A Case of Non-pigmented Malignant Melanoma Developing Cancer Meningitis and Brain Metastasis during Vemurafenib Administration

Abstract

A 75-year-old woman presented with a red hemorrhagic tumor on her right heel in 2013. The tumor was surgically excised in 2014. Then she was admitted to our hospital with the diagnosis of malignant melanoma. After a wide excision of the primary tumor, pelvic-inguinal lymph node dissection, and DAVFeron (dacarbazine, nimustine, vincristine, and interferon-β) therapy, skin, liver, lungs, and pelvic bone mestases were appeared in 2015. Nivolumab administration was started to treat the metastases, but its effect was poor in limiting tumor progression and vemurafenib administration was started. The metastases in the skin, lungs, liver, and pelvis rapidly regressed, but some bone metastases remained. At three months after the administration, disorientation, loss of appetite, and fluctuations appeared. Computed tomography and magnetic resonance imaging (MRI) of the head showed no abnormal findings. At four months after administration, loss of consciousness appeared and cancer meningitis and brain metastasis were diagnosed by contrast-enhanced MRIand cerebrospinal fluid cell examination. She died two weeks after admission. Because vemurafenib hardly reaches the brain, it has little effect on central nervous system metastases. In addition, the brain metastasis was not detected by non-contrast-enhanced MRI in this case because of the non-pigmented type of malignant melanoma. Therefore, the use of contrast-enhanced MRI was necessary for detecting the brain metastasis.