In most cases, the histologic differential diagnosis was between Spitz nevus and spitzoid melanoma or between atypical nevus (such as variants of deep penetrating/clonal/inverted type-A nevus, pigmented spindle cell nevus
, atypical genital nevus, atypical conjunctival nevus showing cytologic atypia, mitotic activity, limited maturation, or proliferative nodules, among others) and nevoid melanoma (Table 1).
Variants of Spitz nevus Variants Reference Angiomatoid Spitz nevus (a) 2, 3 Atypical pigmented spindle cell nevus
(b) 4, 5 Atypical Spitz nevus (c) 4, 5 Desmoplastic Spitz nevus (d) 6, 7 Hyalinizing Spitz nevus (e) 1 Malignant Spitz nevus (f) 5, 8 Pagetoid Spitz nevus 5, 9 Pigmented spindle cell nevus
4, 10, 11 Recurrent Spitz nevus 12 Spitz nevus with florid pseudoepithelial 13 hyperplasia Spitz nevus with halo phenomenon 14 Tubular epithelioid cell nevus (g) 15 (a) Several investigators consider angiomatoid Spitz nevus to be a variant of desmoplastic Spitz nevus.
A plexiform spindle cell nevus
subsequently reported by Barnhill et al (2,3) has essentially the same histologic features.
Most variants of cutaneous nevi including combined nevus, balloon cell nevus, Spitz nevus, pigmented spindle cell nevus
, and blue nevus have been reported in the conjunctiva.