The 19-year-old had felt weak for several days. Then she took a single ibuprofen tablet and, within a short time, was struggling to breathe, vomiting repeatedly, and slipping into lethargy. Paramedics brought her to an emergency department in Rafsanjan, Iran, where staff initially suspected acute pulmonary edema.
Her oxygen saturation was 75%. Her heart was racing at 145 beats per minute. Her Glasgow Coma Scale score was 13, indicating impaired consciousness.
The actual cause, described on August 24 in the Journal of Medical Case Reports, was a parasitic cyst in her left lung roughly six inches long. The patient, an Afghan woman living in Iran, had no prior medical history at all.
The Water Lily on the CT Scan
Once she was stabilized, high-resolution CT imaging showed a large, thin-walled cyst in the left lower lobe measuring 150 by 93 millimeters, containing an air-fluid level. It had collapsed the upper portion of her left lung and pushed her heart, her mediastinum, and even her trachea toward the right side of her chest.
The scans also showed what radiologists call the water lily sign, the detached inner membrane of the cyst floating on the fluid inside it. It is a highly specific finding for hydatid disease.
Hydatid disease, also called cystic echinococcosis, is caused by the larval stage of the tapeworm Echinococcus granulosus. According to the Centers for Disease Control and Prevention, the parasite cycles between dogs, the definitive hosts, and livestock such as sheep, cattle, goats, and pigs. Most human infections cause no symptoms, while the cysts slowly enlarge in the liver, lungs, and other organs, sometimes going unnoticed for years. People pick it up by swallowing parasite eggs shed in the feces of infected dogs.
Surgeons opened her left chest through the fifth intercostal space and found the cyst occupying about 60% of the lower lobe. They aspirated its contents, removed the laminated membrane, and tied off the small airways it had opened into. Pathology confirmed the diagnosis by identifying the characteristic membranes and protoscolices, the immature tapeworm heads.
She was discharged on the fifth postoperative day with a three-month course of albendazole, an antiparasitic drug, and liver enzyme monitoring. At three months, she was asymptomatic. At six months, a chest X-ray and CT scan showed normal lung expansion and no recurrent cystic lesions, and she was released from surgical follow-up.
Why a Lung Cyst Affected Her Brain
The most striking detail is also the one that needs the most care in the telling: nothing invaded her brain.
Her altered mental status resolved within about an hour of supplemental oxygen once her low blood oxygen was corrected. A neurological examination found no focal deficits, no meningeal signs, and no seizure activity. Transient fainting, seizure disorder, and toxic ingestion were considered and ruled out.
The authors' interpretation is that the sheer volume of the cyst produced hypoxemia severe enough to impair brain function, a mechanism they call hypoxemia-induced encephalopathy. They present it as the explanation the evidence supports, not as a proven pathway, and they note that a brain CT was never performed because her consciousness recovered so quickly.
They are similarly cautious about the ibuprofen. The tablet preceded her collapse, and they speculate it may have triggered a mild allergic-type reaction or a transient rise in pressure inside the cyst, potentially causing partial rupture. The report labels this speculative and calls for further investigation. Readers should draw no conclusions about ibuprofen from a single unverified association.
Their literature search identified 15 published case reports of hydatid disease in migrant populations. None described altered mental status, which is what the authors present as this case's contribution.
Rare in the U.S., but Not Absent
For American readers, the relevant question is whether any of this touches them. Mostly, it does not.
Cystic echinococcosis clusters in regions with extensive livestock raising and close human-dog contact, including parts of Central Asia, the Middle East, the Mediterranean, East Africa, South America, and western China. Cases in the United States are uncommon and often occur in people who acquired the infection elsewhere. One of the 15 cases the authors reviewed involved a woman from Iraq treated in the United States, and another involved an 81-year-old man from Italy.
The CDC's clinical guidance notes that infection with E. granulosus is suggested by a cyst-like mass in someone with a history of exposure to sheepdogs in areas where the parasite circulates, and that antibody tests such as ELISA are highly sensitive for detecting it. The agency's prevention guidance centers on handwashing and avoiding contact with stray dogs in endemic regions.
The authors use their case to argue for screening migrants from high-prevalence regions with serology and chest imaging. They are explicit that a single case report cannot justify a policy change and that cost-effectiveness analyses and larger epidemiological studies would be needed first.
What the case does illustrate cleanly is a diagnostic trap. A young patient arriving with confusion and breathlessness invites a search for neurological or cardiac causes. Here, the answer was mechanical, sitting in plain view on a chest scan, inside an organ that nobody had yet imaged.
Key Questions Answered
What is a hydatid cyst?
It is a fluid-filled sac formed by the larval stage of the tapeworm Echinococcus granulosus after a person swallows parasite eggs. Cysts most often develop in the liver, followed by the lungs, and grow slowly over years.
How do people get infected?
By ingesting eggs shed in the feces of infected dogs, typically through contaminated food, water or soil, or through direct contact with an infected animal. People do not transmit it to one another.
Did the parasite reach her brain?
No. Doctors found no neurological deficits and identified no brain lesions. Her confusion resolved within about an hour once her oxygen levels were corrected, which is why the authors attribute it to severe hypoxemia rather than direct involvement of the brain.
Was the ibuprofen responsible?
Unproven. The authors note that the tablet preceded her collapse and offer possible mechanisms, but explicitly call the connection speculative and in need of further study.
How is hydatid disease treated?
Treatment depends on the size, location, and stage of the cyst. Options include the antiparasitic drug albendazole, image-guided percutaneous techniques, and surgery. This patient had surgical removal followed by three months of albendazole.
Is this a risk in the United States?
It is uncommon. The parasite is endemic in specific regions abroad, and U.S. cases tend to involve exposure elsewhere. Anyone with relevant travel or residence history and unexplained chest or abdominal symptoms should mention that history to a clinician.
