Fig. 2

SF3B1 mutation in primary leptomeningeal melanoma in a patient with neurocutaneous melanocytosis. a. H&E staining of the primary LMN diagnosed as melanoma; the arrows indicate mitotic figures (patient #21). b. H&E staining of the congenital melanocytic nevus of the buttocks; in the right lower corner higher magnification of the superficial part of the nevus with a proliferation of bland nevoid cells. c. BAP1 immunostaining of the melanoma depicted in (a) with nuclear staining in more than 90 % of tumor cells. d. Sequence tracing surrounding codon 61 of NRAS showing a c.182A > G (p.(Gln61Arg)) mutation present in both the CNS melanoma as well as in the congenital melanocytic nevus (reverse sequence/antisense strand). e. Forward sequence tracing surrounding codon 625 of SF3B1 showing a c.1874G > A (p.(Arg625His)) mutation in the CNS melanoma. f. The SF3B1 mutation depicted in (e) is absent in the congenital melanocytic nevus of this patient