Anatomic pathology is the branch of pathology that is concerned with the diagnosis of disease based on the gross and microscopic examination of cells and tissues. The father of the modern Anatomical pathology is the Italian Giovanni Battista Morgagni.

Anatomic Pathology (AP) is one of the two primary certifications offered by the American Board of Pathology. The other is Clinical Pathology (CP).

Role of the anatomic pathologist

Contrary to popular belief, the field mostly concerns the study of tissue obtained from live patients. In fact, almost all tissues removed from a patient for any reason are examined by a pathologist. The autopsy, though, remains an important tool in gaining medical knowledge.

Biopsy specimens are small pieces of tissue. Biopsy of a tumor is helpful when its nature is uncertain. Histological examination of the tumor biopsy usually allows the pathologist to determine if the tumor is benign or malignant, and differentiate between different types of cancer. This information is important for accurate estimation of the prognosis and choice of the best therapy. Biopsies can also be used to diagnose diseases other than cancer. For example, the dermatopathologist sees many skin biopsies from rashes and other inflammatory skin diseases, taken by dermatologists when the nature of the disease is not evident. Stomach and colon biopsies are also taken to help diagnose inflammatory or infectious diseases of the digestive tract.

In contrast to a biopsy that merely samples a lesion, an excision (or resection) specimen is the complete removal of the tumor or diseased organ by a surgeon. For example, a mastectomy specimen contains the whole breast tissue, overlying skin and adjacent lymph nodes. On excision specimens, the pathologist will comment on surgical margins to estimate the likelihood that the tumor was completely excised during the surgery.

The opinion of the pathologist is written as a pathology report addressed to the doctor who performed the procedure.