Peritoneal Lymphomatosis Mimicking Peritoneal Carcinomatosis from Ovarian Malignancy on F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Peritoneal lymphomatosis is relatively uncommon cause of diffuse malignant peritoneal disease, and differentiating it from other causes of diffuse peritoneal disease such as peritoneal carcinomatosis is often difficult on imaging. Common findings observed in peritoneal lymphomatosis in contrast to other etiologies include frequent nodal involvement and splenomegaly. We present a case of diffuse peritoneal disease along with ovarian lesions in the absence of abdominal lymphadenopathy or splenomegaly on fluorodeoxyglucose positron emission tomography–computed tomography in the setting of elevated cancer antigen-125 levels, mimicking primary ovarian malignancy causing peritoneal carcinomatosis, which was finally proven to be lymphoma.