Investigation 007
What the Slide Cannot Say
Three parasites cause cancer. Nobody is checking for a fourth.
Cancer, found and missed
How cancer is tested
Six steps between the tumour and the diagnosis, and every one of them was designed to answer a different question than the one a parasite would raise.
What we are reading
Gathered for the investigation and not yet written up. Each note says what the paper does and does not show.
- Haghbin N, Oveisi B, Banitaba AP. Automated variable power cold microwave tissue processing: A novel universal tissue processing protocol without using formaldehyde and xylene.10.1016/j.acthis.2022.151880 · PMID 35344896
The cleanest plain statement of the pipeline every cancer diagnosis passes through: fixation, dehydration, clearing, paraffin infiltration, embedding, microtome slicing, staining, slide reading. Use their framing for the episode's spine, and note the two reagents they built the whole machine to avoid — formaldehyde and xylene — 'cause severe health and safety issues for humans and the environment'. The conventional protocol takes many hours; theirs takes 97 minutes. Tissue up to 4 mm thick.
- Roh CK, Jung MJ. Laparoscopic excision for ectopic peritoneal paragonimiasis mimicking a gastric duplication cyst: A case report.10.1016/j.amsu.2021.102754 · PMID 34484726
A 47-year-old man, no symptoms, an incidental peritoneal mass on a screening CT. Radiology called it a gastric duplication cyst. It was a lung fluke that had migrated out of the chest. The line to quote is the authors' own: 'the detection of the ova of Paragonimus parasites in sputum and BIOPSY SPECIMENS may be difficult due to an INSUFFICIENT AMOUNT.' Not because iodine destroyed it. Because there was not enough of it in the piece that was taken.
- Al Laham O, Abdul Khalek G, Alboushi H, Abazid E, Darwish A, Hamza A. An incidentally diagnosed primary pancreatic body hydatid cyst: A case report and literature review.10.1016/j.ijscr.2024.109392 · PMID 38367420
The mirror image of the episode's whole question. A 46-year-old woman with epigastric pain and a 'pancreatic body mass' on imaging went to theatre for what everybody expected to be pancreatic cancer — and lost her pancreatic body, tail and spleen. Histopathology found a hydatid cyst: a tapeworm larva. The parasite was only found BECAUSE the specimen was examined. That is the case for the pipeline, not against it, and an honest episode has to carry it.
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