Intraocular Lymphoma: Update on Diagnosis and Management

Chi-Chao Chan, MD; Dana J. Wallace, BS

Disclosures

Cancer Control. 2004;11(5) 

In This Article

Diagnosis

PIOL commonly presents in older patients as a chronic uveitis masquerade syndrome that is unresponsive to therapy with corticosteroids. Patients often complain of blurred vision and floaters.[8,12,14,15] Less common complaints include red eye, photophobia, and ocular pain.[16,17,18] PIOL is one of a group of disorders that can present as intraocular inflammatory processes but are actually malignant diseases.[2,13,19] Thus, the inflammation seen on clinical examination in these patients is a result of inflammation secondary to a primary disorder or represents noninflammatory cells and opacities.

Visual acuity is often better than would be expected based on the clinical examination.[12] The most common finding on ocular examination is vitreitis. The posterior segment examination usually reveals vitreous cells, which may form clumps or sheets.[8,12,16,20,21] Between 50% to 75% of patients present with cells in the anterior chamber.[8,22,23] In addition, examination of the fundus often reveals large, multifocal, cream- or yellow-colored subretinal infiltrates (Figure 1). If these lesions resolve, retinal pigment epithelium (RPE) atrophy and subretinal fibrosis may be evident as well.[24]

Fundus photograph of a patient with PIOL showing yellow subretinal infiltrates that appear slightly hazy due to an overlying vitreitis.

Several groups have studied angiographic findings in PIOL. In a series of 44 patients, Cassoux et al[25] found punctate hyperfluorescent window defects in 54.5%, round hypofluorescent lesions in 34%, and vasculitis in 13.6%. At the National Eye Institute, a study of 17 patients with PIOL revealed that the most common findings were granularity, late staining, and blockage at the level of the RPE (Figure 2). Notably lacking were perivascular staining or leakage, macular edema, and other angiographic signs of inflammation.[18]

Fluorescein angiogram of a patient with PIOL showing blockage that corresponds to tumor infiltrates.

Ultrasound may also be helpful in narrowing the diagnosis. Ultrasonographic findings in 13 patients with ocular lymphoma included vitreous debris (77%), choroidal-scleral thickening (46%), widening of the optic nerve (31%), elevated chorioretinal lesions (23%), and retinal detachment (15%).[26]

Patients with CNS involvement may also present with general or focal neurological signs and symptoms. A review by Herrlinger et al[27] found that the most common general symptoms were due to increased intracranial pressure (headache, nausea), seizures, and behavioral changes. The most common focal findings were hemiparesis, ataxia, and cranial nerve palsies.

Given the nonspecific nature of eye findings in PIOL, patients being considered for this diagnosis should be examined for other causes of uveitis, including sarcoidosis, intermediate uveitis, multifocal choroiditis, acute posterior multifocal placoid pigment epitheliopathy, birdshot chorioretinopathy, toxoplasmosis, ocular tuberculosis, and acute retinal necrosis.

A thorough medical and neurological examination is important, including a chest radiograph, complete blood cell count, erythrocyte sedimentation rate, routine blood chemistries, and other laboratory studies to exclude the aforementioned causes of uveitis. Because PIOL is closely related to PCNSL and seldom involves other organs, neuroimaging of the brain and orbits and a lumbar puncture are required.[3,28,29] Computed topography (CT) scans usually reveal isodense or hyperdense lesions. Magnetic resonance imaging studies usually reveal lesions that are hypo-dense on T1-weighted and hyperdense on T2-weighted images.[11] Lesions are single at diagnosis in up to 70% of cases but are usually multifocal in late stages (Figure 3). The site of origin usually lies in the basal ganglia, corpus callosum, or periventricular subependymal regions.[30] While imaging studies play an important role in the diagnosis of PCNSL, their role in the diagnosis of PIOL is more limited. Ocular imaging studies of 7 patients with biopsy-proven PIOL revealed ocular findings in only 4 of the patients on T1-weighted CT and magnetic resonance images after contrast injection. Furthermore, these imaging modalities were not able to distinguish ocular lymphoma from other diseases such as uveitis or ocular melanoma.[31]

Brain magnetic resonance imaging of a patient with PIOL showing multiple contrast-enhancing lesions (arrows).

Cerebrospinal fluid (CSF) should be sent for routine cytologic, chemical, and cytokine analysis. Lymphoma cells can be identified in the CSF of 25% of patients with known lesions on magnetic resonance imaging.[32] If lymphoma cells are found in the CSF, then a diagnosis of PCNSL can be made and no further diagnostic procedures are necessary to obtain an intraocular biopsy in a suspected eye. However, even if lymphoma cells are not found in the CSF, a stereotactic brain biopsy should be considered for patients who have suspicious brain lesions on neuroimaging studies.[33] For patients with no evidence of disease by neuroimaging or CSF, a diagnostic vitrectomy should be performed on the eye with more severe vitreitis or worse visual acuity.[21]

Cytology and Pathology. Diagnostic vitrectomy is the most common surgical procedure used to confirm a clinical impression of PIOL. Vitreous specimens should be handled with care to protect the often fragile lymphoma cells. The undiluted sample should be placed in 3 to 5 mL of cell culture medium and immediately brought to the cytology laboratory for rapid processing.[12,34]

Vitreous aspiration needle tap may also be used for diagnostic purposes. An advantage in this technique is that is can be completed in an outpatient setting without the need for monitored anesthesia. Lobo and Lightman[35] recently reported 26 patients with suspected PIOL, 8 of whom were confirmed to have primary B- or T-cell intraocular lymphoma by this procedure. Two of these 8 patients required retinal biopsies in addition to the tap to confirm diagnosis, 1 of whom had been treated with cyclosporine and oral prednisolone for 2 months prior to the tap. The remaining 18 patients were found to have infectious uveitis or nonspecific chronic inflammatory cells. The only complication noted in this procedure was a retinal detachment in one eye that developed 3 months after the procedure. Thus, this procedure may serve as a simpler mechanism to differentiate between infectious, malignant, and inflammatory causes of uveitis.

Malignant lymphoma cells found in vitreous fluid and CSF are usually large and pleomorphic with scanty basophilic cytoplasm (Figure 4).[2,34] Other typical findings include hypersegmented round, oval, bean, or clover shaped nuclei with prominent nucleoli and multiple mitoses.[12] However, the identification of malignant cells in vitrectomy samples is confounded by the presence of reactive immune cells, necrotic cells, debris, and fibrin. While CSF samples have less necrotic debris, they usually have few malignant cells.[12,29]

Typical cytology of PIOL cells from the vitreous showing several atypical lymphoid cells with basophilic cytoplasm and large prominent irregular nuclei.

When attempts to obtain a vitrectomy specimen have been unsuccessful or no cells are evident in the specimen, chorioretinal biopsies may be considered.[36] Chorioretinal biopsies can reveal a tumor cell infiltrate between the RPE and Bruch's membrane (Figure 5), perivascular clumps of tumor cells in the retina and optic nerve head, diffuse infiltration in the vitreous, and hemorrhagic retinal necrosis. Chorioretinal biopsies may also reveal areas of retinal depigmentation, atrophy, and scarring due to RPE detachment and choroidal reactive lymphocytic infiltration.[29,37] Fine-needle aspiration biopsy has been used in lieu of full thickness chorioretinal biopsy when vitrectomy was non-diagnostic. Lesions selected for this technique should be 1.5 mm or greater in height in order to prevent choroidal penetration. This technique has an advantage over vitrectomy by providing increased concentration of viable cells for cytopathologic diagnosis and molecular studies.[38,39]

Histological examination of the eye showing tumor cells located between Bruch's membrane and the RPE (arrow). The tumor cells have penetrated the RPE and are infiltrating towards the retina (R, retina; C, choroids; hematoxylin and eosin, x 400).

Because of the varying presentation of PIOL, diagnosis is often delayed 10 to 21 months, after a mean of 4.3 diagnostic procedures.[8,12,15] Mishandling of vitreous specimens and prior treatment with corticosteroids at the time of vitrectomy, which are known to be cytolytic to lymphoma cells,[12] can lower the diagnostic yield. A series of 12 cases at the National Eye Institute revealed that 30% of PIOL patients had previous false-negative biopsy specimens.[12] When diagnostic vitreous aspiration, vitrectomy, needle biopsy, and chorioretinal biopsy have failed, diagnostic enucleation of a blinded eye could be considered.[40,41]

It is difficult to arrive at a pathologic diagnosis of [33,42] Thus, research has been focused on developing other methods to assist in the diagnosis of PIOL. These methods include immunohistochemistry, flow cytometry, molecular analysis, and cytokine evaluation.

Immunophenotyping and Flow Cytometry. Immunohistochemistry and flow cytometry rely on the finding that most PIOLs are monoclonal populations of B lymphocytes that stain for B-cell markers (CD19, CD20, CD22) and have restricted expression of kappa or lambda [12,34,40] Immunohistochemistry has also been used to demonstrate expression of BCL-6 and MUM1 in PIOL cells. BCL-6 is a B-cell marker that is normally turned off as B cells move from the germinal center into the marginal zone during B-cell differentiation.[43] MUM1 is a protein involved in the control of plasma cell differentiation. While B cells usually express only one of these proteins at a time, concomitant expression of these proteins has been shown in systemic diffuse large B-cell lymphoma.[44] Similar patterns of expression have also been demonstrated in 5 patients with PIOL.[45]

Several studies have demonstrated that flow cytometry may be a helpful addition in the diagnosis of PIOL. Flow cytometry allows for the analysis of several different markers simultaneously and has been used to confirm monoclonality in PIOL. Immunophenotyping by flow cytometry was found to be diagnostic of PIOL in 6 of 10 patients, whereas cytology was positive in only 7 of 12 patients.[15] In addition, flow cytometry identified intraocular lymphoma in 7 of 10 patients compared with only 3 diagnosed by cytology.[46] However, other studies have found cytologic evaluation to be more accurate.[42] It is still believed that a pathologic diagnosis is required to confirm the presence of PIOL and that immunophenotyping plays a supportive role in diagnosis.

Molecular Analysis. Microdissection and polymerase chain reaction have become useful adjuncts in the diagnosis of PIOL. These techniques allow for selection of a relatively pure cell population from frozen or paraffin-embed-ded archival tissues.[47] Studies of systemic non-Hodgkin's lymphomas have revealed amplification of rearranged heavy chain immunoglobulin (IgH) gene sequences, particularly in the third complementarity-determining region (CDR3) of the IgH variable region.[48,49] Likewise, ocular specimens from patients with PIOL have revealed similar IgH rearrangements that can serve as a molecular marker of clonal expansion of lymphocytes.[47] Using primers in microdissection and PCR studies, it was found that in 57 PIOL samples, 100% expressed the IgH gene rearrangement at the CDR3 site.[50] Monoclonality of B-cell populations has also been characterized with the use of FR3, FR2, and CDR3 primers and polymorphism analysis.[47,51]

Microdissection and PCR analysis have also been used to examine the expression of a translocation between the genes for IgH and Bcl-2. Bcl-2,a gene involved in the regulation of apoptosis, is located on chromosome 18, while IgH is located on chromosome 14.[52] The t(14;18) translocation brings the Bcl-2 gene under the control of the IgH promoter, thus deregulating the Bcl-2 gene and resulting in Bcl-2 expression.[53] This translocation is found in 85% of follicular non-Hodgkin's lymphomas and 28% of diffuse large B-cell lymphomas.[54,55] Sixty percent of Bcl-2 breakpoints are located at the major breakpoint region (mbr) in the 3' non-coding part of the third exon. The next most frequent location for translocations (10% to 25%) is the minor cluster region (mcr) located 20 kb downstream of the gene.[55,56,57]

Analyses performed on specimens from 69 patients with PIOL revealed that 37 (54%) expressed the t(14;18) translocation at the mbr.[47] We have recently detected that 15 (22%) of 68 patients with PIOL express the translocation at the mcr in addition to the translocation at the mbr (D.J.W., unpublished data, 2004). Of these patients, 14 (93%) of 15 were also positive for the mbr, indicating some overlap of the breakpoint regions, while 1 (7%) was positive only at the mcr. While the t(14;18) translocation is used as a marker for diagnosis and monitoring of follicular lymphoma, its role in prognosis and treatment selection for follicular lymphoma and diffuse large B-cell lymphoma remains unclear and is being investigated in clinical stud-[58,59,60,61,62] Likewise, it will be important to determine the role of Bcl-2 expression in clinical presentation, treatment response, relapse rate, and survival in patients with PIOL.

Cytokines. Cytokines may play a role in distinguishing PIOL from uveitis. While interleukin 6 (IL-6) is produced in high levels by inflammatory cells in uveitis, IL-10 is produced by malignant B lymphocytes in intraocular and CNS lymphoma.[63] Moreover, PIOL is strongly associated with an increased IL-10 to IL-6 ratio (greater than 1.0).[63,64,65] This is supported by findings of 35 patients with PIOL and 64 patients with infectious and noninfectious uveitis where the 1.0 cutoff rule was correct 74.7% of the time (sensitivity 74.3%, specificity 75.0%).[66] There have been previous reports of 2 patients with cytologically proven intraocular CNS lymphoma with a vitreous IL-10 to Il-6 ratio less than 1.0.[37,67] However, one of these cases represented early-stage disease.[37]

Lymphoma cells express chemokine receptors selective for B cells such as CXCR4 and CXCR5. The RPE of involved eyes expresses the ligands for these receptors, SDF-1 (CXCL12) and BLC (CXCL13), respectively, thus suggesting a pathogenetic role for B-cell chemokines in the homing of lymphoma cells to the RPE.[68]

A diagnosis of PIOL should be considered for a patient older than 35 years of age with a history of posterior uveitis with the presence of vitreous cells in sheets and clumps on funduscopic examination or retinal lesions by fluorescein angiography. These patients should undergo neuroradiologic imaging and CSF examination. No further ocular diagnostic tests are required in patients with positive CSF. In patients with negative CSF, a vitrectomy or vitreous tap should be performed in the eye with more severe vitreitis or worse visual acuity. This sample should be carefully sent for cytology, cytokine analysis, IgH rearrangements, Bcl-2/IgH translocations, and immunohis-tochemistry/flow cytometry. Chorioretinal biopsies may be required when vitrectomy specimens are nondiagnostic. Figure 6 summarizes the diagnostic guideline used at the National Eye Institute. Since systemic symptoms are usually present at the time of diagnosis for patients with systemic lymphoma involving the eye, systemic evaluation, CT scans of the chest and abdomen, and bone marrow aspirate and biopsy are not usually performed unless systemic symptoms are present.[69] Because of the cytolytic nature of corticosteroids on lymphoma cells, corticosteroid treatment should be withheld until all diagnostic procedures are completed.

Algorithm for the diagnosis of PIOL.

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