How is Eurytrema pancreaticum diagnosed in humans and what diagnostic pitfalls cause misidentification?
Executive summary
Human infection with the pancreatic fluke Eurytrema pancreaticum is diagnosed primarily by direct detection—visualizing adult worms at autopsy or on endoscopic imaging, identifying characteristic eggs or adult morphology in tissue or feces, and increasingly by molecular methods to separate closely related species—yet cases are rare, often incidental, and prone to misidentification because eggs mimic other trematodes, routine stool tests can be falsely negative, and imaging can mimic pancreatic tumors [1] [2] [3] [4] [5].
1. How confirmed diagnoses are made: pathology, imaging and parasitology
Definitive diagnosis has historically depended on finding adult flukes in the pancreatic ducts at autopsy or following endoscopic retrograde pancreatography (ERCP), with morphological descriptions—size, body shape and sucker dimensions—used to identify E. pancreaticum (examples from an autopsy series and classic descriptions) [1] [6]; modern clinical reporting also documents imaging evidence of pancreatic eurytremiasis in living patients where obstructive jaundice or a suspected pancreatic mass led to imaging and intervention that revealed parasites [2].
2. Eggs, stool exams and the problem of sensitivity
Routine coproparasitological (stool) testing can detect trematode eggs and has produced incidental human findings, but multiple sources warn that routine fecal exams commonly give false negatives for Eurytrema spp., raising the chance of missed infections in humans and animals when eggs are absent or scant in samples [3]. The eggs’ reported dimensions and morphology are documented in case reports, which is why lab diagnosis still relies on microscopy when material is available [1].
3. Molecular and phylogenetic confirmation: resolving look‑alikes
When morphology alone is ambiguous, molecular tools—PCR and sequence analysis—can distinguish E. pancreaticum from related Eurytrema species (and from other trematodes) because phylogenetic analyses of ribosomal genes and ITS regions form species‑specific clades; veterinary studies applying PCR demonstrated clear separation between E. pancreaticum and E. coelomaticum, a distinction that matters when eggs look nearly identical [4].
4. Imaging pitfalls: parasites masquerading as tumors or biliary disease
Clinical imaging can mislead: the single comprehensive imaging report showed a patient referred for obstructive jaundice and a presumed pancreatic tumor where imaging and subsequent procedures revealed pancreatic eurytremiasis, illustrating how parasites in pancreatic or biliary ducts may present like neoplasia or cholestatic disease [2]. The uncommon location of E. pancreaticum relative to other trematodes—its normal habitat being the pancreas rather than the bile duct—adds another layer of diagnostic confusion when radiologic signs are interpreted without parasitology correlation [5].
5. Egg similarity and laboratory misidentification
A central laboratory pitfall is egg similarity: Eurytrema eggs can resemble those of other zoonotic trematodes, and authoritative diagnostic resources note that eggs may be “nearly identical,” which can produce acceptable but non‑specific identifications unless the clinical context or molecular testing clarifies the species [5] [4]. In practice this means labs must combine egg morphology, host/site information and, where possible, molecular sequencing to avoid misclassification.
6. Rarity, incidental findings and the risk of over‑ or under‑diagnosis
Human eurytremiasis is rare and often incidental—found at autopsy or during unrelated exams—so clinicians and pathologists may not consider it, producing under‑diagnosis; conversely, social media and some fringe claims have promoted unfounded links between Eurytrema and common diseases like diabetes, a narrative debunked by fact‑checking and not supported by clinical literature, which risks causing over‑interpretation of ambiguous findings [3] [7].
7. Practical takeaways for accurate identification
Accurate diagnosis requires integration: consider Eurytrema when pancreatic duct lesions, obstructive jaundice or unusual eggs are present; confirm with morphology on recovered adults or eggs, use molecular tests to resolve species-level ambiguity, and be aware that stool tests often miss infections and that imaging can mimic tumors—laboratory and clinical teams should therefore communicate and, where uncertainty persists, pursue targeted molecular or histopathologic workup [1] [2] [3] [4] [5].