Follow-up imaging in the same patient after tacrolimus withdrawal and initiation
of rituximab induction therapy. Despite initial improvement, the patient
presented with fever, abdominal pain, and bloody diarrhea after 2 months, before
starting chemotherapy. (A) PET/CT image reveals improved uptake
levels of the pulmonary masses (black arrows), but intense, diffuse, pancolonic
fluorodeoxyglucose uptake was detected, compatible with active colitis (yellow
arrow). (B) Corresponding coronal CT image reveals characteristic
“lead-pipe” colon (white arrow), indicating clinical suspicion of
ulcerative colitis exacerbation secondary to rituximab. Laboratory test results
ruled out infection. Low-dose corticosteroid treatment was started with
immediate clinical improvement.