Diagnosis of Suspected Brain Tumor Turns Out to Be Parasitic Infection: Case Report

A 60-year-old man residing in Spain sought medical attention after experiencing worsening headaches and subtle behavioral changes over a two-week period. Neurological examinations revealed mild motor delays, but no other significant deficits were observed. Blood tests showed elevated IgE levels, suggesting an immune response associated with allergies, autoimmune diseases, or parasitic infections. Physicians conducted a CT scan of the patient’s brain, which revealed multiple lesions and associated edema throughout the brain.

This case was reported in the academic journal Emerging Infectious Diseases. Despite the absence of immunodeficiency or international travel history, the medical team initially suspected a metastatic brain tumor as the most likely diagnosis.

The Diagnostic Process and a Turning Point

Anti-inflammatory corticosteroids were administered to alleviate the patient’s headaches, leading to temporary symptom improvement. To investigate potential metastasis, comprehensive tests, including full-body contrast-enhanced CT, colonoscopy, and PET/CT scans, were performed. However, no malignant tumors were detected through these examinations.

Confirmation via MRI

A subsequent, more detailed MRI scan provided a definitive diagnosis. The imaging revealed that the lesions were not tumors but encapsulated larvae of the tapeworm Taenia solium. The scolex, or head, of the parasite was clearly visible in the MRI images, confirming the presence of neurocysticercosis.

Tracing the Infection Route

What surprised the medical team was the fact that Taenia solium is not endemic to Spain, and the patient had no history of international travel. The suspected infection route was linked to the patient’s occupation as a construction worker before his retirement a decade earlier. During this time, he worked alongside laborers who had migrated from regions where the parasite is endemic. It is hypothesized that rare fecal-oral transmission occurred through shared meals or sanitation facilities at the workplace.

Infection Mechanisms of Taenia solium

Taenia solium can infect humans via two primary routes. One involves consuming undercooked pork containing cysticerci (larval cysts), while the other involves ingesting eggs from fecal contamination. When pigs consume feces containing tapeworm eggs, the larvae hatch in the intestines, penetrate the intestinal wall, and enter the bloodstream. They then migrate to various tissues and muscles, where they form encapsulated cysts. Humans who eat raw or inadequately cooked pork containing these cysts may develop adult tapeworms in their intestines, which can survive for extended periods.

Editorial Opinion

This case highlights the potential for misdiagnosis, even with advances in imaging technologies, as metastatic tumors were initially considered the most likely explanation. Without detailed MRI analysis, the patient might have undergone unnecessary biopsies or cancer treatments. In the short term, this underscores the importance of considering parasitic infections in the differential diagnoses of brain lesions.

From a long-term perspective, artificial intelligence could play a pivotal role in assisting with pattern recognition in diagnostic imaging. Differentiating between tumors and cystic lesions presents a valuable challenge for training supervised learning models. Additionally, the increased prevalence of parasitic infections in non-endemic regions due to international labor migration may prompt a reevaluation of public health risk assessment methods.

Infection risk assessments in workplace environments remain an underdeveloped area. Corporate health management teams may need to consider not only employees’ travel and work histories but also indirect exposure pathways. This is a topic that warrants further debate and exploration.

References

• Doctors suspected man had brain cancer. He actually had worms. | Ars Technica — Published June 26, 2026