Superior mediastinal shift in right-lower-lobe collapse: the "upper triangle sign".
In some patients with right-lower-lobe collapse a triangular shadow was seen in the right upper lung field, continuous with the mediastinum and with its apex pointing toward the right hilus. This represents a shift of the upper anterior mediastinum to the right and may be mistaken for right-upper-lobe collapse or an infiltrate by the unwary observer. This finding, which the authors call the "upper triangle sign," occurs frequently enough in cases of significant right-lower-lobe collapse to be a useful diagnostic sign.
D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011012:Pneumomediastinum, Diagnostic; D001261:Pulmonary Atelectasis / Q000000981:diagnostic imaging* / Q000209:etiology; D011859:Radiography