis involves a persistent accumulation of mast cells in the skin, leading to chronic lesions (like urticaria pigmentosa) rather than lesions that appear and disappear repeatedly in the same spot.
Option C: Herpes simplex virus (HSV) infections are known for recurrence, but the lesions typically reappear in the same general dermatomal area (e.g., perioral region), not the precise same spot every time.
Option D: Erythema multiforme is characterized by the acute onset of multiple, symmetrical, target-shaped lesions, often on the extremities. It does not present as a single lesion recurring at a fixed site.

Visual 1: Image - A classic fixed drug eruption lesion, showing a well-demarcated, dusky erythematous plaque on the skin. This helps visualize the typical appearance.
Visual 2: Diagram - A flowchart differentiating between FDE, HSV, and Erythema Multiforme based on lesion characteristics (location, recurrence pattern, morphology).

Clinical Relevance

Nursing practice connection: Use the key finding related to Differential diagnosis of recurrent skin lesions to guide bedside assessment, documentation, and the next nursing action.
A key nursing intervention is to take a detailed medication history, including over-the-counter drugs, when a patient presents with a suspected FDE. The timing between taking a drug and the lesion's appearance is crucial.
Patient education is vital. The patient must be informed about the specific drug causing the reaction and the importance of avoiding it in the future to prevent more severe reactions.
What if? - If the patient reported multiple, symmetrical target-like lesions on their hands and feet after a recent cold sore, the diagnosis would shift from FDE to Erythema Multiforme, as it is a common post-herpetic reaction.

How to Approach the Question

First, identify the key information in the question stem: a lesion that has appeared on the 'same site' on 'three different occasions'.
The phrase 'same site' is the most powerful diagnostic clue, indicating a fixed location.
Evaluate each option based on this key feature.
Recall or look up the definition of a Fixed Drug Eruption. Its defining characteristic is recurrence at the identical location upon re-exposure to a trigger.
Consider HSV-1. While recurrent, it affects a general region (dermatome), not the exact same spot.
Consider Erythema Multiforme. This involves multiple, symmetrical, target-like lesions, which is inconsistent with a single, recurring lesion.

Concept Tested & Keywords

Concept Tested: Differential diagnosis of recurrent skin lesions
Stem keywords: lesion, same site, three different occasions
Lead-in keywords: most likely diagnosis
Clinical cues: The recurrence of the lesion in the exact same spot is the most critical clue for diagnosis.

Qfrm7HPmslM3EDerbDcFNY