Abstract

Spitz tumors harboring fusions of NTRK3 with MYO5A have been recently described in the literature as having characteristic cytomorphology. The dermal component of these neoplasms is usually composed of predominately spindled melanocytes arranged in fascicles or nests, giving the tumors a neuroid appearance. Palisading of nuclei and formation of pseudo-Verocay bodies is sometimes present. Herein, we present a case of a 21-year-old male with an enlarging cutaneous lesion on the right neck. The patient reported the “mole” had recently been increasing in size and changing in color. Histopathologic evaluation of the initial shave biopsy showed a compound melanocytic proliferation comprised of nested epidermal and papillary dermal melanocytes. The melanocytes had a spindled morphology and a storiform growth pattern, resembling Verocay bodies, in the superficial and deep dermal components. Immunohistochemical testing showed retained expression of p16 and no expression of pan-TRK. Tissue was sent for genomic testing, and RNA sequencing identified a MYO5A::NTRK3 chromosomal rearrangement. No other significant genomic findings were identified. These histopathologic and genomic findings favor a benign neoplasm of Spitz lineage and appear consistent with more recently characterized Spitz tumors harboring MYO5A::NTRK3 fusions. It is our aim to add to the growing literature of similar cases to help in better recognition and management.