Here's a chest X-ray that made the radiologist gasp and reach for the phone. What could this thin grey line possibly be? The patient was a 30 yo male, no significant medical history, who had started to experience stabbing pains in his chest a few days earlier.

A CT gives a clearer view of something definitely abnormal. The patient, who worked in a sofa factory, "firmly excluded recent trauma or accidental
injuries", though doctors noticed a small puncture injury on the left chest wall.

A planned echocardiogram was abandoned when he started to sweat violently, his blood pressure dropped and his jugulars became distended. Cardiac tamponade, you cry! And so he was whisked into surgery, where a large excoriation was found in the wall of the left ventricle.

450 ml of blood had escaped into the pericardium, causing the tamponade. The culprit: a 5 cm sewing needle! The patient later admitted it had penetrated his chest accidentally - as he was working illegally he was reluctant to reveal what had happened. He made a good recovery.

Historical footnote: this case is strikingly similar to one from 1872. A London surgeon called George Callender removed this sewing needle from the heart muscle of a young man - the first time on record that a foreign body was removed from the myocardium of a living patient.

The needle is still in the collections of Barts Pathology Museum @BHAandM. The inscription, written shortly after the operation, reads: "“Needle removed from heart nine days after its insertion. Length 1.9 inches. The patient recovered."

The case report at the top of this thread, incidentally, can be read here: https://journals.lww.com/jcardiovascularmedicine/Abstract/2016/12002/Cardiac_tamponade_caused_by_a_migrating_sewing.12.aspx