Recurrent Pneumonia? A Case of Availability Bias and Anchoring.

Invasive mucinous adenocarcinoma is a multi-centric adenocarcinoma that accounts for less than 5% of all lung cancer diagnoses. The most common presenting symptoms (cough, sputum production, and chest pain) in conjunction with its radiographic findings (patchy, multi-lobar infiltrates) make invasive mucinous adenocarcinoma challenging to distinguish from both infectious and inflammatory pneumonia. However, due to its aggressive nature, invasive mucinous adenocarcinoma should be considered if a presumed case of pneumonia lacks symptoms of infection (e.g., fever, leukocytosis) and/or does not respond to antibiotics. We report the case of a 75-year-old male who was admitted in the setting of a presumed case of recurrent pneumonia, which had failed to respond to prior antibiotic therapy. Further workup, including trans-bronchial biopsy, confirmed mucinous adenocarcinoma with a lepidic pattern. This case highlights the importance of establishing a broad differential in the setting of unresolved pneumonia following appropriate antibiotic coverage.