Table 5 Histopathological criteria for atypical Spitz tumors

 Diameter in mm (≥10 mm considered abnormal)

 Depth in mm (involvement of subcutaneous fat considered abnormal)

 Ulceration

 Poor circumscription

 Pagetoid melanocytosis over a large front

 Prominent confluence of melanocytes

 High cellular density

 Lack of zonation and maturation

 Asymmetry

 Few or no dull pink (Kamino) bodies

Proliferational criteria

 Significant mitotic rate—>2–6/mm²

 Deep/marginal mitoses

 Proliferation index, that is, Ki-67 expression

Between 2 and 10% (Vollmer)

≥10% (Kapor et al³⁸)

Cytological criteria

 Granular vs ground glass cytoplasm

High nuclear to cytoplasmic ratios

Loss of delicate or dispersed chromatin patterns

Thickening of nuclear membranes

Hyperchromatism

Large nucleoli