Retinal thickness is related to refractive error/axial length in normal subjects with regional variations in correlation within the 6-mm macular region. Analysis of macular thickness in the evaluation of macular diseases and glaucoma should be interpreted only in the context of refractive errors and the location of measurement.

The results confirm that EpCAM is vastly expressed in retinoblastoma and point to its use as a target for therapy in the future.

BACKGROUNDMalignant transformation of cells is frequently associated with abnormalities in human leukocyte antigen (HLA) expression. These abnormalities may play a role in the clinical course of the disease, because HLAs mediate interactions of tumor cells with cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Retinoblastoma is the most common intraocular malignant tumor in childhood and is characterized by direct spread to the optic nerve and orbit as well as hematogeneous and lymphatic spread. Little is known about the role of HLA expression in the progression of this malignant disease.METHODSHLA Class I antigen, β2‐microglobulin (β2‐m), HLA Class II antigens, and the antigen‐processing molecules (APMs) of the HLA Class I pathway, including proteasomal subunits (low–molecular mass polypeptide 2 [LMP‐2] and LMP‐10), the transporter‐associated protein (TAP‐1) subunit, the binding protein tapasin, and the chaperone molecule calnexin, were studied in 30 archival retinoblastoma specimens by immunohistochemistry. Immunoanalysis was performed based on the International Histocompatibility Working Group Project Description.RESULTSHLA Class I antigen, β2‐m, HLA Class II antigen, and APMs were positive in 12 tumors with no invasion and were decreased in 13 tumors with choroidal and optic nerve invasion. The difference in HLA and APM expression between the 2 groups was statistically significant (P < 0.001).CONCLUSIONSDecreased expression of HLA was observed in aggressive tumors and in poorly differentiated tumors. The current findings support a role for both CTLs and NK cell‐mediated control of tumor growth in the clinical course of retinoblastoma. Cancer 2004;100:1059–69. © 2004 American Cancer Society.

BACKGROUND The importance of the Fas‐Fas ligand (FasL) mechanism for the immune evasion by tumors provided a strong rationale for the examination of FasL expression in retinoblastoma. In an earlier publication, the authors reported that invasive retinoblastomas decreased Fas expression. Because to the authors' knowledge there is not much information regarding the effect of FasL expression on retinoblastoma, the authors studied the expression of FasL in retinoblastoma and correlated it with invasiveness. METHODS Thirty‐six archival retinoblastoma specimens were divided into 2 groups. Group A (n = 17) was comprised of specimens from tumors with no invasion and Group B (n = 19) was comprised of specimens from tumors with invasion of the choroid (focal, diffuse), optic nerve (laminar, postlaminar, surgical end), and orbit. Sections were immunostained with a monoclonal antibody to FasL and the immunoreactivity was assessed. RESULTS In Group A, FasL was negative in 100% (17 of 17) of the tumor specimens. In Group B, FasL was expressed in 79% (15 of 19) of the tumor specimens (positive in 9 tumors and heterogeneous in 6 tumors). The difference in FasL expression between the two groups was significant (P < 0.001) CONCLUSIONS Increased expression of FasL was observed in specimens taken from patients with aggressive tumors. Thus, Loss of Fas and gain of aberrant FasL expression were common features of malignant transformation. The data suggested that the Fas/FasL pathway is potentially immunosuppressive and may be involved in the escape of retinoblastoma cells from immune destruction. Cancer 2004. © 2004 American Cancer Society.

HLA class I antigen and beta 2 microglobulin are negative in melanomas with no extrascleral extension and liver metastases and weak in melanomas with extrascleral extension and are positive in melanomas with liver metastases. HLA expression is independent of the conventional markers in uveal melanoma.

Retinoblastoma can arise due to mutational inactivation or methylation of RB1 gene promoter. A 600-bp CpG island consisting of the essential promoter is present at the 5' end of RB1 gene. Hypermethylation of the CpG island within the RB1 promoter region has been described in unilateral retinoblastoma. In vitro and in vivo studies have suggested that methylation of the RB1 promoter dramatically reduces gene activity. In the present study methylation status of the CpG island within the promoter region of RB1 gene has been evaluated by methylation specific polymerase chain reaction to define the molecular mechanism responsible for retinoblastoma in Indian patients. One unilateral and two bilateral nonhereditary patients had methylation of the RB1 promoter region in which 6.6% of our patients had complete methylation of the RB1 promoter region. This study shows methylation of RB1 promoter is not a major mechanism for retinoblastoma patients in India. Methylation analysis is used in genetic counseling of the family.

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