Under light microscopy, the<unk>  malignant pleomorphic<unk> s making up a GCCL resemble those found in choriocarcinoma, angiosarcoma, and some forms of true sarcoma, such as malignant fibrous histiocytoma and rhabdomyosarcoma. In some instances, they can also bear considerable resemblance to "activated" histiocytes seen in some inflammatory conditions. A rare and potentially difficult differential diagnostic dilemma occurs when GCCLs must be separated from pulmonary or mediastinal choriocarcinomas, a critical distinction to me made because while there is a known standard of care for treating choriocarcinoma, as yet there is no generally accepted specific standard treatment for GCCL. Careful review of<unk>  morphology is key to their delineation — while GCCLs show great variation in<unk>  size distributions and morphologies in tumors, choriocarcinomas consistently contain only syncytiotrophoblasts and cytotrophoblasts. GCCL and primary pulmonary choriocarcinoma can also be differentiated on the basis of ultrastructural features by electron microscopy, although EM is not yet widely applicable. Occasionally, a bone metastasis of a GCCL could potentially be mistaken for a primary<unk> -cell tumor of bone — the latter entity can behave as a neoplasm of benign, frankly malignant, or borderline in its clinical behavior.
Giant-cell carcinoma of the lung
Mucinous cystadenocarcinoma of the lung
Sarcomatoid carcinoma of the lung
Epithelial-myoepithelial carcinoma of the lung
Pulmonary sclerosing pneumocytoma
Adenocarcinoma of the lung
Salivary gland–like carcinoma of the lung
Mesothelioma