Metastatic malignant melanoma mimicking a salivary gland basaloid neoplasm after treatment with nivolumab

Abstract

Malignant melanoma is a well‐known diagnostic pitfall, given its propensity to metastasize to different sites and mimic various entities. In this report, we present a fine‐needle aspiration biopsy (FNA) of a metastatic melanoma with basaloid features that is occurring in the preauricular/parotid area. The patient is a 17‐year‐old male with a history of excision of melanoma of the left temple, and was undergoing adjuvant treatment with nivolumab. The prior excision was positive for S100, HMB‐45, melan‐A, and tyrosinase. On follow‐up, he presented with non‐FDG avid left preauricular area lesions. FNA was performed, and on‐site evaluation demonstrated a cellular basaloid neoplasm with focal fibrillary stroma. Immunohistochemical stains revealed that the tumor cells were positive for SOX‐10, S100, MITF, and HMGA2, and were negative for HMB‐45, melan‐A, tyrosinase, p63, cam 5.2 and PLAG1. The positive S100, SOX‐10, and MITF results and negative cam 5.2 result supported the diagnosis of melanoma. Nivolumab was then stopped, Dabrafenib/Trametinib were started, and the patient underwent excision of the nodules. Nine‐months later, he developed a rib metastasis that was positive for S100, SOX‐10, melan‐A, and tyrosinase. This report emphasizes that melanoma involving the parotid gland region has the potential to be misdiagnosed by FNA as a salivary gland neoplasm because of overlapping cytologic features and immunophenotypes. This pitfall is avoided by careful morphologic analysis and judicious use of ancillary studies.

Circular RNA ZNF609 drives tumor progression by regulating the miR-138-5p/SIRT7 axis in melanoma

“…Melanoma is a prevailing malignant skin cancer with high metastasis incidence and aggressive mortality, and the melanoma occurrence rate continues to increase globally [1][2][3]. In recent years, therapeutic strategies have advanced, but the prognosis of melanoma patients remains poor due to radiotherapy or chemotherapy resistance and metastasis [4].…”