Discussion:
Glabrous skin of palm and the papillary ridges is characterized by
absence of hair follicles and sebaceous glands. Hairy skin complications
are frequent in VKHD. Integumentary changes like alopecia, poliosis and
vitiligo are late complications in this disease. The presence of vellus
hairs on palm similar to cheeks have been
demonstrated.7 Melanocytes are found in meninges and
inner ear in addition to eye, skin and hairs. The pathogenesis of VKHD
though not completely understood, involves auto antigens, the melanocyte
differentiation proteins, like tyrosinase (TYR), tyrosinase-related
peptide (TRP)-1, TRP-2.8,9 These proteins are the
enzymes involved in the synthesis of melanin and are present
specifically in melanocytes.10 Additional auto
antigens, like KU-MEL-1 and lens epithelium-derived growth factor have a
role through an IgG-mediated mechanism.9 The genetic
predisposition involves certain genetic or epigenetic factors resulting
in immune dysregulations.11 The growth of hairs on
palmer surface of distal phalanx of the thumb may be the result of auto
antigens along with immune dysregulations.