William Osler, the famous Canadian, wrote “As is our pathology, so is our practice.” This statement holds for ophthalmology. Ophthalmic pathology provides the link between basic science, clinical medicine and the pathologic process which the grammar of medicine translates into the clinical ocular disease that we encounter daily.
The eye is a unique organ because it is composed of varied histologic structures. The orbit is similar to Pandora's Box. A multitude of lesions present in the orbit that may puzzle even an expert clinician and an experienced pathologist by virtue of the wide range of presentation. Unlike other structures in the body, lesions in many parts of the eye are easily visible to the patient and the clinician. Even small intraocular lesions are associated with pain, photophobia, distortion or loss of vision, leading the patient to seek early ophthalmic consultation.
Management of ocular disease has been enhanced with the use of various magnifying instruments such as slit lamps, ophthalmoscopes, diagnostic lenses, thus enabling detailed examinations of the eye and adnexa. Microsurgical techniques and advancement of surgical instruments allow removal of minute amounts of ocular tissue and membranes over the retina despite difficult access. Ophthalmologists can now take imprints from the conjunctival specimens, aspirate fluid or obtain tissue from the anterior chamber, vitreous cavity, subretinal space, or an orbital lesion and study the tissue using histopathology.1
Ophthalmic biopsy specimens are often quite small and require immense care in handling and processing. Prior to processing, the pathologist reviews the patient's clinical history with relevant ophthalmic findings and the clinical impression. After appropriate evaluation by employing relevant tests and techniques, the pathologist is able to provide a more holistic opinion on the diagnosis.
Similar to general pathology, ophthalmic pathology utilizes routine stains such as hematoxylin and eosin and other more specialized stains as the case warrants. This issue contains three articles that will further our understanding of the application of ophthalmic pathology.
Uveitis can be diagnosed from clinical examination, and ancillary tests such as fluorescein angiography, indocyanine green angiography and ultrasonography. However, speculation on etiology can occur for recalcitrant uveitis, atypical clinical scenarios and masquerade syndromes such as intraocular lymphoma. Histopathologic study and definition of cell types is the single most definitive element in an evaluation where attributes are deduced with regard to biological behavior of the tumor and prognosis. These articles describe the spectrum of techniques such as anterior chamber tap, methods of obtaining vitreous sample, retinochoroidal biopsy and the role of simple microscopy and molecular biologic techniques such as polymerase chain reaction to enhance the diagnosis.
A single clinical expression may be present in various corneal diseases, and staining techniques aid in establishing the diagnosis with certainty. Corneal infection is an important cause of ocular morbidity worldwide, particularly in developing countries. The article by Vemuganti et al, describes various histopathologic changes associated with corneal infection and inflammation. Several distinguishing features between bacteria, virus, acanthamoeba, nocardia and mycobacteria exist which may not be detectable clinically but can be resolved by pathological evaluation.
Another intrinsic merit of biopsy and histopathologic study is in the diagnosis of orbital infection and inflammation which, though less common than corneal diseases and uveitis, is as challenging. The article by Vincent et al, describes bacterial, fungus and parasitic infections as well as non-infectious orbital inflammation. Pathologic study plays an important role in the precise identification of such inflammation and infection.2
New technologies have emerged and contributed to the diagnosis of infectious agents, particularly polymerase chain reaction which can now be done from paraffin sections as well. Immunohistochemistry has become the mainstay for the diagnosis of non-Hodgkin's lymphomas (NHLs), childhood tumors such as rhabdomyosarcoma and undifferentiated tumors.
A timely biopsy, staining or histopathologic analysis can help provide a precise diagnosis or may complement the existing diagnosis, ensuring the optimum treatment modalities or management based on stage and type of lesion. Advancements in diagnostic pathology, immunohistochemistry and molecular biology have significantly benefited both the clinician and the patient.
A high degree of concordance with clinical suspicion may help in confirmation of the diagnosis. However, it is of tremendous help when the etiology cannot be established or in addressing the management more efficiently. The main advantage is in establishing diagnosis that is diametrically opposite to the suspected etiology and clinical impression, and it is in such situations that pathology is undisputedly most relevant.
REFERENCES
- 1.Biswas J, Krishna Kumar S, Shweta A. India: Jaypee – Highlights Medical Publishers; 2010. Manual of Ocular Pathology. [Google Scholar]
- 2.Holds JB. Section. San Francisco: American Academy of Ophthalmology; 2007-2008. Infectious and inflammatory disorders. Basic and Clinical Sciences Course. Section 7. Orbit, Eyelids, and Lacrimal system; p. 39. [Google Scholar]
