CTICasesTipped-Up Right Middle Lobe (Chronic Cicatrization Atelectasis)
Imaging findings
Frontal and lateral radiographs showed a triangular opacity that was more conspicuous because of a lordotic projection, corresponding on CT to chronic volume loss of the right middle lobe with patent but mildly narrowed bronchi. The classic "wedge within a wedge" appearance was demonstrated, in which a larger wedge (right lower lobe, continuous with the major fissure) and a smaller wedge (right middle lobe, continuous with the minor fissure) together produce the triangular density on a lordotic frontal view, representing a tipped-up variant of right middle lobe collapse.
Key takeaways
A triangular opacity seen only on a lordotic frontal radiograph should raise the tipped-up right middle lobe collapse variant rather than a discrete mass, and recognizing the "wedge within a wedge" sign (contributions from both the collapsed right middle lobe against the minor fissure and an expanded right lower lobe against the major fissure) prevents misinterpretation of this classic pre-CT-era radiographic sign; in this patient the chronic right middle lobe atelectasis reflected long-standing cicatrization rather than acute obstruction.
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