Osteoclast-like giant cell–rich carcinomas of the lung: a clinicopathological, immunohistochemical, and molecular study of 3 cases

Summary Three cases of primary carcinomas of the lung each with an extensive osteoclast-like giant cell component are presented. The patients are 3 men between the ages of 58 and 67 years (average, 62.5 years) who presented with nonspecific symptoms. A history of malignancy, infectious, or granulomatous disease was negative in all the patients. Diagnostic imaging disclosed the presence of a large intrapulmonary mass; in 1 case in the right upper lobe and in 2 cases in the right lower lobe. Surgical resection via lobectomy was performed in the 3 patients. Grossly, the tumors were described as soft, friable intrapulmonary masses, reddish in color, and measuring from 6 to 13 cm in largest diameter. Histologically, the tumors were each characterized by the extensive presence of a multinucleated osteoclast-like giant cell component, which represented approximately 80% of the tumor mass. The osteoclast-like giant cell component was admixed with a sarcomatoid carcinoma in 2 cases and an adenocarcinoma in 1 case. Immunohistochemistry showed that the osteoclast-like giant cells were positive for CD-68, cathepsin K, and histone H3, whereas the carcinoma component was positive for keratin, thyroid transcription factor-1, and histone H3 (patchy). Molecular studies were performed in 2 patients with negative results. Clinical follow-up was obtained in 2 patients; 1 died 14 months after initial diagnosis, whereas 1 remains alive 6 months after initial diagnosis. One patient was lost to follow-up. The current neoplasms represent an unusual type of lung carcinoma that needs highlighting as a separate type from conventional giant cell carcinoma.