[A case of diffuse pneumonic type of mucinous adenocarcinoma treated with reduction surgery].

A female never-smoker in her 60s presented with persistent productive cough. Chest radiography and computed tomography revealed widespread consolidation in the basal area of her left lung lower lobe. She received antibiotics and steroid therapy. Nevertheless, consolidation extended over the left lower lobe, and multiple nodular shadows appeared in both the lungs until a histological diagnosis of adenocarcinoma was obtained with lung wedge resection biopsy. Left lower lobectomy was performed as a tumor reduction surgery to palliate dyspnea due to massive sputum. The duration of decreased sputum production was short, and the lesion spread rapidly over the residual lung, resulting in death due to respiratory failure 8 months after her first visit. The histological diagnosis was diffuse pneumonic type of invasive mucinous adenocarcinoma with lepidic, acinar, and solid growth patterns (formerly mucinous bronchioloalveolar cell carcinoma). Mucous sputum containing tumor cells tends to spread aerogenously to other lobes and both lungs, and thus, disease control is difficult. Although there are some case reports of successful treatment with oral epidermal growth factor receptor tyrosine kinase inhibitors or pemetrexed, an effective therapeutic strategy for this type of lung cancer has not been established.