Unique clinicopathological characteristics of pulmonary squamous cell carcinoma with part-solid nodule

Chest high-resolution computed tomography (HRCT) finding of part-solid nodule (PSN) is related to pulmonary adenocarcinoma (AC) with lepidic growth. We recently experienced a pulmonary squamous cell carcinoma (SCC) showing PSN pattern on HRCT. We present a 70-year-old man who had a small nodule with PSN pattern in the right lung field on HRCT. After clinical diagnosis of AC, lobectomy was performed. The tumour was pathologically diagnosed as SCC with lepidic growth. Histopathologically, the central area of the tumour showed keratinizing SCC, whereas the peripheral area revealed lepidic SCC cell growth between non-neoplastic type II pneumocytes and alveolar basement membrane. On the basis of the present case and five from the literature, SCC with lepidic growth had the following clinical characteristics: peripheral location, early stage detection, clinical misdiagnosis as AC, less progression, and favourable prognosis. This case may be a special type of SCC with less progression and favourable prognosis.