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