Extensive goblet cell metaplasia of the peripheral lung may harbor precancerous molecular changes: comparison of two...

We present two cases of extensive goblet cell metaplasia in the peripheral lung. The first case was a 72-year-old male with a nodule (12 × 10 mm) detected by CT. Macroscopically, it contained abundant mucin; histopathologically, goblet cells were predominant, whereas ciliated and basal cells were sparse. A KRAS G12V mutation was detected. In the pulmonary background of this case, scattered tiny foci of goblet cell metaplasia were present. The second case was a 71-year-old female with a nodule (7 × 5 mm) detected by CT. It contained abundant mucin, and microscopically, various cell types were intermingled. Although the nodule mainly comprised goblet cells, ciliated and basal cells were also easily identified. No KRAS mutation was found in this patient. Dispersed minute foci of goblet cell metaplasia were identified in the pulmonary background. Therefore, we suspect that airway irritants may have contributed to the changes that occurred in the pulmonary background of both cases. We propose that the tendency of goblet cells to overwhelm other cell types in the metaplastic epithelium may be an indicator of precancerous molecular changes.