Contributor: Gordon K. Klintworth
A chalazion is a common lesion of the eyelid composed of a mixed cellular infiltrate of  polymorphonuclear leukocytes, lymphocytes, plasma cells, macrophages and epithelioid cells. Multinucleated giant cells are common. The differential diagnosis of a chalazion includes sebaceous carcinoma and conditions that cause granulomatous inflammation (including sarcoidosis, tuberculosis and fungal infections). The most important condition to differentiate from a chalazion is sebaceous carcinoma of the eyelid, which can mimic chalazia clinically and can even be associated with contiguous chronic granulomatosis inflammation.