FIGURE 4.

Classification of cyst-related primary lung malignancies may be prone to interobserver variation. a, b) Cyst-related lung cancer in a 74-year-old male proved to be squamous cell carcinoma after resection. Morphologically, it might be characterised as a type 2 lesion due to its endophytic solid component (a), as a type 1 lesion due to its exophytic solid component more caudally (b), or maybe as a type 3 lesion due to the asymmetrical wall thickening (a). c, d) Cyst-related lung cancer in a 60-year-old female with synchronous small cell lung carcinoma in the left upper lobe. This lesion was not acknowledged as a suspect finding. It might be characterised as a type 1 lesion due to exophytic solid components (c), as unclassifiable because of two separate exophytic solid components (c), or maybe as a type 3 lesion because the most cranial solid component in a coronal plane shows more asymmetrical wall thickening (d).