Fig. 13: In this portion of the vertical growth component, spindle cells form closely spaced nests and fascicles (pattern of typical vertical growth). The cytologic features are monotonous; nuclei are intermediate in size. They show some variation in size, staining and outlines. Chromatin is delicate and marginated (nuclear membranes are "heavy"). Nucleoli are inconspicuous. Inflammation is not a prominent feature. There are two mitotic figures (blue arrows).

Fig. 14: The vertical growth component is composed of loosely spaced fascicles and nests of melanocytes; the pattern in this field qualifies as variant vertical growth. The vertical growth  component is relatively free of lymphoid infiltrates. Near the bottom of the field, nests of plump epithelioid melanocytic cells are associated with lymphoid inifiltrates. The patterns in this area are halo nevus-like; even the cytologic features of the plump epithelioid cells are halo nevus-like. Blue arrows outline a nests of these cells and lymphoid cells are sprinkled among the epithelioid cells (lymphomelanocytic island of halo nevus phenomena.

Fig. 15a: (see Fig. 9 for approximate location of this field. In the dermal component the atypia is mild to moderate. Chromatin patterns are open and some of the nuclei contain small nucleoli. Nests of more common nevus cells are represented at the top of the field. This dermal component, as seen in Fig. 9 has tumoral qualities; it has features of a vertical growth component.  There is a mitotic figure (red arrow). This component might be characterized as dermal melanocytic dysplasia of halo nevus-like type, or as a most differentiated minimal deviation melanoma of halo nevus-like type, dermal variant. The patterns are indiscriminate; the lesion in this field qualifies as melanocytic neoplasia of indeterminate malignant potential.

Fig. 15b:In this field, a nest of plump, epithelioid melanocytic cells are loosely spaced; lymphoid cells have infiltrated among the epithelioid cells to form a lymphomelanocytic nests as seen in the setting of halo nevus and halo nevus-like phenomena. The plump cells are cytologically uniform. Nuclei are somewhat eccentric and show delicate chromatin patterns. Patterns of this type may be encountered in the setting of halo nevus. Some examples of MDM of halo nevus type, dermal variant may show a preponderance of this type of cell in its vertical growth component. A MDM of halo nevus type, dermal variant, showing epithelioid cells in vertical growth is closely related histologically and biologically to MDM of dermal type. Distinctions must be based on the identification of halo nevus phenomena at the margin of the vertical growth component, particularly in any remnant of preexisting nevus.

Fig. 15c: In contrast to the epithelioid cells as seen in the halo nevus remnant in Fig. 15b, the cells of the main vertical growth component are spindle shaped; the cells probably have evolved from a population of dysplastic cells at the dermal-epidermal interface rather than evolving as an in situ transformation of a dermal component. Both options are available in the evolution of MDM of the halo nevus-like type.