Microcystic

Microcystic is a descriptive term used in pathology and medicine to refer to tissue architecture that contains numerous small cyst-like spaces. The word combines micro- (small) with cystic (cyst-like) and is not a disease on its own; rather, it characterizes a pattern observed in various conditions.

In histology, microcystic patterns may appear in both benign and malignant processes across different organs. The spaces are typically microscopic and may represent true cysts or dilated ducts or acini. They are often lined by epithelial cells and can contain clear, proteinaceous, or other fluid contents. The surrounding stroma may be fibrous, edematous, or otherwise altered by the underlying process.

Representative contexts include microcystic serous cystadenoma of the pancreas, a benign neoplasm characterized by many small cysts; microcystic adenosis of the breast, a benign lesion with ductal microcysts; and microcystic adnexal carcinoma, a rare malignant skin tumor with infiltrative growth and duct-like microcystic structures. The term is also used more broadly to describe similar microcystic patterns within other tumors or inflammatory conditions.

Diagnosis relies on histopathologic evaluation supplemented by clinical information and, when appropriate, immunohistochemistry and imaging studies. Microcystic notation serves as a descriptive aid to understanding a lesion’s architecture, guiding differential diagnosis and influencing interpretation in concert with overall morphology and context.