¹⁸F-labeled fluoro-2-deoxyglucose positron emission tomography-computed tomography scan findings in anaplastic lymphoma kinase-positive carcinoma lung: Institutional experience

Lung cancer is the most common cancer worldwide and leading cause of cancer mortality. Recently, many targeted therapies such as epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) mutations are being used with gratifying results. Our objective was to evaluate findings in ALK-positive carcinoma lung in staging ¹⁸F-labeled fluoro-2-deoxyglucose positron emission tomography-computed tomography (¹⁸FDG PET/CT) scan. Among patients referred for staging PET/CT scans between 2015 and 2017, 400 of them underwent ALK mutation testing. 18 patients were ALK positive. Images are reviewed; SUVmax value and CT finding of primary mass, regional nodal status, and distant metastases are evaluated and analyzed. Primary mass was centrally located in 17 cases (94.4%), solid in nature in all cases, smooth and lobulated margins in 13 cases (72.2%), pleural retraction in three cases (15.8%), and airbronchograms in one case (5.3%). Median size of the mass was 2.95 cm (interquartile range 2.59–4.18). Median SUVmax value was 12.85 (interquartile range 11.00–15.2). Fifteen cases (83.3%) had distant nodes, one case had only ipsilateral hilar nodes, one case had ipsilateral hilar and mediastinal nodes, and one case had bilateral hilar and mediastinal nodes. Most of the cases had perinodal spread. All cases have distant metastases. Distant spread includes lung metastases (seven cases), lymphangitis carcinomatosis of lung (two cases), liver (seven cases), adrenals (five cases), bones (six cases), pleura (two cases), brain (one case), soft tissue (one case), and distant lymph nodes. Characteristic features of ALK-positive carcinoma lung in staging ¹⁸FDG PET/CT scan include centrally located solid mass with smooth and lobulated margin, median size of 2.95 cm, and median SUVmax value of 12.85. Majority of the tumors had distant nodes, and all had distant metastases