CHAPTER 3
Specimen Handling
Communication
Communication with the pathologist before, during, and after surgical procedures is an essential aspect of quality patient care. Standards for the technical handling of specimens and reporting of results have been developed and are available on the website of the College of American Pathologists (www.cap.org). The final histologic diagnosis reflects successful collaborative work between clinician and pathologist. The ophthalmologist should provide a relevant and reasonably detailed clinical history when the specimen is submitted to the laboratory. This history facilitates clinicopathologic correlation and enables the pathologist to provide the most accurate interpretation of the specimen.
Where there is an ongoing relationship between a pathologist and an ophthalmologist, communication usually can be accomplished through the pathology request form and the pathology report. However, if a malignancy is suspected or if the biopsy will be used to establish a critical diagnosis, direct and personal communication between the ophthalmic surgeon and the pathologist can be essential. This preoperative consultation allows the surgeon and pathologist to discuss the best way to submit a specimen. For example, the pathologist may wish to have fresh tissue for immunohistochemical stains and molecular diagnostic studies, glutaraldehyde-fixed tissue for electron microscopy, and formalin-fixed tissue for routine paraffin embedding. If the tissue is simply submitted in formalin, the opportunity for a definitive diagnosis may be lost. Communication between clinician and pathologist is especially important in ophthalmic pathology, where specimens are often very small and require very careful handling. In some cases, careful selection of the surgical facility is necessary to ensure proper specimen handling. Biopsies may be incisional, in which only a portion of the tumor is sampled, or excisional, in which the entire lesion is removed. See BCSC Section 7,
Orbit, Eyelids, and Lacrimal System, for further discussion.
Any time a previous biopsy has been performed at the site of the present pathology, the sections of the previous biopsy should be requested and reviewed with the pathologist who will interpret the second biopsy. The surgical plan may be altered substantially if the initial biopsy was thought to represent, for example, a basal cell carcinoma when in fact the disease was a sebaceous carcinoma. In addition, the pathologist will be able to interpret intraoperative frozen sections more accurately when the case has been reviewed in advance.
If substantial disagreement arises between the clinical diagnosis and the histologic diagnosis, the ophthalmologist should contact the pathologist directly and promptly to resolve the discrepancy. Mislabeling of pathology specimens or reports through a simple typing error, for example, can have serious consequences. Merely correcting the patient age on the pathology request form may change the interpretation of melanotic lesions of the conjunctiva. Benign melanotic lesions in children may have a histologic appearance similar to that of malignant melanotic lesions in adults. Whether the patient is age 4 or age 44 makes a tremendous difference in interpretation.
Orientation
Globes may be oriented according to the location of the extraocular muscles and of the long posterior ciliary arteries and nerves, which are located in the horizontal meridian. The medial, inferior, lateral, and superior rectus muscles insert progressively farther from the limbus. Locating the insertion of the inferior oblique muscle is very helpful in distinguishing between a right and a left eye (Fig 3-1). The inferior oblique inserts temporally over the macula, with its fibers running inferiorly. Once the laterality of the eye is determined, the globe may be transilluminated and dissected.
Transillumination
Eyes are transilluminated with bright light prior to gross dissection. This helps to identify intraocular lesions such as a tumor that blocks the transilluminated light and casts a shadow (Fig 3-2A). The shadow can be outlined with a marking pencil on the sclera (Fig 3-2B). This outline can then be used to guide the gross dissection of the globe so that the center of the section will include the maximum extent of the area of interest (Figs 3-2C to 3-2E).
Figure 3-1 Posterior view of right globe. N = nasal, T = temporal. (Modified by C.H. Wooley from an illustration by Thomas A. Weingeist,
PhD, MD.)
Figure 3-2 Preparation of an intraocular tumor specimen. A, Transillumination shows blockage to light secondary to an intraocular tumor. B, The area of blockage to light is marked with a marking pencil. C, The opened eye shows the intraocular tumor that was demonstrated by transillumination. D, The paraffin-embedded eye shows the intraocular tumor. E, The H&E- stained section shows that the maximum extent of the tumor demonstrated by transillumination is in the center of the section, which includes the pupil and optic nerve. (Courtesy of Hans E. Grossniklaus, MD.)
Gross Dissection
A globe is opened so as to display as much of the pathologic change as possible on a single slide. The majority of eyes are cut so that the pupil and optic nerve are present in the same section, the PO section. The meridian, or clock-hour, of the section is determined by the unique features of the case, such as the presence of an intraocular tumor or a history of previous surgery or trauma. In routine cases, with no prior surgery or intraocular neoplasm, most eyes are opened in the horizontal meridian, which includes the macula in the same section as the pupil and optic nerve (Fig 3-3). Globes with a surgical or nonsurgical wound should be opened so the wound will be perpendicular to, and included in, the PO section, which often means opening the globe vertically. Globes with intraocular
tumors are opened in a way (horizontal, vertical, or oblique) that places the center of the tumor as outlined by transillumination in the PO section.