Dermatoses Causing Leukonychia

All conditions leading to onycholysis also cause apparent leukonychia. Psoriasis may
cause both true and apparent leukonychia. True leukonychia is due to matrix
involvement, and apparent leukonychia to onycholysis and/or parakeratosis of the nail
bed. One of the earliest signs of leprosy is apparent macrolunula, which may become
total in dystrophic leprosy.

Table 7.1 Causes of leukonychia
Congenital and/or hereditary
Isolated
Acrokeratosis verruciformis (Hopf)
Associated with koilonychia
LEOPARD syndrome (lentigines, electrocardiographic changes, ocular hypertelorism, pulmonary stenosis, abnormalities of genitalia, retarded growth, deafness)
Associated with deafness
Leukonychia totalis, multiple sebaceous cysts, renal calculi
Darier’s disease—usually linear and longitudinal
Acquired
Pseudoleukonychia
Diffuse form of distal and lateral subungual onychomycosis
Proximal white subungual onychomycosis, especially in AIDS patients
Superficial white onychomycosis
Keratin granulation (superficial friability from nail varnish)
Psoriasis
Apparent leukonychia (Figure 7.9)
Anaemia
Cancer chemotherapeutic agents
Cirrhosis (Terry’s sign)
Dyshidrosis
Half-and-half nail (renal diseases) and distal crescent pigmentation
Leprosy
Muehrcke’s lines of hypoalbuminaemia
True leukonychia
Alkaline metabolic disease
Alopecia areata
Carcinoid tumours of the bronchus
Cardiac insufficiency
Cytotoxic and other drugs (emetine, pilocarpine, sulphonamide, cortisone)
Erythema multiforme
Exfoliative dermatitis
Fasting periods (e.g. in orthodox Jews and Muslims)
Fracture
Gout
Hodgkin’s disease
Hypocalcaemia
Infectious diseases and infectious fevers
Intra-abdominal malignancies
Kidney transplant
Leprosy
Leuko-onycholysis paradentotica
Menstrual cycle
Myocardial infarction
Occupational
Pellagra
Peripheral neuropathy
Poisoning (antimony, arsenic, fluoride, lead, thallium)
Protein deficiency
Psoriasis
Psychotic episodes (acute)
Renal failure (acute or chronic)
Shock
Sickle cell anaemia
Surgery
Sympathetic leukonychia
Trauma (single or repeated)
Tumours (benign), cysts pressing on matrix
Ulcerative colitis
Zinc deficiency

Leukonychia may also occur in other dermatoses affecting the matrix, such as alopecia areata, dyshidrosis, Darier’s disease and Hailey-Hailey disease. Table 7.1 lists many of the causes and factors leading to leukonychia.

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