Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 58 3 2020 07 19 134 137 Aamer Ubaid Department of Medicine, Khyber Teaching Hospital, Peshawar, Pakistan. Farishta Waheed Department of Medicine, Khyber Teaching Hospital, Peshawar, Pakistan Awais Naeem Department of Medicine, Khyber Teaching Hospital, Peshawar, Pakistan. 2019 09 01 2020 04 25 Echinococcus cystic infection is a zoonotic infection caused by the larval stage of cestode species belonging to the genus Echinococcus. Through the modulation of the immune system by this parasite, there is an established link of this infection with the metastasis and progression of a tumor. We present a case of a patient with synchronous findings of metastatic adenocarcinoma with unknown primary along with the previous history of echinococcal infection which highlights the need of prompt management of such infections with a regular follow up of such patients. https://acta.tums.ac.ir/index.php/acta/article/view/8058 https://acta.tums.ac.ir/index.php/acta/article/download/8058/5385