What is phrynoderma?
Phrynoderma is a form of follicular hyperkeratosis associated with nutritional deficiency.
Who gets phrynoderma?
Phrynoderma is most often reported in children living in poverty in Africa and Asia.
A dietary history may reveal:
- Prolonged history of poor dietary intake in the past 1–2 years
- Lack of vegetables, fruit and fat in the diet.
It is rare in developed countries, when it is most often associated with:
- Intestinal malabsorption
- Anorexia nervosa
- Fad diets
- Previous bariatric surgery or small bowel bypass surgery
- A history of alcoholism
Phrynoderma is associated with other chronic illnesses, such as pancreatic insufficiency, inflammatory bowel disease, and gallbladder disease [1, 3, 4].
What causes phrynoderma?
Phrynoderma is associated with nutritional deficiency, particularly:
- Vitamin A deficiency (commonly)
- Severe malnutrition
- Vitamin E and B deficiency
- Essential fatty acid deficiency [1, 2].
What are the clinical features of phrynoderma?
Phrynoderma is a form of asymptomatic or mildly symptomatic follicular hyperkeratosis in which follicular papules of various sizes develop on the skin with central keratotic plugs . New patches may be hypopigmented .
Patches initially arise on the extensor aspects of the elbows and knees. They can spread to involve the extremities, upper forearms and thighs.
Occasionally patches will appear on the abdomen, back and buttocks. The face is rarely affected, and hands and feet are spared .
Other symptoms of vitamin A deficiency may be present such as:
- Night blindness
- Inability to see in bright light.
Features of severe vitamin A deficiency may include:
- Xerophthalmia (dryness of the conjunctiva and cornea of the eye with inflammation and ridge formation)
- Bitot spots (grey-white patches on the conjunctivae)
- Keratomalacia (drying and clouding of the cornea) which can lead to blindness
- Growth and mental retardation .
What are the complications of phrynoderma?
Phrynoderma may result in persistent hyperpigmentation or scarring.
How is phrynoderma diagnosed?
Phrynoderma may be suspected in the right context by its characteristic clinical features. If skin biopsy is performed, histological features may include:
- Dilated hair follicles containing keratin plugs
- Lamellated hyperkeratosis adjacent to hair follicles
- Atrophy of sebaceous glands
- Keratinising metaplasia of epithelial surfaces
- Squamous metaplasia of eccrine and sebaceous glands in severe disease [1, 3].
The level of vitamin A in the blood of patients with phrynoderma may be low (< 30 ug/100 ml) or normal. Levels may not reflect clinically apparent deficiency, as stores may last up to a year in adults . Severe malnutrition is associated with reduced albumin levels.
The diagnosis of phrynoderma is supported if the signs resolve with better nutrition .
What is the differential diagnosis of phrynoderma?
Several other conditions are characterised by follicular hyperkeratosis.
- Keratosis pilaris (upper arms, lateral thighs of healthy individuals)
- Keratosis follicularis (a sign of Darier disease affecting hands and seborrhoeic areas, including the forehead, scalp, nasolabial folds, ears and chest).
- Lichen spinulosus (an acute eruption of grouped keratotic papules)
- Keratosis circumscripta (a follicular form of ichthyosis)
What is the treatment for phrynoderma?
Patients with phrynoderma may be assessed by a nutritionist, dietician, ophthalmologist, dermatologist, gastroenterologist and/or general physician.
Nutritional management may include:
- Vitamin A replacement: 50,000–150,000 U/day for 1–4 months 
- Vitamin A-rich foods, such as liver, carrot, spinach, egg yolk
- Supplemental linoleic acid using safflower or linseed oil (2 tbsp twice daily)
- Other supplementation according to dietary assessment.
Topical keratolytic agents may be applied to the scaly plaques for symptomatic relief.
What is the outcome of phrynoderma?
Skin lesions can take one to four months to resolve with restoration of nutrition, but topical keratolytics can provide temporary relief .
Vitamin A deficiency can cause ocular disturbance, but this generally resolves within days of starting therapy, unless scarring has occurred. If left untreated there can be permanent scarring of the conjunctiva and cornea .