Bilateral Aseptic Cavitary Lung Lesions in Chronic Thromboembolic Pulmonary Hypertension: A Rare Association

Sir, Chronic thromboembolic pulmonary hypertension (CTEPH) is a subtype of pulmonary hypertension (PH) arising due to mechanical obstruction of vessels by organized thrombus. It is one of the rare causes of PH which can be completely managed by surgical intervention. CTEPH has a wide range of radiological presentations, including peripheral obstructions visualized as filling defects, dilated main pulmonary arteries, and mosaic attenuation. Although rare, cavitary lung lesions have been reported to be associated with CTEPH.[1,2] We herein report a case of bilateral aseptic lung cavities caused by chronic pulmonary thromboembolism. A 37-year-old female presented to our institution with complaints of persistent productive cough, progressively worsening exertional dyspnea corresponding to modified Medical Research Council grade III, and bilateral lower limb swelling for the last 1 year. The patient gave a history of being diagnosed with unprovoked acute pulmonary embolism 1 year ago, which was managed with anticoagulation therapy for 6 months. Post 6 months of therapy, two-dimensional (2D) echo showed mild PH, and computed tomography pulmonary angiography (CTPA) revealed features of chronic pulmonary embolism with normal pulmonary parenchyma (as per the patient’s medical records, images not available). In view of CTEPH, the patient was continued on anticoagulant therapy. During the ensuring 6 months, the patient gave a history of lower respiratory tract infections which were managed on an outpatient basis at a peripheral hospital with oral antibiotics. Clinical examination revealed elevated jugular venous pressure, cavernous breath sounds over the right infra-axillary region, and increased vesicular breath sounds over the left lung fields. Cardiac auscultation was notable for a loud second heart sound with no added murmurs. Suspecting acute-on-chronic pulmonary embolism, CTPA was taken, which revealed features of chronic pulmonary embolism in the right main pulmonary artery along with multiple thick-walled cavitary lesions in the right lung parenchyma [Figure 1a and b]. 2D echo demonstrated moderate PH, and spirometry showed moderate obstruction. Microbiological evaluation, including sputum Gram stain, Ziehl–Neelsen staining, fungal culture, and GeneXpert testing for Mycobacterium tuberculosis and polymerase chain reaction for nontuberculosis mycobacteria, was negative. Bronchoalveolar lavage tested positive on BioFire® pneumonia panel for human rhinovirus and enterovirus but was negative for bacterial and fungal pathogens. An autoimmune, vasculitis, and thrombophilia workup was conducted, all of which were negative. Human immunodeficiency virus, hepatitis B, and hepatitis C serologies were also negative. Doppler ultrasound of the bilateral lower limbs showed no evidence of deep vein thrombosis.Figure 1: (a) Computed tomography pulmonary angiography demonstrating an irregular filling defect (red arrow) , measuring approximately 44 mm×20 mm size causing near total obliteration of the right branch of the pulmonary artery. The filling defect extends up to the lower and upper lobar branches. (b) Multiple patchy air space opacities and cavities are seen at the right upper, lower, and middle lobes, along with early bronchiectasis changesIn light of the clinical course, radiographic findings, and exclusion of other causes, a diagnosis of CTEPH with secondary cavitary lung lesions was established. The patient was advised pulmonary endarterectomy but did not consent to the procedure. She was managed with continued anticoagulation therapy, inhaled bronchodilators, and oral riociguat, with which she reported improvement in her symptoms. Cavity formation in the lungs is classically associated with infectious diseases, particularly tuberculosis, necrotizing bacterial pneumonia, and fungal infections.[3] Although rare, noninfectious etiologies such as malignancy, autoimmune disease, and vascular disorders like CTEPH must also be considered, especially when there is no evidence of any infection. Studies have shown that cavity formation occurs in up to 5% of patients with CTEPH and is significantly more frequent than in acute pulmonary embolism.[4] The pathophysiological mechanisms include ischemic lung injury, superimposed infection, and, in some cases, immune-mediated vascular inflammation. As the lung has a dual blood supply, obstruction of the pulmonary vascular supply alone will be insufficient to cause ischemic necrosis, but the additional perfusion burden imposed by super-added infections can lead to necrosis and subsequent cavity formation. These infections may resolve leaving behind cavities which fails to heal due to poor perfusion. Treatment options for CTEPH include pulmonary endarterectomy, the definitive therapy for operable cases, with perioperative mortality rates of <5% at experienced centers. For patients deemed inoperable due to distal disease or comorbidities, medical therapy with pulmonary vasodilators such as riociguat may provide symptomatic benefit.[5] There are no therapies specific to cavitary lung disease caused by CTEPH. Sensitization of clinicians regarding the potential of cavity formation when CTEPH is associated with lung infections may facilitate early and appropriate treatment of these infections, thus potentially preventing long-term sequelae. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.