Question:medium
A 45 year old man presents with the following skin changes (image showing hyperpigmented, thickened rash over the neck and chest in a photosensitive distribution). What relevant history will you take to diagnose this condition?
A 45 year old man presents with the following skin changes (image showing hyperpigmented, thickened rash over the neck and chest in a photosensitive distribution). What relevant history will you take to diagnose this condition?
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Recall the three D's of Pellagra and which historical features you need to elicit to confirm the diagnosis.
Updated On: Jun 23, 2026
- H/o dietary pattern, dementia, diarrhea
- Dietary history
- Dementia
- Depression
Show Solution
The Correct Option is A
Solution and Explanation
Image interpretation: The skin changes shown -- hyperpigmented, rough, thickened rash over the neck and chest in a sun-exposed distribution (Casal's necklace) -- are pathognomonic of Pellagra.
Pellagra = Niacin (Vitamin B3) deficiency
To confirm the diagnosis of pellagra, the clinician must elicit history of all three classic features -- the 3 Ds:
Additionally, a dietary history focusing on maize/corn intake, alcohol use, or malabsorptive conditions explains the nutritional cause.
Option A -- H/o dietary pattern, dementia, diarrhea -- captures both the etiological (dietary) and clinical (dementia + diarrhea) history needed for diagnosis.
Options B, C, D are individually insufficient as they cover only one dimension of the syndrome.
\[\boxed{\text{H/o dietary pattern, dementia, diarrhea}}\]
Pellagra = Niacin (Vitamin B3) deficiency
To confirm the diagnosis of pellagra, the clinician must elicit history of all three classic features -- the 3 Ds:
- Dermatitis: Already evident on examination -- photosensitive, bilateral, symmetric
- Diarrhea: Ask about loose or watery stools
- Dementia: Ask about memory loss, confusion, or behavioral changes
Additionally, a dietary history focusing on maize/corn intake, alcohol use, or malabsorptive conditions explains the nutritional cause.
Option A -- H/o dietary pattern, dementia, diarrhea -- captures both the etiological (dietary) and clinical (dementia + diarrhea) history needed for diagnosis.
Options B, C, D are individually insufficient as they cover only one dimension of the syndrome.
\[\boxed{\text{H/o dietary pattern, dementia, diarrhea}}\]
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