Meningeal melanomatosis: a challenge for timely diagnosis

Neoplastic meningitis is a central nervous system complication that occurs in
3-5% of patients with cancer. Although most commonly seen in patients with
disseminated disease, in a small percentage of patients, it may be the initial
manifestation of cancer or even primitive in origin. In the absence of cancer
history, the diagnosis of neoplastic meningitis may be challenging even for
expert neurologists. Prognosis is poor, with a median overall survival of weeks
from diagnosis. In the retrospective study herein, we described three cases of
meningeal melanomatosis in patients without previous cancer history. The patients
were diagnosed with significant delay (17 to 47 weeks from symptom onset) mainly
due to the deferral in performing the appropriate testing. Even when the
diagnosis was suspected, investigations by MRI, cerebrospinal fluid, or both
proved at times unhelpful for confirmation. Prognosis was dismal, with a median
survival of 4 weeks after diagnosis. Our observations are a cue to analyze the
main pitfalls in the diagnosis of neoplastic meningitis in patients without
cancer history and emphasize key elements that may facilitate early diagnosis.