Parotid Gland Primary Amelanotic Malignant Melanoma

Abstract

Primary malignant melanomas (MMs) of the parotid gland are extremely rare. Only a few cases have been published in the literature; also, only one report has been published regarding a primary amelanotic malignant melanoma (AMM) of the parotid gland. AMM is an extremely rare tumor, and immunohistochemical analysis is needed to differentiate the diagnosis.In this report, we present an AMM in the parotid gland, with no other primary lesions detected. Case ReportAn 80-year-old man presented to our clinic in December 2013 with a very large, painless, round, hard, fixed mass in the right parotid region that had been present for five months and had recently increased rapidly in size, accompanied by bleeding and a bad smell (Figure 1). Informed consent was obtained from the patient.Four months previously, the patient had presented to another clinic with a painless mass in the right parotid region. There was no skin lesion at that time. A fine needle biopsy was performed. The pathology results indicated that the mass was a malignant tumor, and the surgeon suggested total parotidectomy; however, the patient was afraid of surgery and did not seek medical attention again until the mass started to bleed. Physical examination revealed a hard, bleeding, malignant mass which was attached to the underlying soft tissue.Cervicofacial magnetic resonance imaging (MRI) showed a parotid mass measuring 82 × 43 × 34 mm with an undefined boundary. Also, the MRI showed pathological cervical nodes, the largest of which was measured to be 16 × 12 mm (Figure 1).There was no functional impairment of the facial nerve.The patient's laboratory results were normal. Subsequently, the patient underwent an incisional biopsy. Histopathological examination of the specimen fixed in buffered formalin along with immunohistochemical analysis confirmed the lesion to be an AMM. Microscopically, there was no evidence of a lymph node structure in the main tumor. The melanocytes formed groups and invaded the parotid tissue. The tumor cells had enlarged hyperchromatic nuclei with prominent nucleoli (Figure 2).Immunohistochemical expression of S100 protein and human melanoma black 45 (HMB45) analysis gave positive results, while expression of cytokeratin (CK-10) was positive in some areas. Parotid Gland Primary Amelanotic Malignant MelanomaAmelanotic malignant melanoma (AMM) represents only 2%-8% of all malignant melanomas, and primary AMM of the parotid gland is very rarely diagnosed. This is the second case of primary AMM of the parotid gland in the literature. The aim of this report is to discuss our case and this rare entity. The detection of AMM is very complex because the pathology results can be confused with those for inflammatory processes and benign and malignant tumors. Immunohistochemical analysis of S100 protein and human melanoma black 45 (HMB45) analysis provides guidance in the differential diagnosis of AMM. In this report, we present a rapidly growing amelanotic malignant melanoma in the parotid gland. Examination of the patient and radiological...

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

“…Several cases of primary melanoma of the salivary glands have been already published. Critical analysis of this literature has not provided convincing evidence that all previous cases were of primary nature [20,[26][27][28][29][30][31][32][33][34][35]. The main arguments have been the lack of immunohistochemistry in older publications (especially in amelanotic forms) or the lack of a systematical search for a potential primary tumor elsewhere.…”