A variant of nodular melanoma which shows some/many of the features typically seen in Spitz nevus

It can be divided into 3 categories

1. Spitz melanoma in which genetic alterations seen in Spitz nevus including HRAS mutation or fusion involving BRAF, ALK, NTRK1 or MAP3K8 can be identified
2. Spitzoid melanoma without a MAPK activating mutation
3. Spitzoid melanoma with a MAPK activating mutation involving non-V600 residues of BRAF & NRAS, MAP2K1/2, NF1 & KIT

Clinical features

While any age may be affected, the majority occur in the 2nd decade with a predilection for females

Exceptionally, cases are encountered in children

Prognosis depends upon the subtype (see abstract)

Histological features

•>5-10 mm

•Involve deep dermis or subcutis

•Asymmetrical, poorly circumscribed

•May show effacement/consumption of epidermis or ulceration

•Peripheral Pagetoid spread

•Large nodules which often show impaired maturation

•Loss of gradient with HMB45 and Ki67

•>20% Ki67 expression

•TERT promoter & PTEN mutations

•DNA copy-number variations

Differential diagnosis

Spitz nevus & atypical Spitz nevus/tumor will be discussed in a separate blog