Mesenteric panniculitis (MP) is an uncommon, benign, condition that involves the mesenteric root. It may be idiopathic, or be associated with an inflammatory or malignant neoplasm. Aim: To establish the frequency of MP in oncologic patients according to the type of cancer. Method: Images of PET/ CT performed between January 2008 and December 2019 on recently diagnosed oncologic patients were reviewed searching for MP. MP was defined as increased density and volume of mesenteric root fat, associated with nodules and/or lymph nodes, with or without pseudocapsule. Patients who had received previous cancer treatment or those with synchronous or metachronous malignancies were excluded. Results: The frequency of MP in the total oncologic population was 5,3 % (82/1539). Types of cancer frequently associated with MP were non-Hodgkin lymphoma at 15,9% (31/195) and prostate cancer at 11,9% (16/134), both significantly higher than the rest of the malignancies (p < 0,01). Hodgkin Lymphoma (0/59), carcinoma of the cervix (0/45), and endometrial cancer (0/44) did not show MP. Conclusion: MP is more frequently associated with some malignant neoplasms, such as non-Hodgkin lymphoma and prostate cancer, and rare in others. This must be considered when studying patients with MP detected incidentally.