Dermatology, Venereology and Leprosy
Nutritional Deficiencies and the Skin
Nutritional skin disease for MBBS and NEET-PG: vitamin A phrynoderma, pellagra and Casal's necklace, scurvy, and zinc-related acrodermatitis enteropathica, mapped to NMC codes DR17.
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Nutritional Deficiencies and the Skin
Nutritional skin disease for MBBS and NEET-PG: vitamin A phrynoderma, pellagra and Casal's necklace, scurvy, and zinc-related acrodermatitis enteropathica, mapped to NMC codes DR17.
Nutritional deficiencies leave recognisable marks on the skin, hair and mucosae. This chapter covers the cutaneous features of vitamin A deficiency, the B-vitamin syndromes including pellagra with Casal's necklace, scurvy from vitamin C deficiency, and zinc deficiency with acrodermatitis enteropathica, together with their correction by replacement.
High-yield: Nutritional Deficiencies and the Skin
- Nutritional deficiencies often show characteristic skin, hair and mucosal changes that can be the first clue to malnutrition.
- Vitamin A deficiency causes follicular hyperkeratosis with dry rough skin (phrynoderma) and, in the eye, night blindness and Bitot's spots.
- Niacin (vitamin B3) deficiency causes pellagra, remembered as the three Ds of dermatitis, diarrhoea and dementia.
- The pellagra rash is photosensitive and forms a well-demarcated pigmented band around the neck called Casal's necklace.
- Riboflavin (vitamin B2) deficiency causes angular stomatitis (cheilosis), glossitis and a scaly seborrhoeic-like dermatitis.
- Pyridoxine (vitamin B6) deficiency causes seborrhoeic dermatitis, cheilosis, glossitis and can be precipitated by isoniazid.
- Vitamin B12 and folate deficiency can cause glossitis and hyperpigmentation, particularly over the knuckles.
- Vitamin C deficiency causes scurvy with perifollicular haemorrhage, corkscrew hairs, swollen bleeding gums and poor wound healing.
- Scurvy reflects the role of vitamin C in collagen synthesis, so blood vessels and connective tissue become fragile.
- Zinc deficiency causes acrodermatitis enteropathica with a periorificial and acral eczematous rash, diarrhoea and alopecia.
- Acrodermatitis enteropathica may be inherited or acquired and responds well to zinc supplementation.
- Protein-energy malnutrition, as in kwashiorkor, causes flaky-paint dermatosis, oedema and hair changes with a reddish tint.
- Recognising these patterns allows the dermatologist to point to a specific deficiency and its correction.
- Treatment is replacement of the deficient nutrient along with correction of the underlying dietary or absorptive cause.
Nutritional skin syndromes
- **Vitamin A:** Follicular hyperkeratosis (phrynoderma), night blindness, Bitot's spots.
- **Niacin (B3):** Pellagra: dermatitis, diarrhoea, dementia; Casal's necklace.
- **Vitamin C:** Scurvy: perifollicular haemorrhage, corkscrew hairs, bleeding gums.
- **Zinc:** Acrodermatitis enteropathica: periorificial rash, diarrhoea, alopecia.
NMC competencies in this chapter
- **DR17.1:** Skin changes in vitamin A deficiency
- **DR17.2:** Skin changes in vitamin B complex deficiency
- **DR17.3:** Skin changes in vitamin C deficiency
- **DR17.4:** Skin changes in zinc deficiency
Frequently Asked Questions
What are the three Ds of pellagra?
Dermatitis, diarrhoea and dementia, from niacin deficiency. The rash is photosensitive and can form a pigmented band around the neck called Casal's necklace.
What skin signs does scurvy produce?
Perifollicular haemorrhage, corkscrew hairs, swollen bleeding gums and poor wound healing, reflecting the role of vitamin C in collagen synthesis and vessel integrity.
What is acrodermatitis enteropathica?
A syndrome of zinc deficiency with a periorificial and acral eczematous rash, diarrhoea and hair loss, which may be inherited or acquired and responds to zinc replacement.
How is the eye affected by vitamin A deficiency?
It causes night blindness and Bitot's spots, alongside the follicular hyperkeratosis of the skin known as phrynoderma.
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