Case report: inflammatory pseudotumor in the lung parenchyma caused by a medical suture originating from a cardiac surgery 35 years ago.

Background: The incidence of the iatrogenic foreign body retained after surgery is extremely low. Iatrogenic foreign body retained is surrounded by normal tissue, which responds to foreign matter to form inflammatory pseudotumors. Surgical sponge or swap is the most common type of foreign body. There were no reports of medical sutures remaining as foreign bodies in the lung parenchyma to form inflammatory pseudotumors.
Case Presentation: A CT scan of a 50-year-old female showed an irregular soft tissue mass in the left upper lobe with rough edge and spiculation. After 20 months, the size increased from 2.8 × 1.9 cm to 3.2 × 2.2 cm. The patient underwent a ventricular septal repair surgery for congenital Fallot tetralogy 35 years ago and a left breast surgery for breast cancer. She had a family history of lung cancer. Evaluation of this mass highly suggested a lung malignant lesion. The patient underwent video-assisted thoracoscopic surgery (VATS) lobectomy and her pathology revealed an intrapulmonary inflammatory pseudotumor caused by a medical prolene suture. Based on her medical history and other reports of iatrogenic foreign bodies, we believe that this suture retained from the heart surgery 35 years ago entered the pulmonary artery, moved to the distal branch, and eventually formed an inflammatory pseudotumor in the lung parenchyma. Here we reported and analyze this rare case.
Conclusion: We reported a rare case of inflammatory pseudotumor in the lung parenchyma caused by a medical suture, and determined it was a prolene suture retained in the body during a cardiac surgery 35 years ago. Diagnosis of this rare disease required sufficient imaging experience. Besides, appropriate surgical exploration can help with the diagnosis and treatment.