Eight clinically significant variables were analyzed, identifying five independent predictors for distinguishing PJP from BP: previous immunomodulator use (p = 0.025, OR 0.21), PCT (p = 0.013, OR 0.19), inflammatory lesion volume/total lung volume (p = 0.015, OR 1.09), whole lung −700 to −450 HU pneumonia lesion volume (=0.042, OR 1.01), and whole lung −450 to −300 HU pneumonia lesion volume (p = 0.025, OR 0.98). The gene discussed is CALCA; the disease is pneumocystosis.