A 29-year-old female presented with new onset generalized tonic-clonic seizure. She described a three year history of intermittent bilateral temporal headaches. Past medical history was remarkable only for prior injection drug use, from which she had been abstinent for three years. Her only medication was daily buprenorphine-naloxone. She was born and raised in rural Vermont, and had never travelled outside the state. She worked in a manufacturing facility where she often shared lunch prepared by co-workers, many of whom had recently emigrated from South Asia. She was a 15 pack-year smoker and drank minimal alcohol. She had one cat who was treated for an intestinal worm infection two years prior. The family history was notable for breast cancer in her maternal aunt at age 40.
Upon presentation for care after the seizure, the patient was afebrile with normal vital signs. Aside from an initial post-ictal state, physical and neurologic examinations were unremarkable. Initial laboratory results showed a white blood cell count of 7.2 x 103 cells/muL, hemoglobin of 13.3 g/dL, platelets of 270 x 103/muL, and serum creatinine of 0.6 mg/dL. A computed tomography (CT) scan of the brain was notable for numerous cystic lesions. A subsequent magnetic resonance imaging (MRI) study of the brain with gadolinium contrast showed approximately 35 smoothly circumscribed cystic structures throughout the supra- and infra-tentorial brain parenchyma (Fig. 1). The cystic lesions ranged in size from 2 to 33 mm, the largest located in the left temporal lobe. Notably, mass effect, perilesional edema, and restricted diffusion were absent on MRI. A lumbar puncture was performed and cerebrospinal fluid (CSF) analysis demonstrated no white blood cells, normal glucose and protein, and negative bacterial, fungal, and mycobacterial stains and cultures. Chest X-ray was normal.
The initial working diagnosis was neurocysticercosis, with consideration given to tuberculosis, toxoplasmosis, cryptococcus, histoplasmosis, blastomycosis, echinococcus, nocardia, and malignancy. Negative results included cysticercosis serum and CSF IgG enzyme-linked immunosorbent assay (ELISA), interferon gamma release assay for tuberculosis, toxoplasma CSF polymerase chain reaction and serum IgG serology, CSF cryptococcal antigen, urine histoplasma and blastomyces antigens, serum echinococcus serology, and fourth generation human immunodeficiency virus assay. No empiric antimicrobial agent was given.
Repeat MRI four weeks later showed a slight increase in the size of the cystic lesions, up to 35 mm. Six weeks after initial presentation, a brain biopsy of the left posterotemporal cystic lesion was performed, with pathology demonstrating metastatic neuroendocrine tumor (Fig. 2). A CT chest then showed a 3 cm irregular mass in the lower lobe of the left lung, not seen on the prior chest X-ray. A positron emission tomography scan showed fluoro-deoxy-glucose uptake in the lung lesion, the cystic brain lesions, and the T8 vertebral body. She was diagnosed with lung neuroendocrine tumor with cystic brain metastases, and treated with carboplatin, pemetrexed, and pembrolizumab. Subsequent imaging has shown a decrease in lesion size and no further metastases.