Fever and rigors nine days after the first cycle of chemotherapy

A 52-year-old woman with newly diagnosed metastatic breast cancer was admitted to the oncology ward with fever and rigors. Nine days before presentation, she had received her first cycle of chemotherapy with docetaxel at a dose of 75 mg/m². As part of the regimen, she had been given dexamethasone 8 mg twice daily on the day before, the day of, and the day after chemotherapy, and ondansetron 8 mg twice daily for five days. She was also taking omeprazole 20 mg once daily for dyspepsia and prophylactic trimethoprim-sulfamethoxazole (80/400 mg) once daily for three weeks before the chemotherapy.

On the day of admission, her temperature was 39.2 °C, heart rate 104 beats per minute, respiratory rate 22 breaths per minute, and blood pressure 100/60 mmHg. She reported shaking chills but no cough, dysuria, or diarrhoea. Physical examination revealed a tender right breast mass and axillary lymphadenopathy, but no signs of a focal infection. There were no mouth ulcers, skin breaks, or signs of a central line infection.

Initial laboratory investigations showed a haemoglobin of 104 g/L, white cell count 0.4 × 10⁹/L, neutrophil count 0.1 × 10⁹/L, and platelet count 84 × 10⁹/L. C-reactive protein was 148 mg/L. Blood cultures, urine cultures, and a chest X-ray were all negative. She was diagnosed with febrile neutropenia.

She was treated with broad-spectrum antibiotics (piperacillin-tazobactam 4.5 g intravenously every 8 hours) and granulocyte colony-stimulating factor (5 µg/kg subcutaneously daily). Her fever settled within 48 hours and her neutrophil count recovered to 1.2 × 10⁹/L by day 4 of admission. She was discharged after six days. No further cycles of docetaxel were administered, and no rechallenge was attempted.

The differential diagnosis included infection, but no infective focus was identified and cultures were sterile. The potential role of concurrent drugs, especially trimethoprim-sulfamethoxazole, was considered, but the timing of the neutropenia was more consistent with the chemotherapy.