Discussion
The mechanism of leukonychia is not clear .True leukonychia is thought
to result from abnormal keratinization of the distal matrix that causes
parakeratosis in the ventral nail plate. Retained keratohyalin granules
in the nail plate cells reflect light and cause subsequent loss of nail
plate transparency. [2,4]
Leukonychia totalis and partialis can be inherited as an isolated
finding or as part of a syndrome or can be acquired. Hereditary
leukonychia has been found to be associated with peptic ulcer disease
and cholelithiasis, congenital hyperparathyroidism, hypoparathyroidism ,
cataracts, acanthosis nigricans, pili torti , severe keratosis pilaris ,
recurrent sebaceous cysts and renal calculi as well as in Bart-Pumphrey
syndrome (leukonychia, sensory-neural deafness and knuckle pads),
Heimler syndrome, Lowry-Wood syndrome, FLOTCH syndrome,
keratoderma-hypotrichosis-leukonychia totalis syndrome, congenital
keratosis palmaris et plantaris-deafness-leukonychia totalis syndrome,
Bauer syndrome and LEOPARD syndrome.[1-4] Acquired leukonychia can
occur due to psoriasis, onychomycosis, local trauma, alopecia areata or
systemic illness like cardiac insufficiency, myocardial infarction,
renal failure, pleural empyema, liver diseases, protein-losing
enteropathies, systemic infections, sickle cell anemia, systemic lupus
erythematous, malnutrition, chemotherapeutic exposure, heavy metal
poisoning.[2-4] Removal of cause of acquired leukonychia may lead to
resolution of white colour. Sometimes, cause is unknown as in our case.
Idiopathic acquired true leukonychia totalis and leukonychia partialis
is a rare condition. Literature review shows that nineteen cases have
been reported till date [1-3, 5-18], none reported from Nepal