Epitheloid

Epithelioid refers to a cellular morphology resembling epithelial cells, typically characterized by abundant pale cytoplasm, indistinct cell borders, and vesicular or oval nuclei. This appearance is not specific to a particular tissue type but is rather a descriptive term used in histology and pathology to denote a particular cellular shape and arrangement. Cells that appear epithelioid are often found in a variety of conditions, including inflammatory processes, granulomas, and tumors.

In inflammatory reactions, epithelioid cells are often seen in chronic inflammation and granulomatous diseases, such as tuberculosis, sarcoidosis, and Crohn's disease. They are believed to arise from activated macrophages that have differentiated into this specific morphology in response to persistent antigens or foreign bodies. These cells can aggregate to form granulomas, which are organized collections of inflammatory cells.

In the context of tumors, epithelioid morphology can be observed in a wide range of neoplasms, both benign and malignant. For example, epithelioid leiomyomas are benign smooth muscle tumors, while epithelioid sarcomas are aggressive malignant mesenchymal tumors. Epithelioid cells in tumors can also arise from various cell lineages, including epithelial cells, mesenchymal cells, and even lymphoid cells, depending on the tumor type. The interpretation of epithelioid morphology in a tumor often requires correlation with other histological features, immunohistochemical staining, and clinical information to determine the precise diagnosis and origin of the neoplasm.