Abstract
The micropapillary pattern has long been recognized as a poor prognostic factor for breast, ovarian, and bladder cancers, and micropapillary lung cancer has been increasingly reported in recent years. We recently encountered a patient with a small peripheral adenocarcinoma of the lung with lymph node metastasis. The patient was a 52-year-old man whose chest CT showed an irregularly bordered nodule in the left S3 segment, approximately 15 mm in diameter, with a pleural depression and spicula. Under a preoperative diagnosis of stage IA (cT1N0M0) adenocarcinoma of the left lung, left upper lobectomy with ND2a was performed. Histological examination revealed a micropapillary pattern lacking a fibrovascular core. Immunohistologically, the tumor cells were TTF-1 (+), CK7 (+), SP-A (+), and CK20 (-), leading to a diagnosis of primary lung cancer. Lymph node and intrapulmonary metastases were observed, and the pathological diagnosis was pT1N2M0, stage IIIA. Even a small pulmonary nodule should be promptly diagnosed, keeping in mind the presence of a histological pattern, as seen in this patient.
