Discordant Cavitary Changes: A Radiological Dilemma in Invasive Mucinous Adenocarcinoma: A Case Report

Treatment-related cavitary transformation in lung cancer may complicate radiological response assessment. We report a man in his 70s with stage IVA invasive mucinous adenocarcinoma treated with atezolizumab, bevacizumab, carboplatin and paclitaxel. After two cycles, CT showed enlargement of cavitary components despite regression of solid tumour components, making response assessment difficult. After two additional cycles, the pulmonary lesions showed little change, whereas progression of the Th4 bone metastasis led to an overall assessment of progressive disease and a change to docetaxel plus ramucirumab. Thereafter, the cavities further enlarged while the cavity walls progressively thinned and the solid components appeared to regress. This case illustrates that marked multifocal cavitary transformation may produce discordant morphological changes, limiting response assessment based on imaging alone. Serum CEA and SLX levels remained within the normal ranges at diagnosis and throughout treatment.