A 66-year-old woman was referred to our hospital with two pulmonary nodules that developed after PPC resection and subsequent adjuvant chemotherapy 5 years earlier. She underwent ileocecal resection and low anterior resection of the involved rectum, which yielded a 6.0-cm-sized PPC mass (Fig. 1a). The mass was initially considered mesenteric, and the lack of ovarian or uterine abnormalities or involvement on preoperative radiological examinations and intraoperative findings led to a strong suspicion of a gastrointestinal stromal tumor of the ileum. The distal end of the right fallopian tube was resected because of tumor involvement. The ovaries and uterus were considered normal and thus were not resected. Histopathologically, the tumor mass comprised irregular clusters of malignant cells with cellular papillae or slit-like glandular spaces (Fig. 1b), with or without psammoma bodies. The tumor cells contained atypical large nuclei, prominent nucleoli, and frequent mitoses. Immunohistochemically, these cells were positive for Wilms tumor (WT)-1 (Fig. 1c), cytokeratin (CK) 7, paired box gene 8, and estrogen receptor and negative for CK20, caudal-type homeobox 2, and villin. The mass was diagnosed as PPC based on the diagnostic criteria of the Gynecologic Oncology Group [1, 2]. Ascites and lymph node metastasis were not observed. Thus, tumor resection was considered complete (R0). She underwent six adjuvant chemotherapy cycles with paclitaxel (175 mg/m2) and carboplatin [area under the curve (AUC): 5].
Follow-up computed tomography showed a 1.3-cm-sized nodule in the left lung with a small airspace in the posterior basal segment (Fig. 2a) and a 0.9-cm-sized solid nodule in the apico-posterior segment that grew slightly during a 2-month period. No pleural effusion was detected. 18F-Fluorodeoxyglucose (FDG)-positron emission tomography (PET) revealed maximum standardized uptake values of 7.11 and 2.46 for these nodules. Both nodules were suspected to be pulmonary metastases of PPC. However, the serum cancer antigen (CA)-125 level was within normal range (11.7 U/ml). Because the serum CA-125 level was elevated (529.1 U/ml) before the first surgery, primary lung cancer or non-malignancy was also suspected. No evidence of tumor in the primary site was observed on FDG-PET or abdominal computed tomography.
Pulmonary wedge resection is now considered a standard surgical procedure for the treatment of metastasis from cancers in other organs. Therefore, if an intraoperative frozen examination could diagnose the nodules as metastatic PPCs, we would select wedge resection. As a result, the intraoperative frozen section examination of the resected lung specimen could not distinguish metastatic PPC from primary lung adenocarcinoma. Regarding surgical treatment of small-sized primary lung cancer, anatomical segmentectomy is gaining popularity as a curative and less-invasive procedure [4]. Accordingly, even if the two pulmonary nodules were primary lung cancers, not pneumonectomy (double lobectomies), but the respective segmentectomies would be suitable owing to the invasiveness.
From all the above, regardless of the definitive diagnosis (metastatic PPC or primary lung cancer), anatomical segmentectomies of the two nodules were deemed to be suitable, considering curativity and invasivity. Anatomical segmentectomies of the posterior basal segment and superior division with systematic lymph node dissection were performed. Histological examination of the resected specimen (Fig. 2b) revealed neoplastic cells in the lung tumor. These cells contained enlarged nuclei, irregular slit-like spaces, and a papillary pattern, similar to previous PPC (Fig. 2c). Immunohistochemically, the specimen was positive for WT-1 and negative for thyroid transcription factor-1. These findings led to a diagnosis of a pulmonary recurrence of the previously resected PPC. No mediastinal or hilar lymph node metastasis was observed. The postoperative course was uneventful, and second-line chemotherapy with paclitaxel (175 mg/m2) and carboplatin (AUC 5) for six cycles was initiated.
