Recurrent chest pain and palpitations unmasking a rare mediastinal arteriovenous malformation

A 35-year-old male with a history of pulmonary tuberculosis presented with recurrent episodes of left-sided chest pain, palpitations, and occasional fainting over 4 years. Physical examination, routine blood tests, and electrocardiogram were all unremarkable, as was a standard chest x-ray. However, a chest computed tomographty (CT) scan revealed a vascular malformation at the left anterior cardiophrenic angle, displaying a nidus fed by multiple systemic arteries, including the internal mammary, bronchial, diaphragmatic, and aortic arteries, as well as the lingular branch of the pulmonary artery, with probable drainage by the superior vein (Figs. 1 and 2). Due to the high risk of bleeding, a direct biopsy was avoided, and surgical intervention was elected after failed embolization attempts. Initial thoracoscopy under general anaesthesia revealed significant hypervascularization and adhesions, prompting a conversion to open mini-thoracotomy (Fig. 3a). Vascular control was achieved through the meticulous dissection and ligation of each feeding artery, allowing for complete resection of the vascular nidus surrounded by mediastinal fat, with no resection of the lung parenchyma. The postoperative course was uneventful. Microscopic examination revealed large tortuous thick walled arteries and veins, along with a small vessel component (Fig. 3b). The patient was discharged the day following surgery and remained asymptomatic throughout a three-year follow-up. Arteriovenous malformations (AVMs) have a prevalence of 1/100,000 individuals annually.1 Their occurrence in the mediastinum is extremely uncommon, corresponding to direct vascular communication between arteries and veins that bypass capillaries.2 Most AVMs are asymptomatic and are discovered incidentally on routine imaging, but their vascular nature raises the risk of bleeding during needle biopsy, making surgical resection preferred in symptomatic patients or when diagnostic confirmation is required.3 When symptomatic, mediastinal AVMs may present with chest pain, dyspnea, or high-output cardiac failure due to shunting. Larger lesions can lead to complications such as hemoptysis, compression of adjacent structures, or embolic events.4 Symptom severity often depends on the lesion's size and proximity to critical structures such as the pericardium or great vessels.5 In our case, it was located in the anterior mediastinum, on the pericardium, and close to the diaphragm, which possibly explains the patient's unusual chest symptoms. Given the patient's TB history, this AVM may have originated as a post-infectious sequela, though most mediastinal AVMs are congenital, linked to genetic syndromes like hereditary hemorrhagic telangiectasia (HHT), or acquired, often due to trauma.6 This emphasizes the need of evaluating infection-related vascular alterations, such as chronic inflammation and angiogenesis, when making a differential diagnosis of mediastinal tumours.5, 6 CT and MRI are valuable for detecting AVM connections to adjacent structures but may not always identify draining veins or provide detailed vascular mapping. In such cases, diagnostic needle biopsy poses risks.7 While embolization can reduce intraoperative bleeding,6, 8 its failure in this patient highlighted the significance of modifying surgical strategies, favouring open resection procedures in hypervascularized lesions. Surgeons should weigh the risks of intraoperative bleeding with thoracoscopic approaches, as open surgery may offer better control for managing hypervascular mediastinal lesions.9 Houssem Messaoudi: Conceptualization; writing – original draft. Habib Bessrour: Writing – original draft. Mokhles Lajmi: Investigation. Imen Ben Ismail: Data curation. Wafa Ragmoun: Data curation. Faten Gargouri: Supervision. Saber Hachicha: Validation. Written informed consent was obtained from the patient for the publication of this case report and the accompanying images.