Nutrition and the skin — Viva

Q1: Definition and cutaneous prototypes (2 min)

How do you organise nutritional skin disease at the bedside?

Model answer. Pattern first, nutrient second. Follicular: phrynoderma (Monshi, low vitamin A after bariatric lactation) and scurvy corkscrew hairs (El Khoury). Periorificial-acral: acrodermatitis enteropathica (Ogawa: ZIP4). Photodistributed: pellagra Casal dermatitis and the 4 Ds (Mousa). Mucocutaneous: riboflavin cheilosis, angular stomatitis, glossitis (McNulty); B12 dorsal-hand and palmar hyperpigmentation (Mathur); scurvy gingival bleeding (Cui/El Khoury). Protein-energy: kwashiorkor flaky-paint dermatosis and hair flag sign (Mann). ^{[8][36][5][19][10][13][22]}

Q2: Differentials that trap candidates (3 min)

Name three misdiagnoses and the discriminator.

Model answer. Kwashiorkor versus atopic dermatitis — oedema, dietary restriction, flaky-paint change (Xavier/Mann). Scurvy versus ordinary follicular rash — corkscrew hairs on biopsy and a fruit-and-vegetable-free diet, including in non-cachectic dialysis patients (El Khoury). Pellagra versus other photodermatoses — clinical 4 Ds; tests are secondary and delay is common because the disease is unfamiliar (Hołubiec, taught from the pellagra refs). Post-bariatric lactation can mix phrynoderma and acquired AE (Monshi). ^{[22][36][19][8][20]}

Q3: Investigations (2 min)

What would you send, and what must you not over-interpret?

Model answer. Match the pattern: zinc (and a therapeutic trial if the assay is unavailable), vitamin C context, B12 if hyperpigmentation, niacin clinically rather than as a single lab, ATP7A pathway if a male neonate is in the first 4 to 6 weeks with suspected Menkes (Kaler). Zinc and related proteins behave as acute-phase reactants. B-vitamin pathways overlap, so one abnormal mucocutaneous sign is not a single-nutrient diagnosis. ^{[5][13][15][10]}

Q4: Management (3 min)

Give only regimens that appear in the cited abstracts.

Model answer. Pellagra: niacinamide; a published case used niacin 500 mg once daily until lesions resolved. AE-pattern zinc deficiency: oral zinc sulfate 220 mg 3 times a day produced rapid resolution in Changela; premature TPN infants may need more than 400 microg/kg/day. Scurvy: ascorbic acid 500 mg twice daily for 2 weeks resolved corkscrew-hair scurvy in El Khoury. SAM: WHO F-75 then F-100 (Rashid). Genetic AE needs ongoing zinc. Do not recite unsourced NICE/Pabrinex milligram protocols. ^{[19][29][30][36][25]}

Q5: Complications and prognosis (2 min)

What kills or blinds the candidate who delays?

Model answer. Untreated pellagra leads to death. SAM death risk is 9 times that of well-nourished children; hospitalised SAM death has been as high as 15 percent. Scurvy impairs collagen, causing bleeding and delayed wound healing; it has re-emerged in food-insecure populations. Menkes treatment opportunity is the first 4 to 6 weeks of life. Selenium deficiency is an aetiological risk factor for Keshan disease. ^{[19][25][1][15][14]}

References14ShowHide

1. [14]Hao S, Li G, Wang R, et al. Linear and nonlinear modeling of selenium biomarker dynamics in Keshan disease: Insights for precision prevention from rats and human populations Ecotoxicol Environ Saf, 2026.PMID 42296709
2. [20]Hołubiec P, Leończyk M, Staszewski F, et al. Pathophysiology and clinical management of pellagra - a review Folia Med Cracov, 2021.PMID 34882669
3. [29]Changela A, Javaiya H, Changela K, et al. Acrodermatitis enteropathica during adequate enteral nutrition JPEN J Parenter Enteral Nutr, 2012.PMID 22038206
4. [30]Barbarot S, Chantier E, Kuster A, et al. Symptomatic acquired zinc deficiency in at-risk premature infants: high dose preventive supplementation is necessary Pediatr Dermatol, 2010.PMID 20653858
5. [1]Pullar JM, Carr AC, Vissers MCM. The Roles of Vitamin C in Skin Health Nutrients, 2017.PMID 28805671
6. [5]Ogawa Y, Kinoshita M, Shimada S, et al. Zinc and Skin Disorders Nutrients, 2018.PMID 29439479
7. [8]Monshi B, Stockinger T, Vigl K, et al. Phrynoderma and acquired acrodermatitis enteropathica in breastfeeding women after bariatric surgery J Dtsch Dermatol Ges, 2015.PMID 26513075
8. [10]McNulty H, Pentieva K, Ward M. Causes and Clinical Sequelae of Riboflavin Deficiency Annu Rev Nutr, 2023.PMID 37603429
9. [13]Mathur M, Paudel S, Karki S, et al. Skin Hyperpigmentation: An Under-Recognized Dermatological Clue to Vitamin B12 Deficiency Clin Case Rep, 2026.PMID 42052311
10. [15]Kaler SG, Venkataraman L, Pham MT, et al. Whole genome sequencing from dried blood spots for newborn screening of Menkes disease and 36 other actionable inherited neurometabolic disorders Mol Genet Metab, 2026.PMID 41687279
11. [19]Mousa TY, Mousa OY. Nicotinic Acid Deficiency StatPearls, 2026.PMID 32491681
12. [22]Mann D, Presotto C, Queen SM, et al. Cutaneous manifestations of kwashiorkor: a case report of an adult man after abdominal surgery An Bras Dermatol, 2011.PMID 22281907
13. [25]Rashid MA, Rahman ME, Kamruzzaman M, et al. Efficacy of F-75 & F-100 Recipes in theTreatment of Severe Acute Malnutrition: A Randomized Controlled Trial Mymensingh Med J, 2019.PMID 31599256
14. [36]El Khoury R, Warren M, Ali S, et al. An Unexpected Case of Scurvy in a Peritoneal Dialysis Patient Case Rep Nephrol Dial, 2017.PMID 29594144