CLINICAL VIGNETTES 199 www.journals.viamedica.pl Address for correspondence: Prasanta Raghab Mohapatra, Department of Pulmonary Medicine, AIIMS, Bhubaneswar, Odisha, India 751019; e-mail: prmohapatra@hotma- il.com DOI: 10.5603/ARM.2019.0032 Received: 25.04.2019 Copyright © 2019 PTChP ISSN 2451–4934 Confict of interest: none declared Cystic transformation of cannon ball metastases in response to EGFR TKI Satyajeet Sahoo, Prasanta Raghab Mohapatra, Saroj Kumar Das Majumdar, Mantyu Chhatria All India Institute of Medical Sciences, Bhubaneswar, India A 39-year-old never smoker male with a 3-month history of progressive dyspnea was found to have a heterogeneously enhancing right lung mass with multiple, well circumscribed rounded lesions of varying sizes, ranging from nodules to masses in both lungs, suggestive of cannon ball lesions [Figure 1 A–C]. Bron- choscopic biopsy revealed adenocarcinoma of the lung diffusely positive to thyroid transcription factor 1 (TTF1) and napsin. Contrast-enhanced computed tomography (CECT) scan of the abdomen and pelvis ruled out the presence of any synchronous tumor elsewhere. Epidermal growth factor receptor (EGFR) mutation analysis showed the presence of exon 19 deletion within the tumor specimen. The patient was staged as advan- ced disease and was hence started with 250 mg of Geftinib, an EGFR tyrosine kinase inhibitor (TKI) daily. Four months later CT scan showed shrunken primary lesion with multiple cysts of variable sizes bilaterally (Figure 1 D–F). Choriocarcinoma and renal cell carcinoma are the usual culprit of cannon ball metastases in the lungs. Other rare causes include prostate cancer, endometrial malignancy, synovial sarcoma, hepato- Figure 1. A–C: Axial CECT images (lung window) at different levels done before initiating EGFR TKI treatment showing heterogeneously enhancing lesion measuring 52 × 51 mm in posterior segment of the right upper lobe (RUL) reaching up to the hilum, abruptly cutting off the RUL posterior segmental bronchus along with multiple nodular lesions consistent with cannon ball metastases (arrows) diffusely scattered without any lobar predilection. Few of these metastatic lesions have central cavitation (curved arrows). A small amount of pleural effusion is also seen; D–F: Axial CECT images at corresponding levels obtained after 4 months of EGFR TKI therapy showing reduced RUL mass lesion (25 × 12 mm). Although the majority of cannon ball lesions have disappeared completely, some have transformed into thin-walled cysts of varying sizes (block arrows). Few areas are left with only ground glass nodules A B C D E F