Timothy C. Hain, MD • Page last modified: August 22, 2020
Melanomas are a rare tumor that can cause hearing decline and vertigo. Their main problem is that they metastasize, and they can be difficult to distinguish from "moles".
Melanoma's make up about 5 to 8% of all malignancies. They mainly affect the skin but they can also arise from or be metastatic to the area of the ear. Metastases can occur as long as 17 years after removal of a cutaneous melanoma ! (Brackman and Doherty, 2007). According to Chang (2015), more than half of all reported cases of metastatic lesions to the internal auditory canal are bilateral. (Chang and Michaelides, 2015).
Factors suggesting the diagnosis are a history of melanoma, MRI findings and a cerebellopontine angle syndrome with rapid progression of symptoms (Oluigbo et al, 2006; Brackman and Doherty, 2007).
Metastatic melanoma's usually present with bilateral findings (Tu et al, 1994; Brackman and Doherty, 2007). Tumors that are metastatic to the internal auditory canal are commonly bilateral (Chang and Michaelides, 2015).
There are two MRI patterns. Pigmented melanoma's are hyperintense on T1, similar to a lipoma, but do not decrease as normal in signal with fat suppression sequences, and is hypointense or isointense on T2. They enhance with contrast.
Nonpigmented melomas are isointense on T1 and variable on T2, and enhance with contrast, resembling an acoustic neuroma (Piedra et al, 2006).
The diagnosis of metastatic melanoma can be confirmed via lumbar puncture.
The prognosis of metastatic melanoma is poor because in this case there are tumor cells throughout the coverings of the brain (Arriaga, 1995). As of 2007, median survival time was about 12 months (Brackman and Doherty, 2007).
Primary melanoma can be treated surgically with more success.