Malignant melanoma of the conjunctiva metastatic to the parotid gland: a case report.

Background: Most malignant melanomas occurring in the parotid gland are presumed to be of metastatic origin from cutaneous, sporadically mucosal, or ocular primary sites in the head and neck region. We present an unusual case of a patient with a history of conjunctival malignant melanoma and subsequent metastasis to the parotid gland.

Case presentation: A 39-year-old East Slavic male patient presented with a 6-month history of a gradually enlarging, painless swelling of the left preauricular area. The clinical examination disclosed a firm, hardly movable mass over the central part of the left parotid gland with no overlying skin changes. Fine-needle aspiration biopsy revealed a cytological image of a nonepithelial malignant tumor. Collecting a thorough past medical history unveiled that the patient underwent the surgical excision of the ipsilateral conjunctival nevus a few years earlier, with subsequent lesion recurrence and transformation into conjunctival malignant melanoma, treated with a wide local excision and an oral mucosa transplant. No signs of local melanoma recurrence or distant metastases were observed at the time of presentation. Left-sided total parotidectomy with the subsequent ipsilateral neck dissection was performed. Histopathological examination revealed melanoma metastasis to the intraparotid lymph node without extranodal extension. The patient was then qualified for adjuvant immunotherapy and remained disease-free at the 8-month follow-up.

Conclusion: In the case of a suspected malignancy within the parotid gland, exhaustive medical history taking and analysis of the patient's previous photographs might direct to the malignant melanoma diagnosis. The high potential for regional and distant metastasis in individuals with conjunctival malignant melanoma underscores the significance of ongoing research to enhance the understanding of its biological behavior and develop a standardized algorithm for its management and surveillance.