BAP1 失活性黑色素细胞肿瘤中发生的侵袭性黑色素瘤伴 NRAS 突变：一例特殊病例报告并着重其基因组特征及文献复习

BAP1-inactivated melanocytic tumor is a distinct entity with loss of BAP1 protein and epithelioid morphology. It shares histopathologic features with Spitz nevus and nevoid melanoma, and it can occur sporadically or with germline BAP1 predisposition syndrome. These lesions typically have tumor-infiltrating lymphocytes and infrequent mitoses. They are generally indolent, though melanoma can arise in both germline and sporadic cases. Most show BRAF V600E and BAP1 mutations.

We describe four tumors in one patient diagnosed with BAP1-tumor predisposition syndrome (BAP1-TPDS): two invasive melanomas arising in BIMT and two BIMTs with uncertain malignant potential. Molecular analysis and fluorescence in situ hybridization (FISH) revealed BAP1 and NRAS mutations in melanoma and BAP1-inactivated melanocytic tumor components, with a gain of 6p25 (RREB1) in the melanoma component only.

The patient completed pembrolizumab adjuvant therapy with no evidence of metastasis. This is a rare presentation of BIMT with BAP1 and NRAS mutations, absence of BRAF V600 mutation, and loss of BAP1 immunoreactivity in all lesional cells.

Our case adds to the understanding of the histomorphologic and mutational spectrum in BAP1-inactivated melanocytic tumors.