Fig. c5t3P1: In the subsequent photomicrographs, a common feature is an expansile nodule in association with cytologic atypia. This combination was basic to the diagnosis of MDM variants, including the Spitz-like type. The expansile nodule in this example shows a level III pattern; it is confined to a widened papillary dermis. Focally, the nodule is associated with lymphoid infiltrates. To the right, the patterns in the widened papillary dermis do not  contribute to the nodule; a remnant of a earlier stage of neoplasia  is represented in this area.

Note: In the definition of MDM, a vertical growth component of typical type was a requisite. Subsequently, some lesions with high grades of nuclear atypia, but showing variant and migrant vertical growth-like patterns, were also included in the “Spitz-like” category. Atypia generally is more prominent in the “Spitz-like  category” than in the other MDM  categories.

Fig. c5t3P2: The lesion of fig. c5t3P1 is represented at higher  magnification. The area to the right more closely resembles a  classical “Spitz nevus.” In the nodule to the left, atypia is more prominent than in the component to the right; comparisons between the nuclear qualities of the two sites establishes discordance. This is classical MDM of “Spitz-like” type.

Fig. c5t3P4:The cytologic features are disturbing. Atypia is marked. There is nuclear pleomorphism. The lesion has nodular qualities. This is a recurrence of the lesion represented in fig. c4t3P7. Commonly,  recurrent “Spitz nevi” are more atypical than the primary  lesion.

Fig. c5t3P5: This lesion is sufficiently atypical and tumoral to qualify as MDM of “Spitz nevus-like” type. Lymphoid infiltrates are  moderate. Fascicles are loosely spaced but the overall configuration was expansile.