KRAS mutation analysis helps to differentiate between pulmonary metastasis from colon adenocarcinoma in situ and primary lung adenocarcinoma.

摘要

A 69-year-old woman never-smoker was noted to have a olitary 4-cm lesion in the left upper lobe on routine preoperative chest x-ray before elective hip replacement. Chest computed tomography redemonstrated the spiculated 4 X 3.3-cm lesion. Positron emission tomography-computed tomography confirmed that the lesion was fluorodeoxyglu-cose-avid with no other sites of fluorodeoxyglucose avidity (Figure 1). The patient underwent a core needle biopsy of the lung lesion showing a cytokeratin (CK) 20 and caudal type homeobox transcription factor 2-positive adenocarcinoma, which was negative for CK7 and thyroid transcription factor-1. The expected immunohistochemical markers for a primary lung adenocarcinoma are CK7 and thyroid transcription factor-1, whereas the usual markers for a primary colo-rectal adenocarcinoma are COO and caudal type homeobox transcription factor 2. The patient underwent a video-assisted thoracoscopic lobectomy and mediastinal lymphadenectomy revealing a 3.8-cm adenocarcinoma with the same histologic (Figure 2A) and immunophenotype (Figure 3) as the previous biopsy.