[1643] Primary Oncocytic Adenocarcinoma of the Lung: Clinicopathological and Immunohistochemical Study of 16 Cases

LM Solis, MG Raso, C Behrens, I Wistuba, CA Moran. The University of Texas MD Anderson Cancer Center, Houston, TX

Background: Oncocytic carcinomas originating primarily in the lung parenchyma are rare and lack full characterization as primary pulmonary neoplasms.
Design: To investigate the frequency of lung adenocarcinomas having oncocytic features we reviewed 566 primary lung adenocarcinomas surgically resected with curative intent in our institution between 1997 to 2005, and performed a detailed histopathological and immunohistochemical analysis and correlation with patients clinical information.
Results: We classified 16 (3%) cases as oncocytic adenocarcinoma. The patients were 11 women and 5 men with age ranging from 47 and 81 years (median 75 years). Fourteen patients (88%) were tobacco smokers. Thirteen patients underwent lobectomy and 3 wedge resection as initial treatment. Thirteen patients (81%) were in pathological stage I; while the remaining 3 patients were in stages II, III, and IV, respectively. Macroscopically, the tumors ranged in size from 1.2 to 7 cm in greatest diameter. Histologically, the tumors showed four distinct growth patterns: bronchioloalveolar, acinar, solid, and papillary. The tumors were composed of cells with abundant eosinophilic cytoplasm, round to oval nuclei, and prominent nucleoli; while in 7 cases areas of necrosis were present. Mitotic figures were present in the range of 1 to 8 per 10hpf. Immunohistochemical studies were performed in 14 cases: all tumors showed positive staining for keratin 7 and TTF-1, and were negative for thyroglobulin. Keratin 20 immunostaining was observed focally in two cases. Four tumors that were analyzed for EGFR and 3 for KRAS mutations demonstrated to be wild-type. Clinical follow up for recurrence free and overall survival was performed for at least 2 years in all cases: 14 (88%) patients were alive, and 12 (75%) did not have recurrence.
Conclusions: The cases herein presented highlight an unusual feature in primary lung adenocarcinoma that may pose a problem in the evaluation of these tumors. The oncocytic characteristics present in our cases represent a distinct histological feature important to recognize in primary lung adenocarcinomas. The use of immunohistochemical studies may prove beneficial in the final evaluation of these tumors (Supported by DoD grant VITAL W81XWH-04-1-0142).
Category: Pulmonary

Monday, March 9, 2009 1:00 PM

Poster Session II # 225, Monday Afternoon