The great mimicker: pulmonary adenocarcinoma with interstitial lung disease-like presentation

Invasive mucinous adenocarcinoma, a rare subtype of lung adenocarcinoma, often presents with discrete tumours rather than diffuse interstitial involvement, leading to difficulties in diagnosis, which can mimic benign lung conditions.Initial imaging findings such as cystic changes and ground-glass opacities may suggest interstitial lung disease, potentially resulting in an unnecessary autoimmune workup. This emphasizes the importance of considering lung cancer in patients with significant smoking history and worsening respiratory symptoms.Bronchoalveolar lavage cytology may fail to identify malignant cells in cases of mucinous adenocarcinoma due to its lepidic growth pattern. This highlights the need for histopathological confirmation through biopsy to avoid false negatives and ensure appropriate management.