False Positivity and False Negativity on Positron Emission Tomography in a Patient with Lung Cancer

Lung cancer is the leading cause of cancer-related deaths worldwide and non-small cell lung cancer (NSCLC) accounts for about 85% of the cases. Since its introduction in 2001, positron emission tomography (PET-CT) has been used in early diagnosis, staging, early and accurate detection of recurrences. In this report, we wish to present a case of lung cancer who was upstaged after thoracotomy and lymph node dissection despite a first evaluation with PET-BT and also, during follow up, the patient was misdiagnosed as a recurrence due to false positive uptake on PET-BT. Interestingly, the patient also had a synchronous testicular tumor which was not smoking-related. In this case, the false positive and false negative results of PET-BT was seen in the same patient. Additionally, the patient had a seminoma accompanying the lung cancer, which was not reported previously. Clinicians who deals with management of lung cancer should keep in mind that PET-BT may cause false positive and false negative results, so histopathological confirmation is necessary, and multiple independent primary tumors may accompany to lung cancer, even non-tobacco related ones, but it does not seem to be effective in the prognosis of the patient.