What is a neoplasm that is a malignancy composed of the epithelial tissue of a gland called?

The term for a malignancy that originates from the epithelial tissue of a gland is adenocarcinoma. This type of cancer arises specifically in glandular tissues, which can include various organs such as the pancreas, breast, prostate, and colon, among others. Adenocarcinoma is characterized by the formation of glandular structures or by the production of mucin, which is a key feature distinguishing it from other malignancies.

Carcinomas, in general, are cancers that arise from epithelial cells, but they are a broader category that includes many different types of epithelial cancers beyond just glandular tissues. Sarcomas originate from connective tissues such as muscle, fat, or bone, making them fundamentally different from adenocarcinomas. Lymphomas, on the other hand, are malignancies of the lymphatic system and do not arise from epithelial tissues at all. Therefore, adenocarcinoma is the most precise and correct term to use for a malignancy that specifically involves the epithelial tissue of glands.