Forensic Pathology for Police - Brainshare Public Online Library

Introduction to Pathology 7
Fig. 1.2 A blood smear, as seen via a microscope. The round cells with no nuclei are red blood
cells. The slightly larger cells with nuclei are white blood cells, including a neutrophil on the left
and a lymphocyte on the right. The small structures are platelets
Anatomic pathology is the second of the two major branches within the medical
specialty of pathology. The term “anatomic” refers specifically to the structure (or
“morphology”) of tissues and organs. Chapter 6 provides an overview of normal
anatomy. Pathologists, in their role as anatomic pathologists, deal with recognizing
and diagnosing abnormal, or diseased anatomy. A tissue or organ that is afflicted
with a disease undergoes various changes, such that its gross (naked-eye) appearance,
microscopic (histologic) appearance, and function are altered. Pathologists
rely on the gross and microscopic appearance of diseased tissues, as well as various
other laboratory tests, to render diagnoses. There are three basic components within
anatomic pathology: surgical pathology, cytology (also called cytopathology), and
autopsy pathology.
Surgical pathology involves the gross and microscopic evaluation of tissues
removed by surgical means. Whenever a person has a surgical biopsy performed, or
an organ removed via surgery, the removed tissue is sent to the surgical pathology
laboratory, where, after the specimen has become “fixed” in formalin (a preservative
solution containing formaldehyde), pathologists or their assistants dissect the
specimen (Fig. 1.3 and Disc Images 1.3 and 1.4) and submit samples of the tissue
(Fig. 1.4) to the “histology laboratory.” Here the samples are “processed” by histotechnologists
via a procedure utilizing various chemicals (Fig. 1.5), such that the
samples end up embedded in paraffin wax (Figs. 1.6 and 1.7). The histotechnologists
then cut extremely thin sections of the tissues (Fig. 1.8), place the sections on
glass slides (Fig. 1.9), and stain them for viewing under the microscope. The usual
stain that is used for histologic examination is hematoxylin and eosin (referred to
as an H&E stain) although there are numerous other “special stains” that can be
utilized. The pathologist views the glass slides via the microscope (Fig. 1.10) and
renders diagnoses, based on the microscopic anatomy that is seen (Figs. 1.11, 1.12,
1.13, 1.14 and Disc Image 1.5). The microscope allows pathologists to visualize the
tissues and cells at various magnification powers. By evaluating tissue specimens