Pulmonary Hypertension with a Classical Sign on Computed Tomography Scan

Clinical Summary A 55-year-old female, current smoker with a two-decade history of past smoking, presented with gradually worsening breathlessness accompanied by visible jugular venous distension and bilateral pedal edema. Despite conventional medical therapy with inhaled triple drug combination and oral xanthine derivative regularly, her symptoms remain unresolved, prompting further evaluation with computed tomographic (CT) scan chest and echocardiography. Investigations Her chest radiograph posteroanterior view showed cardiomegaly with bilateral hilar prominence and bilateral mid to lower zone prominent bronchovascular markings. The right-sided costophrenic angle was also obliterated [Figure 1].Figure 1: Chest X-ray showing cardiomegaly with bilateral hilar prominence and mid to lower zone prominent bronchovascular markings apart from right side costophrenic angle bluntingHer echocardiographic evaluation disclosed enlarged right atrium and right ventricle, moderate tricuspid regurgitation with right ventricular systolic pressure = right atrial pressure + 40 mm Hg. Contrast CT scan chest revealed a main pulmonary artery (MPA) measurement of 41 mm, with the corresponding aorta measuring 27 mm, reflecting a pulmonary artery (PA) to aorta ratio >1. Other findings were the left MPA measuring 27 mm, right MPA measuring 28 mm, suggestive of pulmonary hypertension. Cardiothoracic ratio measured around 69% suggestive to have cardiomegaly [Figure 2a and b].Figure 2: (a) Contrast CT chest showing main pulmonary artery (MPA) measures 41 mm, corresponding aorta measures 27 mm with pulmonary artery to aorta ratio of >1. Left MPA measures 27 mm, right MPA measures 28 mm. (b) Classical radiological signQuestions Question 1 What is the characteristic radiological sign evident on CT images? Question 2 Briefly describe this radiological sign. Answers Answer 1 Egg-and-banana sign. [Figure 2b showing egg representing dilated MPA trunk and banana representing aortic arch at the same level]. Answer 2 Pulmonary arterial hypertension (PAH) is a progressive condition characterized by elevated PA pressures, ultimately leading to right heart failure if left untreated. Early diagnosis is crucial for effective management and improved patient outcomes. The “egg-and-banana” sign, identified on contrast-enhanced chest computed tomographic (CT), has emerged as a specific and valuable radiological marker for PAH.[1] The “egg-and-banana sign” manifests when the MPA becomes significantly dilated and lies lateral to the aortic arch. On axial CT images, this forms a configuration resembling an “egg” (MPA) beside a “banana” (aortic arch). This MPA enlargement is due to increased pulmonary vascular resistance, resulting in structural changes such as smooth muscle hypertrophy and intimal fibrosis, a hallmark of advanced PAH.[2] The “egg-and-banana” sign has been correlated with elevated mean PA pressures, providing a noninvasive clue to the diagnosis of PAH. In a study involving 186 patients, the presence of the sign was significantly associated with larger MPA diameters and increased PA-to-aorta ratios.[3] When this sign is observed alongside other findings, such as an MPA diameter >29 mm and a PA-to-aorta ratio >1.0, the diagnostic sensitivity and specificity for PAH increase substantially.[4] The “egg-and-banana” sign may not be observed in all cases of PAH with PA trunk diameter more than that of the ascending aorta. It is defined as a visualization of the lumen of the MPA at the caudal aspect of the highest portion of the aortic arch in at least one axial slice.[1] Identification of the “egg-and-banana” sign on CT scans should prompt further evaluation for PAH, particularly in patients with persistent or worsening symptoms like unexplained dyspnoea or fatigue.[1] This sign is a distinctive and specific radiological indicator of PAH. Its presence can lead to early referral for confirmatory right heart catheterization and timely initiation of therapy. Its detection can enhance early diagnosis, guiding appropriate management and potentially improving long-term outcomes.[4] 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.