Giant cell carcinoma of the lung (GCCL) is a rare histological form of undifferentiated lung cancer traditionally classified within the non-small cell lung carcinomas. The characteristic feature of this highly lethal malignancy is the distinctive light microscopic appearance of its extremely large cells, which are bizarre and highly pleomorphic, and which often contain more than one huge, misshapen, pleomorphic [[cell nucleus|nucleus] ("syncytia"), which result from cell fusion.

Although it is common in the lung cancer literature to refer to histologically mixed tumors containing significant numbers of malignant giant cells as "giant cell carcinomas", technically a diagnosis of "giant cell carcinoma" should be limited strictly to neoplasms containing only malignant giant cells (i.e. "pure" giant cell carcinoma).

Aside from the great heterogeneity seen in lung cancers (especially those occurring among tobacco smokers), the considerable variability in diagnostic and sampling techniques used in medical practice, the high relative proportion of individuals with suspected GCCL who do not undergo complete surgical resection, and the near-universal lack of complete sectioning and pathological examination of resected tumor specimens prevent high levels of quantitative accuracy.

A giant cell is a mass formed by the union of several distinct cells (usually macrophages). It can arise in response to an infection or foreign body.

Types include:

Also

Foreign-body giant cells in the lung. H&E stain.

Foreign-body giant cell reaction to a suture. H&E stain.

CD68 immunostaining demonstrating giant cells and macrophages.

Cementoblasts & osteoclasts are found normally during the shedding of deciduous teeth. They are also found after tooth extraction.