Primary oncocytic adenocarcinomas of the lung: A clinicopathologic, immunohistochemical, and molecular biologic analysis of 16 cases

Sixteen cases of primary oncocytic adenocarcinomas of the lung are reported. The patients were 11 women and 5 men between the ages of 47 and 81 years (median, 75 years) with symptoms of cough, chest pain, and shortness of breath. Surgical staging disclosed 14 patients (88%) with stage I disease, 1 (6%) with stage II, and 1 (6%) with stage III. Histologically, all the cases displayed prominent oncocytic features with conventional growth patterns, including acinar, papillary, and bronchioloalveolar. Immunohistochemically, the tumors displayed positive staining for keratin 7, thyroid transcription factor-1, and mitochondrial antibody. Molecular studies showed 3 (20%) of 15 tumors with EGFR mutations and 3 additional cases with KRAS mutations. Clinical follow-up of at least 24 months was obtained in all patients and showed that 5 patients had recurrences, 2 patients died of tumor, and 2 other patients died of unrelated conditions. These cases represent an unusual variant of pulmonary adenocarcinoma.