Idiopathic Acquired True Leukonychia Totalis.

Sir,

Leukonychia is opaque white discoloration of nails which may be caused by a wide array of diseases. A 14-year-old otherwise healthy well-nourished boy presented with whitening of the finger nails, since the age of 5 years. There was no history of any acute illness prior to the development of the condition. He was born out of non-consanguineous parentage and normally achieved the developmental milestones. Family history was non-contributory. He was not on any medications, systemic or topical, and not exposed to any chemical agents. Cutaneous examination showed porcelain-white nails with smooth surface. Toenails were spared. The nail bed, nail folds and the edges of the nails were normal [Figure 1]. There was no clinical evidence of atopy, alopecia areata, psoriasis or lichen planus. Rest of the mucocutaneous examination was normal. Complete biochemistry panel including routine hemogram, urine, liver function tests, renal function tests and thyroid panel were within normal limits. The nails were negative for fungus on direct examination and on culture as well. Our patient refused a nail biopsy. Based on the history and clinical findings, a diagnosis of “idiopathic acquired true leukonychia totalis” was made. The parents were counseled regarding the benign nature of the condition and the child was kept under periodic review.

Figure 1

Clinical photograph showing complete porcelain-white discoloration of the finger nails

Discussion

Leukonychia or white nails may be of four types, namely total, partial, striate or punctate. Leukonychia punctata is the most common form of leukonychia, in which small white spots appear on the nails as a result of picking and biting of the nails in young children and nail biters. Leukonychia striata or Mee's lines refers to whitening of the nail in bands that run parallel to the lunula. It may be hereditary, of traumatic origin, or associated with systemic diseases such as HIV, cirrhosis of liver or Kawasaki's, or with chemotherapeutic drugs, arsenic or lead poisoning.[1] Leukonychia totalis is whitening of the entire nail. It may be a sign of hypoalbuminaemia in renal failure, liver failure, protein-losing enteropathies or following acute illness.[2] Leukonychia partialis is whitening of parts of the nail.

Hereditary leukonychia manifests at birth or early infancy, whereas the acquired type appears in childhood. Leukonychia can be a true leukonychia involving the nail plate. In pseudo-leukonychia, onycholysis or subungual hyperkeratosis occurs due to pathology of matrix or nail bed, as in onychomycosis.

The etiopathogenesis of true leukonychia is unclear. However, it is postulated that abnormal keratinization leading to accumulation of parakeratotic cells and abnormally large keratohyaline granules may cause reflection of light and subsequent loss of nail plate transparency.[3] On an ultra-microscopic level, dissociated keratin bundles and intracytoplasmic lipid vacuoles can be seen. These dissociated layers are believed to be the main structural abnormality of the nail plate causing the white discoloration because the bundle structure is impenetrable by light and reflects all wavelengths of visible light, thus appearing white.[4] While hereditary true leukonychia is persistent and resistant to treatment, it requires genetic counselling to unearth other syndromes in a family. Leukonychia may be associated with various conditions like congenital hyperparathyroidism, hypoparathyroidism, LEOPARD syndrome, palmoplantar keratoderma, pili torti, onychorrhexis, cataracts, kidney stones, sebaceous cyst[5] and Bart-Pumphrey syndrome (leukonychia, sensory-neural deafness and knuckle pads).[6] Even rarer syndromes which have been reported include Bauer syndrome, Heimler syndrome, Lowry-Wood syndrome, FLOTCH syndrome, keratoderma-hypotrichosis-leukonychia totalis syndrome, congenital keratosis palmaris et plantaris-deafness-leukonychia totalis syndrome.[4] Removal of any treatable cause of acquired leukonychia may lead to normalization of the abnormality. None of the associations was seen in our case.

Leukonychia totalis is mostly inherited in an autosomal dominant fashion.[7] Less than ten such cases of acquired total leuchonychia have been reported in the English literature.[489] The rarity of such an entity prompted the present report.