Fine‐needle aspiration cytological findings in three cases of metastatic amelanotic melanoma to the parotid gland with divergent differentiation

Abstract

This report presents the clinical and pathologic findings of three cases of metastatic amelanotic melanoma to the parotid gland. Two of the patients had a primary cutaneous tumor. Fine‐needle aspiration of the parotid showed clusters of epithelioid cells and/or spindle‐shaped cells with vesicular nuclei, macronucleoli, and abundant eosinophilic cytoplasm. In addition, one had striking balloon‐cell features. In the immunohistochemical study, the tumors expressed S‐100, HMB‐45 antigen, Melan‐A, and SOX10, and focally smooth‐muscle actin, cytokeratin, CD56, p63, and synaptophysin. The diagnosis was challenging because the tumors were clinically thought to be primary parotid lesion and showed unusual immunohistochemical labeling for SMA, cytokeratins, p63, and neuroendocrine markers. Furthermore, the long clinical history in two of the cases made the diagnosis of a metastatic lesion less likely. Diagnostic errors can be reduced by integrating cytomorphologic, histologic, immunohistochemical, and clinical findings.

Mimickers of neuroendocrine tumors on endoscopic ultrasound‐guided fine‐needle aspirate material: Need for caution

“…10 In addition, partial loss of melanocytic markers along with expression of neuroendocrine markers is not uncommon in malignant melanomas. [11][12][13][14] In case #3, we were able to give a diagnosis of glomus tumor on the aspirate specimen. The monotonous nature of lesional cells, their cohesiveness, distinctive hemangiopericytoma-like vascular pattern and characteristic immunostain profile (INSM1, chromogranin and cytokeratin negative, and calponin and SMA positive) helped distinguish glomus tumor from a well-differentiated neuroendocrine tumor.…”

“…It is noted that synaptophysin expression can be found in 29% of malignant melanomas, 9 since melanoma cells contain neurosecretory granules as demonstrated on electron microscopy 10 . In addition, partial loss of melanocytic markers along with expression of neuroendocrine markers is not uncommon in malignant melanomas 11–14 …”

Is Primary Poorly Differentiated Sarcomatoid Malignancy of the Parotid Gland Sarcomatoid Undifferentiated/Dedifferentiated Melanoma? Report of Three Unusual Cases Diagnosed by Fine-Needle Aspiration Combined with Histological, Immunohistochemical, and Molecular Analyses

“…Metastases to the salivary glands from known cutaneous, mucosal, or ocular melanoma are relatively common and may be confidently diagnosed using fine-needle aspiration (FNA) [1]. When the primary cutaneous tumor undergoes spontaneous regression, the diagnosis is more difficult, especially in amelanotic forms [2][3][4][5][6].…”

“…However, differentiation between primary and metastatic melanoma is important, but not always easy. It was established [20,21] that to differentiate between primary and metastatic melanoma, morphological requirements are: (1) the tumor should be localized to the parenchyma of the parotid gland; (2) there should be no identifiable lymph node structures present within the tumor; (3) there should be no evidence of melanoma elsewhere after a diligent search of the eyes, skin, nose, pharynx, mouth, esophagus, anogenital region, and meninges; and (4) there should be no evidence of previous excision of a melanoma or regression of a pigmented lesion.…”