In some institutions, vitrectomy samples are processed routinely. The ophthalmic pathologist can provide the following types of feedback from the routine study of vitrectomy specimens:
- Identification of unsuspected retinal tissue.
- Identification of internal limiting membrane from procedures involving stripping of epiretinal membranes
- Identification of iron (toxic to the retina) in cases of long-standing vitreous hemorrhage
- Identification of hypertrophic retinal pigment epithleial cells in cases of retinal detachment repair, perhaps suggesting early proliferative vitreoretinopathy
- Unexpected substances in the vitreous such as amyloid
- Identification of organisms
Note the pseudophypha in this vitrectomy sample from a patient with suspected Candida endophthalmitis.
Vitreoretinal surgeons may also request that samples be sent to the pathology laboratory. The most common indication for the specific examination of vitreous material is to rule out retinal lymphoma.
The ophthalmologist should keep the following points in mind when planning for an intraocular biopsy to rule out retinal lymphoma:
- In patients with systemic lymphoma, the uvea is usually infiltrated. In patients with CNS lymphoma, the retina and sub-RPE compartments are usually infiltrated and the uvea may be thickened by an infiltrate of benign lymphocytes. By aspirating vitreous, the surgeon is attempting to collect cells that have spilled over from the neurosensory retina.
- Therefore, it is best if the surgeon tries to aspirate directly over a lesion rather than sample from the center of the vitreous.
- It is best to obtain a direct aspirate before beginning to use the vitrectomy instrument. There are several reasons for this:
The vitrectomy instrument cuts, aspirates, and infuses balanced saline. The mechanical action of cutting and aspiration may lyse neoplastic lymphocytes, and exposure to balanced saline may also damange neoplastic lymphocytes.
- Please alert the pathology laboratory before beginning the procedure. It is best if a technician is present in the operating room to receive the direct aspirate sample. The vitrectomy collection container should also be submitted, but the quality of cytology may not be as good as the material aspirated directly.
- The pathology laboratory can assess the morphology of the vitreous infiltrate, and immunocytochemistry can be performed on prepared slides. If sufficient quantities of cells are available, it is possible to perform flow cytometry on these samples.
Large quantities of vitreous fluid containing visible particles may be processed by cell block.
Specimens submitted for possible retinal lymphoma may be processed by cytospin to allow for better cellular preservation.
The PAS stain may be helpful in identifying basement membrane structures, such as the internal limiting membrane.
Primary retinal lymphoma is usually a large cell lymphoma, B-cell type.
If you have more questions about vitrectomy specimens, please contact one of us:
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