Late-Onset Masseteric Metastasis of Malignant Melanoma in a Patient With Neurofibromatosis and Lipomatosis: A Diagnostic Challenge and Case Report.

Melanoma and neurofibromatosis (NF) are distinctly separate conditions, each characterized by unique pathophysiological processes. Nevertheless, their clinical presentations can share overlapping similarities. This report highlights a unique case involving a 68-year-old male with NF1 and lipomatosis, whose unwavering belief that a developing mass in the masseter region was benign and linked to the pre-existing diagnoses contributed to a significant delay in seeking healthcare. Consequently, this postponement resulted in the late diagnosis of disseminated malignant melanoma (stage IV, T4N0M1c). Given the patient's prognosis and poor general health, a palliative treatment plan was devised, entailing the complete excision of the masseteric mass and vertebral radiotherapy. Following a rapid and extensive progression of the cancerous lesions, the patient passed away in a palliative care infirmary four months after surgery. The significance of this case, justified not only by its uncommon presentation and atypical differential diagnosis, highlights the critical necessity of regular follow-up protocols for melanoma patients, particularly those prone to metastasis, while ensuring patient attendance. Furthermore, it underscores the necessity of patient education, particularly in recognizing early signs and symptoms, and timely intervention in cases with complex comorbidities.