Our 10 oddest medical case stories from 2023

close up on legs of medic wearing scrubs and walking with a gurney along hospital corridor.
Some medical cases are so bizarre that they bewilder even doctors. (Image credit: Phil Fisk via Getty Images)

Doctors can see thousands of patients a year, and sometimes, they encounter cases that completely flabbergast them or else turn out to be incredibly rare. When this happens, they'll often chronicle the cases in medical journals so that clinicians and members of the public alike can learn about the intriguing complexities of the human body, as well as keep an eye out for these often lesser-known conditions.

Here are some of the oddest medical cases that we covered in 2023.

Related: 10 bizarre medical case reports from 2022

1. Scuba dive triggers deadly blood syndrome

After scuba diving deep into an underwater cave, a man developed a deadly blood syndrome that caused fluid to leak out of his blood vessels. Doctors quickly recognized that the man had an extremely rare complication of decompression sickness, known as systemic capillary leak syndrome, and were able to give him prompt, life-saving treatment.

2. Rustling spider found in woman's ear

Close-up view of the tiny spider crawling in the woman's ear, with its discarded exoskeleton next to it

Here's the spider that was living in the woman's left ear canal, next to its exoskeleton. (Image credit: The New England Journal of Medicine ©2023.)

A woman in Taiwan got a nasty surprise when doctors discovered a 0.1-inch-long (0.25 centimeter) spider crawling in her left ear, alongside its hard, molted outer shell. For four days, she'd been hearing weird clicking and rustling noises coming from her ear — but she probably didn't suspect a hairy arachnid would be responsible for the disturbing sounds.

3. Man's tongue sprouts thick, green 'fur'

A moss-like growth developed on a man's tongue. The condition, appropriately known as hairy tongue, is caused by an overgrowth of the bumps on the tongue that are normally shed when they come into contact with rough objects, such as a toothbrush or solid, textured foods. About 13% of people experience hairy tongue at some point in their lives, and the hairs can be any color, depending on the types of food and bacteria that get trapped in them.

4. New species of bacteria identified after stray cat bite

Scientists discovered a new species of bacteria after a man was bitten multiple times by a stray cat. His hands and forearms turned red and swelled up, but the man fully recovered after a five-day course of antibiotics. In the lab, scientists determined that he'd been infected by a type of Globicatella bacteria, a small microbe that resembles Streptoccocus bacteria, best known for causing strep throat and scarlet fever.

 5. Fetus removed from 1-year-old's brain

Doctors surgically removed a fetus from a 1-year-old's brain in an extremely rare medical case. The fetus was the child's monochorionic diamniotic twin, meaning it had come from the same fertilized egg as the child and also shared the same placenta, but it had developed in a separate amniotic sac. During pregnancy, one fetus was enveloped by the other and died as a result, but its remnants remained in the remaining child's head even after birth.

6. Knife blade 'floats' to other side of man's belly

X-ray of the knife blade stuck in the man's abdomen

An X-ray revealed that the blade had moved from the right to the left side of a man's belly after he was stabbed.  (Image credit: Nepal, A, Rajbhandari A P., et al. (2023). doi:10.7759/cureus.44575 (https://creativecommons.org/licenses/by/4.0/))

Doctors stitched up a man's knife stab wound but forgot one important thing: the 5.9-inch (15 cm) blade was still stuck in his belly. A day later the blade had "wandered" to the other side of the man's body, but miraculously, it did so without damaging any of his surrounding organs.

7. Python parasite invades woman's brain

A woman in Australia was infected with a parasitic worm called Ophidascaris robertsi that normally lives in pythons and has never been known to infect humans before. Doctors pulled the 3.15-inch-long (8 cm) red worm, which was still alive and wriggling, out of her brain. It's thought that the woman accidentally consumed O. robertsi eggs either from directly eating contaminated leafy greens or indirectly via her soiled hands or kitchen equipment.

8. Toddler's brown eyes turned blue after taking COVID-19 drug

After taking an antiviral drug called favipiravir to treat COVID-19, a 6-month-old boy's dark-brown eyes suddenly turned indigo blue. This shocking color change was believed to be a side effect of how the body processes the drug. The boy's eyes returned to their usual color after treatment was stopped. However, doctors said the potential long-term effects tied to this temporary change in eye color are still unknown.

9. Tooth extraction causes man's brain to bleed 

A man's trip to the dentist had to be followed by a visit to the emergency department after a tooth extraction indirectly triggered bleeding in his brain. Doctors theorize the bleeding was caused by a sudden increase in blood pressure after the man's procedure. In addition, the patient had an undiagnosed genetic condition that reduces the flow of blood through the brain, which could have contributed.

10. Painful rash from eating undercooked mushrooms

A man developed a painful, itchy rash all over his back after eating undercooked shiitake mushrooms. The rash, which appeared streaky and red as if the man had been whipped, was caused by an overblown inflammatory reaction to a carbohydrate called lentinan. The carb is normally broken down at high temperatures during cooking, but raw and undercooked shiitake mushrooms contain enough to trigger a reaction.

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Emily Cooke
Staff Writer

Emily is a health news writer based in London, United Kingdom. She holds a bachelor's degree in biology from Durham University and a master's degree in clinical and therapeutic neuroscience from Oxford University. She has worked in science communication, medical writing and as a local news reporter while undertaking journalism training. In 2018, she was named one of MHP Communications' 30 journalists to watch under 30. (emily.cooke@futurenet.com