What is the main histological characteristic of adenocarcinoma?

The main histological characteristic of adenocarcinoma is the formation of glandular structures. Adenocarcinomas are a type of carcinoma that originates in glandular tissue, which is responsible for secretion. In terms of histological appearance, these tumors often display a characteristic pattern of forming ducts or gland-like structures when viewed under a microscope.

The gland formation can vary in complexity, with some adenocarcinomas appearing well-differentiated, where the glands resemble normal tissue, and others appearing poorly differentiated, where the glandular architecture is disrupted and less recognizable. This formation is a key differentiator of adenocarcinoma from other types of tumors, as it reflects the origin from glandular epithelium.

While the other histological features like spindle-shaped cells, signet-ring cells, and high levels of mitotic figures can be seen in various forms of neoplasia or particular subtypes of cancers, they do not specifically define adenocarcinoma as clearly as the presence of glandular structures does. The presence of spindle-shaped cells is typically associated with sarcomas rather than carcinomas. Signet-ring cells are a distinct feature of certain types of adenocarcinomas, especially gastric, but are not a defining