The Gray Man of Smoke and Shadows by Todd Sullivan

Therefore, for purposes of this discussion, a cavity will be defined as any radiographic opacity with an internal area of lucency, regardless of wall thickness.Ī cavity is the result of any of a number of pathological processes including suppurative necrosis (e.g., pyogenic lung abscess), caseous necrosis (e.g., tuberculosis), ischemic necrosis (e.g., pulmonary infarction), cystic dilatation of lung structures (e.g., ball valve obstruction and Pneumocystis pneumonia), or displacement of lung tissue by cystic structures (e.g., Echinococcus) ( 204). Other air-filled pulmonary lesions such as emphysematous bullae may also be radiographically indistinguishable from cavities ( 212). However, bronchogenic cysts may contain air and have been confused with more typically cavitary lesions such as lung abscesses, fungal infections, or tuberculosis ( 7). For example, bronchogenic cysts are benign developmental abnormalities of the lung that usually appear to be homogeneous masses with the density of water. Unfortunately, considerable overlap in etiology and pathophysiology exists between these two categories. Some have tried to make this distinction by defining cysts as being air-containing spaces surrounded by a thin (4 mm or less) wall and cavities as being as air-containing spaces with walls that are at least 5 mm thick ( 322). In theory, one would like to distinguish a cavity from other air- or fluid-filled lung structures with different pathophysiologies, but in practice, this is not always possible.

A cavity has been defined in the radiology literature as (pathologically) “a gas-filled space within a zone of pulmonary consolidation or within a mass or nodule, produced by the expulsion of a necrotic part of the lesion via the bronchial tree” and (radiographically) “a lucency within a zone of pulmonary consolidation, a mass, or a nodule hence, a lucent area within the lung that may or may not contain a fluid level and that is surrounded by a wall, usually of varied thickness” ( 368).

The Gray Man of Smoke and Shadows by Todd Sullivan