A 60-year-old man in Castellón, Spain, presented with two weeks of progressive headaches and mild behavioral changes; CT scans showed multiple lesions so closely resembling metastatic tumors that physicians suspected advanced cancer. Exhaustive oncology testing found no malignancy anywhere in his body, and a detailed MRI followed by blood work confirmed neurocysticercosis — a parasitic infection of the central nervous system caused by the pork tapeworm Taenia solium. The case, published in the CDC journal Emerging Infectious Diseases, makes a pointed argument for clinicians in non-endemic countries: a brain lesion that looks like cancer is not always cancer.
A Diagnosis Nobody Expected in a Man Who Had Never Left Spain
The patient was a lifelong resident of Castellón with no history of travel to any region where neurocysticercosis is endemic. The initial CT imaging showed multiple ring-enhancing lesions — a pattern that, in a Western European clinical setting, points strongly toward metastatic disease. Whole-body scans, a colonoscopy, and specialized imaging were ordered; all returned negative for malignancy. Only a higher-resolution MRI revealed the true picture: fluid-filled cysts in the brain, several containing what imaging identified as the head of a tapeworm.
How Tapeworm Eggs Reach the Brain Without a History of Eating Contaminated Pork
The transmission route matters because it explains how someone develops brain cysts without ever consuming undercooked infected meat. Eating contaminated pork typically produces an intestinal tapeworm, confined to the gut. The more serious pathway involves accidentally ingesting tapeworm eggs — usually through food or water contaminated with fecal matter — which allows larvae to migrate through the bloodstream and form cysts in the brain and other organs.
The case authors suggested the patient may have been exposed years earlier while working in construction alongside migrant coworkers from regions where the disease is endemic. That specific pathway could not be proven from a single case, and the researchers were careful to note that the findings cannot be generalized to a broader population.
Treated Successfully, Though the Diagnostic Gap Carried Real Risk
The patient was treated with albendazole and praziquantel, two antiparasitic medications, combined with corticosteroids to reduce brain inflammation. He recovered fully with no complications. The authors noted that an earlier diagnosis could have prevented unnecessary invasive oncology procedures and allowed antiparasitic therapy to begin sooner — a meaningful distinction given that neurocysticercosis can, in some cases, produce seizures, stroke, neurological deficits, and cognitive decline.
The rarity of locally acquired cases makes the diagnostic leap genuinely difficult. A prior systematic review identified only 18 confirmed locally acquired cases across Western Europe between 1990 and 2011. In the United States, fewer than 2% of neurocysticercosis diagnoses are considered domestically acquired.
The researchers' conclusion is direct: the absence of travel history should not remove neurocysticercosis from the differential diagnosis of multiple ring-enhancing brain lesions, even where metastatic cancer is statistically far more probable. One case cannot determine how frequently local transmission occurs in non-endemic settings. What it does establish, unambiguously, is that it can.