The pitfall in evaluating several serological markers of Pneumocystis carinii pneumonia in a neutropenic patient.

We compared the significance of several serum markers to evaluate the activity of Pneumocystis carinii pneumonia (PCP) in an immunocompromised patient. We successively measured KL-6, an amino-terminal propeptide of Type III procollagen (PIIINP), and the cytokeratin 19 fragment (CK19) in the sera of a patient with PCP. Interestingly, PIIINP, KL-6, and CK19 levels in the sera did not increase at the time of onset of PCP during a neutropenic phase. Instead, they markedly increased after the recovery of WBC counts. This case suggests that values of PIIINP, KL-6, and CK19 used for monitoring the activity of PCP might be underestimated in neutropenic patients.