Ophthalmoplegia in a Her2+ and β-hCG+ Patient With Leptomeningeal Carcinomatosis Secondary to Gastric Adenocarcinoma

Leptomeningeal carcinomatosis (LMC) is an uncommon and devastating late complication of metastatic malignancy that carries a poor prognosis, typically faring worse when secondary to solid tumors. Diagnosis of LMC can be challenging, especially if the underlying cancer is undiagnosed, as presenting symptoms can be nonspecific or involve focal deficits such as cranial nerve palsies. Typically, LMC can be recognized due to new central neurological findings with concomitant peripheral nerve involvement, but there has not been a case of LMC with isolated peripheral nerve findings to our knowledge. In this report, we present a case of LMC secondary to metastatic gastric adenocarcinoma in a patient whose only manifestation was cranial nerve palsies, and whose cancer was also found to be Her2+ and β-hCG positive, two markers not widely recognized in gastric cancer.