Neoplastic Fever with Hyperprocalcitoninemia—a Case Report

When a patient with malignancy presents with fever and an elevated inflammatory response, it is often difficult to distinguish whether they have a bacterial infection or neoplastic fever. Identifying the cause is important, given that antibiotic therapy is required for bacterial infections, whereas steroids are indicated for progressive malignant disease. Procalcitonin has been found to be specifically elevated in sepsis and in bacterial infections and to be useful for differentiating bacterial infections from nonbacterial conditions. In addition, it has been reported that monitoring the trend of procalcitonin levels after treatment initiation is useful for differential diagnosis. Here we report a case of neoplastic fever that presented with hyperprocalcitoninemia without infection. The patient was a 65-year-old Asian man who developed fever on the day after completion of radiotherapy for lumbar metastases from colon cancer. At that time, blood tests showed a marked inflammatory response, especially elevation of procalcitonin to 50 ng/mL. No obvious focus of infection was found based on computed tomography, urine tests, and physical examination. However, based on the laboratory findings (especially significant procalcitonin elevation) and the patient’s deteriorating overall status, bacterial infection was diagnosed and antibiotics were administered. However, blood and urine culture tests were negative and no further episodes of fever were observed. Blood tests performed 3 days after the start of antibiotic therapy revealed that his procalcitonin level was still high. Therefore, hyperprocalcitoninemia due to neoplastic fever was diagnosed and he was switched from antibiotics to steroids. The patient’s inflammatory response subsided, his procalcitonin level decreased, his overall condition improved, and he was discharged from hospital. Measurement of procalcitonin is useful for identifying non-infectious pathology because of its high specificity and early elevation in bacterial infections. Since procalcitonin levels are also correlated with the severity of sepsis, a high level indicates a higher likelihood of sepsis. Therefore, when procalcitonin is elevated, a bacterial infection is highly likely and antibiotic therapy is required. However, because false-positive results can occur as a result of surgical invasion, multiple metastases, and cytokine storms, a diagnosis of neoplastic fever should be made based on multiple findings and clinical features. Furthe