The embedding histologist must practice developing rapid visual recognition of tissue types and be able to determine the correct orientation for each specimen using his or her knowledge of anatomy and tissue sampling techniques. It is often helpful to consider the reason(s) that each specimen may have been selected for submission to histology. The ultimate goal for each specimen submitted is to arrive at a diagnosis based on the type of specimen and the suspected reason for the surgical procedure performed.
Gross dissection of tissue samples is determined by a pathologist or pathologist's assistant (PA). Many laboratories follow established protocols for the gross dissection of particular types and categories of specimens. These protocols often influence and determine the number of tissue cassettes submitted per specimen.
Specimens are identified using a numbering system that associates a unique number with a specific patient, medical record number, and tissue sample upon receipt. The tissue cassette containing the specimen from that specific patient and procedure is also identified with the same unique number. This unique number is transcribed on the slanted top edge of the tissue cassette by either hand or an automated printer, as shown in the image below. Cassettes can also be printed with 3D barcodes, which are scanned at embedding to provide the embedder with the pertinent details of how the specimen was submitted. The slides prepared from the paraffin-embedded block (from this cassette) in the histology laboratory are likewise identified with this unique number, as shown in the image on the right.
Tissue is selected for microscopic examination to document important details about each specimen. Some examples of specimens that may be selected for submission to histology include:
- All lesions grossly identified - Tissue between lesions may be included with the lesion to determine if the lesion is separate or interconnected to surrounding normal tissue.
- Representative sections of all normal tissues or structures that are not included with suspected disease-containing sections.
- All surgical margins, when appropriate.
- Frozen-section remnants for permanent sections.
