Protocol for the use of polymerase chain reaction in the detection of intraocular large B-cell lymphoma in ocular samples

Composite lymphoma of peripheral T-cell lymphoma and Hodgkin lymphoma, mixed cellularity type; pathological and molecular analysis

Composite lymphomas (CLs) are defined as two unrelated lymphomas occurring at the same time within the same tissue. The incidence of these tumors is low. Of all possible combinations between lymphomas, the least frequent are the ones combining peripheral T-cell lymphoma (PTCL) and Hodgkin lymphoma (HL). We recently identified five cases of CL composed of PTCL and classical HL, mixed cellularity type. We investigated histological and clinical features of these cases. Immunostaining was performed on paraffin sections. PTCL cells were positive for CD8 and TIA-1 in four of the five cases. Hodgkin and Reed-Sternberg (HRS) cells were positive for CD30 and weakly positive for PAX5 in all cases, positive for CD15 in three of five cases, positive for CD20 in one of five cases, and negative for EBER. Monoclonal rearrangement of the T-cell receptor (TCR) and immunoglobulin heavy chain (IGH) genes was confirmed by polymerase chain reaction (PCR) using whole paraffin sections. We concluded more precisely the monoclonality of the IGH rearrangement of HRS cells based on single-cell PCR for IGH and DNA sequencing analysis after laser microdissection of single cells in one case. HL can occur in CD8-positive and TIA-1-positive PTCL. Clinicians should recognize the possibility of these CL.

Primary intraocular lymphoma

Primary intraocular lymphoma (PIOL) is an ocular malignancy that is a subset of primary central system lymphoma (PCNSL). Approximately one-third of PIOL patients will have concurrent PCNSL at presentation, and 42-92% will develop PCNSL within a mean of 8-29 months. Although rare, the incidence has been rising in both immunocompromised and immunocompetent populations. The majority of PIOL is diffuse large B-cell lymphoma, though rare T-cell variants are described. Recently, PIOL has been classified by main site of involvement in the eye, with vitreoretinal lymphoma as the most common type of ocular lymphoma related to PCNSL. Diagnosis remains challenging for ophthalmologists and pathologists. PIOL can masquerade as noninfectious or infectious uveitis, white dot syndromes, or occasionally as other neoplasms such as metastatic cancers. Laboratory diagnosis by cytology has been much aided by the use of immunocytochemistry, flow cytometry, biochemical finding of interleukin changes (IL10:IL6 ratio > 1), and cellular microdissection with polymerase chain reaction amplification for clonality. Use of several tests improves the diagnostic yield. Approaches to treatment have centered on systemic methotrexate-based chemotherapy, often with cytarabine (Ara-C) and radiotherapy. Use of intravitreal chemotherapy with methotrexate (0.4 mg/0.1 mL) is promising in controlling ocular disease, and intravitreal rituximab (anti-CD20 monoclonal antibody) has also been tried. Despite these advances, prognosis remains poor.

Identification of a functional rare variant in autism using genome-wide screen for monoallelic expression

Recent work has led to the identification of several susceptibility genes for autism spectrum disorder (ASD) and an increased appreciation of the importance of rare and de novo mutations. Some of the mutations may be very hard to detect using current strategies, especially if they are located in regulatory regions. We present a new approach to identify functional mutations that exploit the fact that many rare mutations disrupt the expression of genes from a single parental chromosome. The method incorporates measurement of the relative expression of the two copies of a gene across the genome using single nucleotide polymorphism arrays. Allelic expression has been successfully used to study common regulatory polymorphisms; however, it has not been implemented as a screening tool for rare mutation. We tested the potential of this approach by screening for monoallelic expression in lymphoblastoid cell lines derived from a small ASD cohort. After filtering regions shared across multiple samples, we identified genes showing monoallelic expression in specific ASD samples. Validation by quantitative sequencing demonstrated that the genes (or only part of them) are monoallelic expressed. The genes included both previously suspected risk factors for ASD and novel candidates. In one gene, named autism susceptibility candidate 2 (AUTS2), we identified a rare duplication that is likely to be the cause of monoallelic expression. Our results demonstrate the ability to identify rare regulatory mutations using genome-wide allelic expression screens, capabilities that could be expanded to other diseases, especially those with suspected involvement of rare dominantly acting mutations.

Cytokine and molecular analyses of intraocular lymphoma

PURPOSE

The authors investigate the efficacy of using the cytokine levels and clonal heavy-chain immunoglobulin (IgH) gene rearrangements in the vitreous as adjunctive tools to diagnose intraocular lymphoma (IOL).

METHODS

The IL-10 and IL-6 levels and IgH gene rearrangements were analyzed in vitreous samples from 8 cases of IOL and in 14 uveitis patients.

RESULTS

The level of IL-10 with an IL-10/IL-6 ratio > 1 was significantly higher in all eyes with IOL. B-cell monoclonality was detected in only 5 of 8 eyes with IOL.

CONCLUSIONS

The measurements of the levels of cytokines are valuable as a reliable biomarker.

[Immunophenotyping and gene rearrangement analysis in lymphoid/lymphoproliferative disorders of the lungs]

OBJECTIVE

To determine the usefulness, in routine practice, of using polymerase chain reaction to analyze B and T lymphocyte clonality in pulmonary tissue as a tool for the diagnosis of pulmonary lymphoproliferative disorders.

METHODS

Immunohistochemistry and molecular gene rearrangement analysis were performed in order to assess 8 cases of lymphoid interstitial pneumonia (LIP) and 7 cases of pulmonary lymphoproliferative disorders.

RESULTS

All 8 cases of LIP presented moderate to strong immunostaining for CD3, compared with only 2 cases of lymphoma and 1 case of pseudolymphoma (p = 0.02). Gene rearrangement was detected in 4 of the 8 cases, which changed the diagnosis from LIP to lymphoma, showing the importance of gene rearrangement detection in cases of LIP. In this situation, gene rearrangement using the VH/JH and Vgamma11/Jgamma12 primer pairs was detected in 3 cases and 1 case, respectively, and no gene abnormalities were found using the Dbeta1/Jbeta2 and Vgamma101/Jgamma12 primer pairs in any of the cases. A significant positive association was found between the intensity of CD20 and CD68 expression and gene rearrangement using the VH/JH primer pair. Prior to the gene rearrangement, 4 patients with LIP died quickly, whereas only one patient with LIP died after the gene rearrangement.

CONCLUSIONS

Detection of monoclonal B and T cells by immunophenotyping and polymerase chain reaction had an impact on the diagnosis of pulmonary lymphomas in patients previously diagnosed with LIP. Therefore, immunophenotyping and polymerase chain reaction should be used as 'gold standard' techniques in routine practice.

Cytopathological analysis of vitreous in intraocular lymphoma

OBJECTIVE

To describe the cytopathological method used in the analysis of vitreous samples in the diagnosis of primary intraocular lymphoma (PIOL).

PARTICIPANTS

Seven patients with refractory posterior uveitis referred to a regional ocular inflammatory service were diagnosed as having PIOL between 1999 and 2006.

METHODS

Clinical features of the uveitis and cytopathological preparation of the samples were described. All patients underwent vitrectomy and samples were placed in formal saline or prepared fresh. Following paraffin embedding generating a cell block, immunostaining, and polymerase chain reactions were performed.

RESULTS

Five women (71.4%) and two men (28.6%) (mean age 67.7 years) were included. Five patients had diagnostic vitrectomy performed within 6 months of presentation, but in two patients diagnosis was delayed up to 2 years. Uveitis was bilateral in two patients. Cytologic and immunohistochemical staining prepared from the vitreous specimens showed PIOL in all patients, and PCR displayed single band of immunoglobulin heavy chain rearrangement in five out of six samples tested.

CONCLUSIONS

Diagnosis of PIOL is difficult due to small volume of sample with low number of malignant cells and inadequate preparation of samples. Our method of analysis with fresh samples together with immunohistochemistry and PCR analysis demonstrates a high yield of diagnosis reducing diagnostic delay.