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Primary intraocular lymphoma (PIOL) is a high grade malignant non-Hodgkin’s lymphoma (NHL) usually of B cell type, involving the retina and vitreous. PIOL can occur independently or together with primary central nervous system lymphoma (PCNSL; the combination termed “oculocerebral lymphoma”). Because of its slow onset and ability to simulate other conditions, the diagnosis of PIOL remains challenging. A number of techniques, including conventional cytology, immunocytology, flow cytometry, polymerase chain reaction (PCR), and biochemical analysis of vitreous samples, are recommended to aid the diagnostic procedure.1–8 We report a case of oculocerebral lymphoma, whereby IgH-PCR and GeneScan analysis confirmed the histological diagnosis by demonstration of the identical clonal B cell populations in both the vitreous and stereotactic biopsy.
A 51 year old systemically healthy man presented in March 2002 with an epileptic fit. Cranial magnetic resonance imaging demonstrated a mass with intensive contrast enhancement in the left fronto-parietal area. A stereotactic biopsy was performed, establishing the diagnosis of a high grade malignant B cell NHL (fig 1A). The neoplastic cells consisted of medium to large sized blasts and were orientated perivascularly. They demonstrated immunoreactivity for CD20, a monotypical expression of Ig-kappa, and a large growth fraction (Ki-67 antigen) of 90%. Staging procedures did not reveal any systemic lymphoma. Two cycles of high dose methotrexate chemotherapy (4 g/m2 intravenously per cycle) were commenced. The patient developed recurrent epileptic attacks, and repeat imaging studies demonstrated tumour size increase. The patient was treated with whole brain irradiation (total dosage, 45 Gy), resulting in complete remission for 14 months. In August 2003, the patient complained of “floaters” and a bilateral decrease in vision. On examination, the visual acuity (VA) was 20/25 and 20/32 in the right and left eyes, respectively. Funduscopy revealed bilateral dense cellular infiltrates in the vitreous.
Conventional and immunocytological examination of a diagnostic vitrectomy of the left eye disclosed an intraocular manifestation of B cell NHL. The infiltrating atypical lymphocytes (fig 1B) expressed CD20, and displayed a monotypical expression of Ig-kappa. The remaining vitreous aspirate and the paraffin embedded cerebral biopsy material were submitted for clonality analysis using IgH-PCR and GeneScan techniques. For the detection of IgH rearrangements, three single step PCRs were performed employing family specific framework (FR) 1, FR2, and FR3 Bio-Med 2 primers together with a common JH consensus primer (JH22).9 The cycling conditions (50 rounds of amplification) for all PCRs are described in detail elsewhere.9 Both samples revealed dominant PCR products of the same size(FR1 327 base pairs, FR2 257 base pairs, FR3 125 base pairs), demonstrating the identical neoplastic B cell population in both lymphomatous manifestations (fig 2). Further, DNA sequencing of the amplificates revealed a functional VH3/JH4 rearrangement of the tumour cells.
Thorough imaging studies revealed neither a cerebral recurrence nor evidence of systemic lymphoma. The patient was commenced on high dose ifosfamide (1500 mg/m2 intravenously daily over 3 days/cycle). In January 2004, follow up examinations demonstrated a complete resolution of lymphomatous infiltrates in both eyes, and the VA was 20/20 bilaterally.
Cytological studies of vitreous biopsies remain the first step in the histomorphological diagnosis of PIOL. Previous reports have described the use of PCR examining for monoclonal rearrangements of immunoglobulin heavy (IgH) or light (IgL) chains in B cell lymphoma or T cell receptor genes in T cell lymphoma as an adjunctive diagnostic tool in the evaluation of vitreous specimens for PIOL.3–8 The success of these analyses is dependent on the quantity of material provided and the extent of DNA degradation. The quality of DNA extracted from paraffin embedded biopsy material can be compromised by fixation solutions, and the duration of fixation. Improved primers for IgH-PCR and TCR-PCR have recently been developed, thereby increasing the chances of detection of clonal B and T cell populations in tissues and fluids.9 In oculocerebral lymphoma, it is assumed on the basis of clinical, morphological, as well as immunohistochemical findings that the cerebral and ocular infiltrations represent the same tumour. To our knowledge, this association between PIOL and PCNSL has not yet been proved genetically. This case, therefore, represents the first in the literature, whereby molecular biological evidence is provided showing that the lymphomatous manifestations in oculocerebral lymphoma consist of the identical neoplastic B cell population and that they derive from the same tumour precursor cell. Furthermore, DNA sequencing of both specimens demonstrated a similar VH gene usage to that previously reported by PCNSL.10