A. Tosti et al., NAIL MATRIX NEVI - A CLINICAL AND HISTOPATHOLOGIC STUDY OF 22 PATIENTS, Journal of the American Academy of Dermatology, 34(5), 1996, pp. 765-771
Background: Because most dermatologists do not regularly perform biops
ies of longitudinal melanonychia, even when the pigmentation presents
as a single band, the true prevalence of nail matrix nevi is unknown.
Objective: Our purpose was to determine the prevalence of nail matrix
nevi in white patients with longitudinal melanonychia involving a sing
le digit and to determine whether longitudinal melanonychia caused by
a nail matrix nevus can be clinically distinguished from longitudinal
melanonychia from other causes. Methods: From January 1989 to December
1994 we performed a nail biopsy on 100 of 128 consecutive white patie
nts who had a single band of ''idiopathic'' longitudinal melanonychia.
Results: A nail matrix nevus was detected in 22 patients, A junctiona
l nevus was found in 19 specimens and a compound nevus in three specim
ens. Conclusion: Nail matrix nevi in Caucasian patients are uncommon b
ut not exceptional. The number of nevi presenting with longitudinal me
lanonychia exceeded that of melanoma. The diagnosis of nail matrix nev
i is impossible clinically and always requires histopathologic study.
The pathologic features of nail matrix nevi are similar to those of sk
in nevi except for their architectural pattern, which reflects the pec
uliar anatomy of the nail unit.