Diffuse thallium lung uptake in Pneumocystis carinii pneumonia.

Five patients with AIDS with Pneumocystis carinii pneumonia (PCP) showed diffuse bilateral lung uptake on sequential thallium and gallium scans. This creates a problem in the sequential use of these tests for the differentiation of Kaposi's sarcoma from acute inflammatory or other malignant diseases. In Kaposi's sarcoma, thallium uptake is usually focal and not diffuse unless associated with other pathology. However, in PCP the diffuse thallium lung uptake may be due to congestion, increased vascular permeability, and extravasation of thallium into the lung parenchyma.