Diagnostic dilemma: A knife broke off in a man's chest, and he didn't notice it for 8 years

The patient: A 44-year-old man in Tanzania

The symptoms: For 10 days, pus oozed from an opening in the man's chest below his right nipple, prompting him to visit the emergency room. He told doctors he had no pain or difficulty breathing. He did not have a fever, and his vital signs were normal.

What happened next: When the doctors examined the man, they found that his rib cage on the right side of his chest was flattened at the front and that his chest did not fully expand on that side when he inhaled. They confirmed that "foul-smelling" pus was leaking from a cavity under the nipple, they wrote in a report of the case.

During the examination, the man reported that, eight years earlier, he had been stabbed repeatedly in the chest, back, abdomen and face during a "violent altercation." No imaging tests were performed at that time, and he received only superficial first-aid treatment for the multiple knife wounds. For eight years, he had no health issues resulting from those injuries, he said.

The diagnosis: An X-ray revealed a large metallic knife blade lodged inside the man's thoracic cavity. Also known as the chest cavity, this hollow chamber is located above the abdomen and contains the heart and lungs. The blade, which extended from the rear of the rib cage to the front, had entered the man's back near his right scapula, or shoulder blade.

The knife's blade slid between the fifth and sixth ribs in the patient's back and then stuck there, with the knife's tip positioned between the third and fourth ribs at the front of his rib cage. A CT scan showed healed fractures in his scapula and in several ribs. Layers of pus and dead or dying tissue surrounded the knife blade.

One way the body protects itself against foreign objects is through a process called fibrous capsule formation, in which the immune system cocoons the object in collagen and other fibers to limit damage and inflammation in the surrounding tissue. Such encapsulation of the knife is likely what enabled the man to spend the next eight years unaware that there was a blade inside his chest, according to the report.

The treatment: Surgeons at the hospital performed a thoracotomy, in which they cut into the man's chest wall to remove the blade. They drained the accumulated pus, flushed the chest cavity with a solution of sodium chloride, installed a drainage tube and finally sutured the wound. The patient received broad-spectrum antibiotics for seven days and was closely monitored for signs of infection following the surgery.

Doctors removed the drainage tube after the eighth day, and the man was discharged two days later. He returned to the hospital for two follow-up appointments: one two weeks after his surgery, and one six weeks afterward. At both visits, he was infection-free and experienced no further complications.

What makes the case unique: After a traumatic chest injury, it's not unusual for part or all of the penetrating object to be left behind in the chest cavity. However, most of the time, these foreign bodies are small ballistic projectiles, such as bullets, which are often difficult to locate and remove.

By comparison, large shards — for example, entire knife blades or other stabbing weapons — that break off and become lodged in the chest are less commonly documented in the medical literature. And in most cases, these objects do not go undetected for years; they are typically identified and removed within weeks or months, according to the report.