This is commonly regarded as a variant of Spitz nevus but as it has such disctinct histological features it is covered in a separate blog.

Clinical features

•Heavily pigmented papule or nodule, starburst pattern seen with dermoscopy is characteristic

•Young people

•F>M

•Lower limbs> upper limbs> trunk

Histological features

•Variant of Spitz nevus, readily identifiable at scanning magnification in the majority of cases

•Symmetrical and circumscribed with a characteristically flat lower border

•Vertically orientated oval junctional nests

. Heavy pigmentation although hypopigmented/amelanotic varinats can be encountered

•Junctional or compound

•Acanthosis & hyperkeratosis

•Maturation in compound variants

•Spindle cells with small nucleoli

•Mild pleomorphism

•Kamino bodies

•Central focal Pagetoid spread & elimination of nests sometimes seen

•Junctional mitoses

•Adnexal involvement

. Lymphocytic infiltrate often seen at base

•80 % kinase fusions (NTRK3-58%), HMB45 diminishes with depth in compound lesions