Giant cell carcinoma of the lung (GCCL) is an uncommon and extremely aggressive variant of
lung cancer. Characteristic microscopic findings include marked pleomorphism, aggregates of mononucleated or multinucleated giant cells (or both), a general lack of architectural cohesiveness, extensive
necrosis, and endocytosis by the giant cells. Although the epithelial character of GCCL has been confirmed by a number of studies, controversy persists as to whether it represents a variant of poorly differentiated
adenocarcinoma or of
squamous carcinoma. Histochemical studies for mucosubstances have yielded variable and conflicting results. This report describes conventionally fixed and processed samples from 10 cases of GCCL studied with a panel of
monoclonal antibodies (Mabs) recognizing different
cytokeratin polypeptides (AE1, AE3, AE1/AE3 cocktail, and CAM 5.2),
vimentin, and Mab A-80, the last of which binds to a mucinous
glycoprotein associated with exocrine differentiation. All 10 cases of GCCL reacted with all
cytokeratin Mabs; the extent and intensity of the reaction varied notably. All cases stained strongly and diffusely with Mab AE1 and AE1/AE3, the reaction was less extensive and weaker with CAM 5.2. Significantly, 2 cases reacted focally with Mab AE3. Nine cases reacted extensively and intensely with the
vimentin Mab, often showing prominent paranuclear globular profiles. All cases reacted with Mab A-80; the reaction was often strong, but the extent was variable. Findings indicate that all GCCL are indeed
cytokeratin positive but that most express
polypeptides toward the low-molecular weight end of the spectrum; a small subset also expresses heavier
polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)