Epstein-Barr Virus-Positive Mucocutaneous Ulcer Mimicking Rectal Carcinoma at 18F-FDG PET/CT.

We report focally intense F-FDG PET/CT rectal activity (SUVmax = 25) with a horseshoe distribution in an 81-year-old man with B-cell chronic lymphocytic leukemia and suspected Richter transformation. While imaging findings were typical for rectal adenocarcinoma, histology revealed Epstein-Barr virus-positive mucocutaneous ulcer.

Retroperitoneal Endometriosis: A Possible Cause of False Positive Finding at (18)F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

Endometriosis is a frequent and clinically relevant problem in young women. Laparoscopy is still the gold standard for the diagnosis of endometriosis, but frequently both morphologic and functional imaging techniques are involved in the diagnostic course before achieving a conclusive diagnosis. We present a case of a patient affected by infiltrating retroperitoneal endometriosis falsely interpreted as a malignant mass by contrast-enhanced magnetic resonance imaging and (18)F-fluorodeoxyglucose positron emission tomography/computed tomography.

Lobular breast carcinoma: a case of rare possible 18F-FDG PET/CT and bone scan false negative.

A patient with diffuse osteosclerotic bone metastases from invasive lobular breast carcinoma is presented with both F-FDG PET/CT and bone scans negative for hypermetabolic lesions. Skeletal metastases were documented by CT and bone marrow biopsy, and high increased CA 15-3 level was recorded. This case report points to the potential risk of false-negative FDG PET and bone scans examination in lobular carcinoma type.