can positron emission tomography and computed tomography be a substitute for bone marrow biopsy in detection of bone marrow involvement in patients with hodgkins or nonhodgkins lymphoma introduction positron emission tomography and computed tomography petct has become an important part of staging and treatment evaluation algorithms of lymphoma we aimed to compare the results of petct with bone marrow biopsy bmb with respect to bone marrow involvement bmi in patients with hodgkins lymphoma hl and aggressive nonhodgkins lymphoma anhlmethods the medical files of a total of 297 patients diagnosed with hl or anhl and followed at the hematology clinics of 3 major hospitals in stanbul between 2008 and 2012 were screened retrospectively and 161 patients with classical hl and anhl were included in the study the patients were referred for petct and bmb at the initial staging bmb was performed as the reference standard for the evaluation of bmiresults there were 61 38 hl and 100 62 anhl patients concordant results were revealed between petct and bmb in 126 patients 78 52 hl 74 anhl 20 with positive petct and bmb results and 106 with negative petct and bmb results there were discordant results in 35 patients 9 hl 26 anhl 16 of them with positive bmb and negative pet ct results and 19 of them with negative bmb and positive petct resultsdiscussion and conclusion we observed that petct is effective to detect bmi despite it alone not being sufficient to evaluate bmi in hl and anhl bone marrow trephine biopsy and petct should be considered as mutually complementary methods for detection of bmi in patients with lymphoma in suspected focal involvement combining biopsy and petct might improve staging results