Fine needle aspiration of malignant melanoma with myxoid features: A case report with molecular analysis

Abstract

Malignant melanoma with myxoid features (MMM) is a rare melanoma variant in which tumor cells are embedded within a basophilic myxoid stroma. The stromal matrix is composed of acidic mucopolysaccharides, which are thought to be produced by mesenchymal stromal cells in response to melanoma invasion. Interestingly, this myxoid matrix is more often seen in metastasis from a primary tumor that does not have a myxoid stroma. The diagnosis of MMM on fine needle aspiration (FNA) can be confused with other myxoid tumors. Herein, we present a case of MMM diagnosed by FNA of a peri‐auricular lymph node in an 89‐year‐old man with a history of resected malignant melanoma. We describe the clinical, cytohistological, and immunohistochemical findings, and present the unique molecular alterations that were identified. We also discuss the differential diagnosis and potential diagnostic pitfalls associated with MMM.

Case report: Malignant melanoma of the lower limb with gastric metastasis

“…For microscopic diffuse heteroid cells, in addition to the primary poorly differentiated gastrointestinal carcinoma, we should consider small cell carcinoma, neuroendocrine carcinoma, lymphoma, rare myeloid cell sarcoma, and MM ( 15 ). Immunohistochemical examination was helpful for differentiation; for example, the diagnostic specificity and sensitivity of the immunohistochemical index HMB45 for malignant melanoma were 100% and 93%, and the S-100 protein has a strong response to oligopigmented or amelanotic malignant melanoma ( 16 ).…”

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

“…This is especially so in instances where the melanoma shows a basaloid morphology, and as shown in this case, metachromatic matrix production. Fibrillary matrix production by melanoma is uncommon, but has been noted in the cytology of malignant melanoma with myxoid features 7,8 . SOX‐10 and S100 IHC positivity is typical of melanoma, but is also seen in several basaloid salivary gland neoplasms, including pleomorphic adenoma, myoepithelioma, myoepithelial carcinoma, epithelial myoepithelial carcinoma, polymorphous adenocarcinoma, and adenoid cystic carcinoma.…”