A cautionary case of a 60-year-old woman who coughed blood for four months underwent surgery and was found to have a lung fluke hidden in her lung, initially mistaken for cancer, after eating “raw soy sauce-marinated crab” with prevention advice provided
On 25 June 2026, a report stated that the Facebook pageFMC Medical Clinicposted educational information about a woman who had to undergo surgery due to eating raw soy sauce-marinated crab.
The post stated: “Raw soy sauce-marinated crab leads to surgery! A lung fluke hidden in the lung was mistaken for cancer.” It told the story of a 60-year-old woman with chronic coughing and coughing up blood for four months. An X-ray showed a lung mass resembling cancer.
However, after surgery, a “pre-adult stage lung fluke” was found hidden within the lung lesion, traced to eating “Gejang” or raw freshwater crab marinated in soy sauce, a popular Korean dish.
The lung fluke (Paragonimus westermani) is a parasite transmitted to humans by eating raw or undercooked freshwater crab, shrimp contaminated with the metacercaria larval stage, and some wild meats such as wild boar and deer, which act as paratenic hosts.
A case report described a 60-year-old Korean woman with prolonged coughing with sputum and coughing up blood, along with elevated blood eosinophils. A CT scan revealed a 2.8 cm mass in the right lung resembling lung cancer, leading to lobectomy surgery.
Pathological examination found a necrotizing granuloma lesion with central tissue death and a 5-millimeter pre-adult lung fluke larva inside the lesion cavity. No parasite eggs were found in the tissue, explaining why pre-surgery sputum tests were negative.
Genetic analysis (ITS2 sequencing) confirmed Paragonimus westermani, a species common in Korea, Japan, and China.
After surgery, further history revealed the patient had eaten “Gejang” or raw soy sauce-marinated freshwater crab about three months before symptoms began, identified as the likely infection source.
Following a three-day course of the antiparasitic drug Praziquantel, blood eosinophil levels returned to normal.
This case highlights that lung fluke infection can mimic lung cancer, and diagnosis is difficult in the egg-laying pre-adult stage without detailed dietary history of raw food consumption.
Though lung lesions from P. westermani resemble tuberculosis or lung cancer, the true cause may be a small “secret passenger” from a single raw meal, hiding in the lung for months before detection.
Recommendations for prevention