The Ventral Nail

Case of cronkhite--Canada syndrome with associated jejunal diverticulosis.

“…This has been noticed in one other patient with the Cronkhite-Canada syndrome (Shuster, personal communication) and may be a feature of it. The nail dystrophy is not pathognornonic, as it has been reported in a patient with pustular psoriasis (Samman, 1961). Alopecia and generalized pigmentation were present in all previously reported cases, but though similar diffuse hair changes had occurred in the above patient increased pigmientation was absent.…”

Keratin expression in the normal nail unit: markers of regional differentiation

“…In many nail diseases, the nail plate thickens with an apparent nail bed contribution. This is particularly the case for psoriasis 33 where the nail bed can produce a ‘false nail’. It may also be relevant in pachyonychia congenita, where mutations of the genes encoding for K6a, K6b, K16 and K17 result in thickened nails.…”

Nail biology and nail science

“…Although these indices do not directly measure nail plate production, a very low index for normal nail bed is consistent with other studies suggesting that the nail bed is an insignificant player in normal nail production. The situation may change in disease and the definition of nail plate becomes difficult when substantial subungual hyperkeratosis produces a ventral nail of indeterminate character [124].…”

“…Historically, this has been referred to as the solehorn and considered a germinal element of the hyponychium. Samman considered this issue in the context of a patient with pustular psoriasis [124]. He concluded that the ventral nail is a movable feast, manifesting itself in certain pathological circumstances.…”

“…There is a high number of disulphide bonds, low content of bound sulphydryl groups, phospholipid and calcium. Controversy allows that the ventral nail plate may be a variable entity [88]. Jarrett and Spearman [86] described it as a layer only one or two cells thick.…”