A complicated pulmonary hydatid cyst resembling a tumour in an adult on PET scan: a case report.

Complicated pulmonary cysts have a wide range of possible diagnoses with different approaches as they can be benign or malignant. They can resemble malignancies in symptoms and imaging, mainly on positron emission tomography (PET) scan, which can increase the false positivity. We present an infected hydatid cyst resembling a malignancy as it presented with weight loss in a smoker and had necrosis and malignance features on computed tomography and PET scans. However, serology tests and fine needle aspiration were suggestive of a hydatid cyst, which made this case quite unique. Other diagnoses should always be suspected even if the malignancy was highly likely due to other lesions can resemble malignancies.