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In lymphoma, Positron Emission Tomography-Computerized Tomography (PET-CT) provides greater prognostic information than conventional imaging. However, false positivity occurred particularly in the head & neck due to predilection for infection and inflammation. We investigated the association between positive scans in the head & neck at the end of therapy with histology, and its diagnostic and prognostic values. 488 PET-CT were retrospectively assessed in 2012-2016 (40 months). Positive uptakes in the head & neck (five-point scale ≥4) were biopsied. Prevalence of positive scans was 10.9% (53/488). Two positive scans were histologically lymphomatous with mean maximum standardized uptake value (SUVmax) of 9.0±2.69. False positivity (96.2%) was histologically attributed to reactive lymphoid hyperplasia (SUVmax 9.0±3.88). Positive and negative predictive values, sensitivity and specificity were 3.8%, 100%, 100% and 89.5%, respectively. False positivity was associated with age, gender, extra-nodal involvement, Eastern Cooperative Oncology Group score (ECOG), positivity only in the head & neck and its pattern of positivity. No significant predictors were identified. Hodgkin Disease (HD) was more likely to have positivity only in the head & neck compared to Non-Hodgkin Lymphoma (NHL) (p=0.019). 106 patients with negative scans remained negative during study period, hence regarded as true negatives. Positive scans in the head & neck at post therapy yielded high false positivity and should not be routinely performed. HD has higher likelihood of scan positivity only in the head & neck than NHL. The value of PET-CT to detect true lymphomatous relapse in selected high-risk patients remained to be confirmed in future trials.

Introduction Crohn’s disease (CD) is an inflammatory disease with an increasing incidence and can involve any part of the gastrointestinal tract. Most cases are seen in young adults presenting with abdominal pain and diarrhea. This condition may lead to complications such as stricture and fistula. Besides, there is an increased risk of colorectal cancer and some extraintestinal cancers in these patients, due to chronic inflammation. One of the therapeutic options for Crohn’s patients is the use of immunomodulators. Such agents can induce remission and limit the usage of steroids. According to some literature, this treatment can increase the risk of colorectal cancer as well as extraintestinal cancers, of which skin cancers and lymphoma are the most prevalent. Lymphoma can be a result of chronic inflammation or use of immunomodulators such as azathioprine and 6-mercaptopurine (6-MP). Case Presentation In this literature, we describe a young man with rectorrhagia who is diagnosed with Crohn’s disease and a coexistence of lymphoma at the time of diagnosis, without a history of immunomodulator therapy. Conclusions With attention to the increased risk of colorectal and extraintestinal cancer in Crohn’s patients, assessment for early diagnosis should be considered