A 56-Year-Old Man With Fever, Anemia, and an Extremely High PCT Level

Abstract

INTRODUCTION: Procalcitonin has been routinely used as a marker of bacterial, parasitic, and fungal infections, with better specificity compared to ESR and CRP. An extremely elevated PCT level strongly argues for an infectious cause and signifies severity of infection. We present a case in which PCT level was shown to correlate with disease activity of diffuse large B cell lymphoma. CASE PRESENTATION: A 56 year old man presented with fever of 10-day duration, without obvious accompanying symptoms. Systemic physical examination showed no sign indicative of localized infection. CBC showed mild anemia, with normal WBC and differential. PCT level on admission was 2.7ng/ml. Serum (1,3)β-D-glucan and galactomannan tests were negative. An autoimmune panel was negative. We started the patient on moxifloxacin, piperacillin/tazobactam, and subsequently meropenem, but the patient began to have drenching fever of 41oC, with prominent weight loss of 7kg over ten days of hospitalization. Multiple sets of blood cultures were negative. PCT level took a dramatic rise to 5.48ng/ml on the fifth day and to 23.96ng/ml on the tenth day of hospitalization. Repeated CBC showed a normal WBC and differential, worsening anemia and thrombocytopenia. A PET-CT scan was performed and showed enlarged liver and spleen with homogenously elevated uptake of FDG. The SUV value was 2.8 in the liver and 10.4 in the spleen. Multiple small lymph nodes of no more than 1 cm in diameter were identified in the mesentery and retroperitoneal area, with normal FDG uptake. First bone marrow aspiration showed atypical lymphocytes. 10 days after admission, a repeated bone marrow aspiration was diagnostic of diffuse large B lymphoma. We started the patient on R-CHOP chemotherapy (R 600mg d0, CTX 1.1g d1, THP 75mg d1, VCR 2mg d1, prednisone 25mg d1-d5), and discontinued all the antibiotics for lack of solid evidence of infection except for an extremely elevated PCT level. On the second day of chemotherapy, the peak temperature declined to no more than 38oC, and one week later, the fever completely resolved. 3 days after chemotherapy, a repeat evaluation of PCT showed a result of 1.15ng/ml, which further decreased to 0.11ng/ml 15 days after chemotherapy. The patient remained afebrile thereafter. DISCUSSION: Serum PCT level has been integrated in routine clinical practice as a marker of bacterial, parasitic, and fungal infections, and also as a tool in therapeutic decisions in a few conditions, such as pneumonia, meningitis and pancreatitis. For patients with fever of unknown origin, PCT assessment is of great value to make a differential diagnosis between infectious causes from non-infectious causes, including autoimmune and malignant diseases. False positive elevation of PCT levels in autoimmune diseases have been studied, which indicated active Wegener's granulomatosis (WG), Kawasaki disease, and adult-onset Still disease could lead to high levels of PCT. There is a lack of data regarding to false positive PCT elevations caused by lymphoma or other malignancies. There have been two hypotheses regarding to the pathophysiology of PCT. It is thought to be induced either directly via microbial toxins or indirectly vi a a humoral or cell-mediated host response. Our case advocates the latter. CONCLUSIONS: Despite being a relatively specific marker for bacterial infection, PCT should not replace the necessary extensive diagnostic workup. Significant elevation of PCT level could be associated with lymphoma without infectious complication.