metabolic flare phenomenon mimicking disease progression on 18flouride– fluorodeoxyglucose pet/ct scan in breast cancer treated with paclitaxel-based chemotherapy

18f-fluorodeoxyglucose positron emission tomography (18f-fdg pet/ct ) is now being used as a single modality for metastatic workup and response evaluation in breast cancer. an increase in metabolic activity indicates disease progression; however, metabolic flare should be kept in mind. metabolic flare is a well-documented phenomenon reported in metastatic breast and prostate cancer. despite a favorable response to therapy, there is a paradoxical increase in radiopharmaceutical uptake. the flare phenomenon with various chemotherapeutic and hormonal agents is well acknowledged in bone scintigraphy. however, very few cases have been documented on pet/ct. increased uptake may be noted after treatment is instituted. the increased osteoblastic activity is associated with the healing response of bone tumors. we report a case of treated breast cancer. she presented with metastatic recurrence after four years of initial management. the patient was started on paclitaxel chemotherapy. serial 18f- fdg pet/ct demonstrated metabolic flare and complete metabolic response.