Histopathologic features of retinoblastoma and its relation with in vitro drug resistance measured by means of the MTT assay

Outcomes of pediatric retinoblastoma treated with ICEV regimen: A single-center study

Retinoblastoma is the most common intraocular malignancy in children. The aim of this study was to investigate the efficacy and toxicity of combination ifosfamide, carboplatin, etoposide, and vincristine (ICEV) in advanced-stage pediatric retinoblastoma [International Classification of Retinoblastoma (ICRB) group D or E], and in ICRB group C in the second eye in simultaneously treated bilateral retinoblastoma. The medical records of retinoblastoma patients treated with concurrent ICEV regimen and focal therapy were retrospectively reviewed. The ICEV treatment protocol was, as follows: ifosfamide 1800 mg/m² on Days 1-3; MESNA 600 mg/m² on Days 1-3; carboplatin 560 mg/m² on Day 1; etoposide 150 mg/m² on Days 1-3; and vincristine 1.5 mg/m² on Day 1. Of 16 retinoblastoma patients, 13 had bilateral disease. Seven first eyes in bilateral disease that were enucleated prior to ICEV therapy were excluded. Twenty-two eyes were finally included (six group C, six group D, and ten group E). Median follow-up was 3.4 years, and the median number of ICEV courses was 7. Fifteen globes could be salvaged, 12 responded to ICEV (six group C, five group D, and one group E), and three unresponsive eyes could be salvaged with external beam radiation therapy (EBRT). Enucleation-free and relapse-free survival was 68.2 and 54.5%, respectively. The results of this study suggest ICEV as an alternative therapeutic approach for globe salvage in pediatric retinoblastoma, especially in ICRB groups C and D with manageable acute toxicity. Further study in larger cohort is needed to confirm the effectiveness of treatment.

Loss of photoreceptorness and gain of genomic alterations in retinoblastoma reveal tumor progression

BACKGROUND

Retinoblastoma is a pediatric eye cancer associated with RB1 loss or MYCN amplification (RB1 (+/+) MYCN(A) ). There are controversies concerning the existence of molecular subtypes within RB1(-/-) retinoblastoma. To test whether these molecular subtypes exist, we performed molecular profiling.

METHODS

Genome-wide mRNA expression profiling was performed on 76 primary human retinoblastomas. Expression profiling was complemented by genome-wide DNA profiling and clinical, histopathological, and ex vivo drug sensitivity data.

FINDINGS

RNA and DNA profiling identified major variability between retinoblastomas. While gene expression differences between RB1 (+/+) MYCN(A) and RB1(-/-) tumors seemed more dichotomous, differences within the RB1(-/-) tumors were gradual. Tumors with high expression of a photoreceptor gene signature were highly differentiated, smaller in volume and diagnosed at younger age compared with tumors with low photoreceptor signature expression. Tumors with lower photoreceptor expression showed increased expression of genes involved in M-phase and mRNA and ribosome synthesis and increased frequencies of somatic copy number alterations.

INTERPRETATION

Molecular, clinical and histopathological differences between RB1(-/-) tumors are best explained by tumor progression, reflected by a gradual loss of differentiation and photoreceptor expression signature. Since copy number alterations were more frequent in tumors with less photoreceptorness, genomic alterations might be drivers of tumor progression.

RESEARCH IN CONTEXT

Retinoblastoma is an ocular childhood cancer commonly caused by mutations in the RB1 gene. In order to determine optimal treatment, tumor subtyping is considered critically important. However, except for very rare retinoblastomas without an RB1 mutation, there are controversies as to whether subtypes of retinoblastoma do exist. Our study shows that retinoblastomas are highly diverse but rather than reflecting distinct tumor types with a different etiology, our data suggests that this diversity is a result of tumor progression driven by cumulative genetic alterations. Therefore, retinoblastomas should not be categorized in distinct subtypes, but be described according to their stage of progression.

Local chemotherapeutic agents for the treatment of ocular malignancies

We critically analyze available peer-reviewed literature, including clinical trials and case reports, on local ocular cancer treatments. Recent innovations in many areas of ocular oncology have introduced promising new therapies, but, for the most part, the optimal treatment of ocular malignancies remains elusive.

Differentiation in retinoblastoma and histopathological risk factors in Mexico

PURPOSE

To describe the relationship between retinoblastoma differentiation, histopathological risk factors, age at enucleation, laterality, and genetic type (hereditary or sporadic) in a series of enucleated eyes in a referral hospital. The criteria used in other studies to classify retinoblastoma differentiation are discussed.

METHODS

The authors retrospectively studied histopathological preparations of eyes with retinoblastoma treated with primary enucleation. Tumors were classified as well differentiated, undifferentiated, and moderately differentiated. Patient age at enucleation, laterality of disease, genetic form (hereditary or sporadic), and presence of histopathological risk factors (massive choroidal infiltration, postlaminar optic nerve invasion, tumor in optic nerve cut, scleral invasion, and involvement of orbital soft tissues) were analyzed. The chi-square test was used for categorical variables and analysis of variance for test mean differences.

RESULTS

Histopathological risk factors were present in 23 (36%) of 63 eyes. Moderately differentiated tumors occurred at advanced ages and were more frequently associated with histopathological risk factors.

CONCLUSIONS

A consensus is needed to establish the histopathological criteria of retinoblastoma differentiation. The value of rosettes as a marker of cell differentiation should be reviewed.[J Pediatr Ophthalmol Strabismus 2013;50(3):174-177.].

Clinical pathologic study of a cohort of patients with retinoblastoma from a developing country

PURPOSE

To describe the histopathologic characteristics of all retinoblastoma biopsy specimens received at one institution.

METHODS

All retinoblastoma biopsy specimens received between January 2000 and December 2005 were evaluated and a total of 109 eyes from 101 patients were studied.

RESULTS

There were 9 (8.3%) well differentiated, 25 (23.0%) moderately differentiated, and 66 (60.5%) poorly differentiated retinoblastomas. The most common growth pattern was mixed, comprising 81 (74.4%) cases. Vitreous seeding, invasion of the anterior chamber, and invasion of the optic nerve beyond the lamina cribrosa, was present in 79 (72.5%), 24 (22.0%), and 44 (40.4%) eyes, respectively. The tumor was confined to the retina in only 26 (23.9%) cases, whereas 16 (14.8%) had minimal choroidal invasion, 45 (41.3%) had massive choroidal involvement, 10 (9.2%) had scleral invasion, and 11 (10.1%) had extraocular extension.

CONCLUSION

In this study, the percentage of patients with choroidal and optic nerve invasion, reflecting a poor prognosis, was much higher than in previously reported North American series. However, similar findings have been described in other developing countries, where late diagnosis is common. This study emphasized the need for early diagnosis and treatment.

Sudden dispersion of retinoblastoma shortly after initial chemotherapy treatment

PURPOSE

To present 3 cases of unilateral retinoblastoma that demonstrated unusual tumor dispersion shortly after initial chemotherapy treatment.

DESIGN

Observational case series.

METHODS

Review of medical records of patients in whom intraocular dissemination of retinoblastoma occurred after initial treatment with chemotherapy.

RESULTS

Three patients demonstrated an atypical response with intraocular dissemination of retinoblastoma shortly after 1 cycle of chemotherapy. All cases had unilateral retinoblastoma with no vitreous seeding or subretinal fluid at presentation. In 2 cases (Cases 2 and 3), there were a few distant subretinal seeds. Per the International Classification of Retinoblastoma, 1 tumor was group E (Case 1), and the other 2 tumors were group D1 (Cases 2 and 3). In 2 cases (Cases 1 and 2), chemotherapy included a 2-drug regimen of carboplatin and etoposide; in the third case, a 3-drug regimen of carboplatin, etoposide, and vincristine was used. In each case, the retinoblastoma dispersed with tumor cells in the vitreous shortly after initial chemotherapy treatment, leading to subsequent enucleation of the eye.

CONCLUSIONS

Retinoblastoma can exhibit an unexpected and sudden dispersion of the tumor shortly after chemotherapy is initiated.

The expression of cyclooxygenase 2 in retinoblastoma: primary enucleated eyes and enucleation after conservative treatment

PURPOSE

To provide insight into the relationship between cyclooxygenase-2 (COX-2) expression and histopathologic features of retinoblastoma specimens treated either by primary or secondary enucleation.

DESIGN

Laboratory investigation.

METHODS

Twenty-five retinoblastoma specimens received between 1994 and 2003 were retrieved for this study from the Ocular Pathology Registry, Federal University of São Paulo, Brazil and the Henry C. Witelson Ocular Pathology Laboratory and Registry, McGill University, Montreal, Canada. The specimens retrieved were divided into two groups: Group I, enucleation was performed as a form of primary treatment (n = 15) and Group II, enucleation after failure of conservative treatment (n = 10). Patient information and formalin-fixed, paraffin-embedded specimens were obtained. New sections of these blocks were used for hematoxylin and eosin stain and for immunoassay using a monoclonal mouse anti-COX-2 antibody. Two independent ophthalmic pathologists reviewed all of the microslides.

RESULTS

Twenty-three specimens (92%) presented a high expression of COX-2 (15 in Group I; eight in Group II) and there was no statistical difference in COX-2 expression between the two groups (P = .07). However, all specimens expressed COX-2 to a different degree. The areas of tumor invasion were positive for COX-2 in 87.5% of the two groups.

CONCLUSION

Most retinoblastoma specimens revealed a high COX-2 expression. Future studies will be necessary to correlate the high expression of COX-2 in retinoblastoma and a possible applicability of anti-COX-2 medications in the treatment of these tumors.

Clinical-histopathological correlation in a case of Coats' disease

Background

Coats' disease is a non-hereditary ocular disease, with no systemic manifestation, first described by Coats in 1908. It occurs more commonly in children and has a clear male predominance. Most patients present clinically with unilateral decreased vision, strabismus or leukocoria. The most important differential diagnosis is unilateral retinoblastoma, which occurs in the same age group and has some overlapping clinical manifestations.

Case presentation

A 4 year-old girl presented with a blind and painful right eye. Ocular examination revealed neovascular glaucoma, cataract and posterior synechiae. Although viewing of the fundus was impossible, computed tomography disclosed total exsudative retinal detachment in the affected eye. The eye was enucleated and subsequent histopathological evaluation confirmed the diagnosis of Coats' disease.

Conclusion

General pathologists usually do not have the opportunity to receive and study specimens from patients with Coats' disease. Coats' disease is one of the most important differential diagnoses of retinoblastoma. Therefore, It is crucial for the pathologist to be familiar with the histopathological features of the former, and distinguish it from the latter.

Relationship between histopathological features of chemotherapy treated retinoblastoma and P-glycoprotein expression

BACKGROUND

P-glycoprotein (P-gp) has been identified as a possible mediator of chemoresistance in retinoblastoma. The aim of this study was to determine the expression of P-gp in retinoblastoma treated with chemotherapy prior to enucleation.

METHODS

Seventeen enucleated specimens of retinoblastoma from 16 patients were studied. Nine had been treated with chemotherapy alone, and eight had been treated with chemotherapy and other forms of local treatment. Tumour differentiation as well as choroidal and optic nerve invasion were assessed. P-gp immunohistochemical staining was performed and evaluated as negative, low or high.

RESULTS

Histopathological assessment of the cases showed that 14 of 17 eyes (82.3%) had viable retinoblastoma cells. Nine retinoblastomas were considered regressed with a well-differentiated component, five regressed retinoblastomas had viable cells with poor differentiation and three retinoblastomas had regressed leaving no viable cells. Sixteen of 17 retinoblastomas were P-gp positive. In the one case with optic nerve invasion and the three cases with massive choroidal invasion, P-gp expression was found in invading retinoblastoma cells.

CONCLUSION

Almost all retinoblastomas expressed P-gp. High levels of P-gp expression might play a role in chemotherapy resistance of retinoblastoma or, conversely, chemotherapy might induce P-gp expression. These results might have an impact on management of bilateral retinoblastoma.

Immunocytochemical detection of deoxycytidine kinase in pediatric malignancies in relation to in vitro cytarabine sensitivity

Deoxycytidine kinase (dCK) is essential for the phosphorylation of cytarabine (ara-C), a deoxycytidine analog active against acute leukemias. Resistance to ara-C has been linked to dCK deficiency. In this study we determined the expression of the dCK protein in pediatric malignancies, using immunocytochemistry and related the expression levels to in vitro ara-C sensitivity (measured with the MTT-assay). dCK expression was high in the AML and retinoblastoma samples, in the ALL samples dCK expression ranged from low to very high. The brain tumor samples expressed low levels of dCK. AML was significantly more sensitive in vitro to ara-C compared to ALL (p = 0.03). Retinoblastoma and brain tumor cells were extremely resistant in vitro, we were unable to detect more than 50% ara-C induced cell kill in the majority of samples. Samples were combined in groups according to dCK expression. Samples with low dCK expression were significantly more resistant to ara-C compared to samples with high dCK expression. In conclusion, dCK expression varies between individual samples and between different types of malignancies and may play a role in resistance to ara-C in particular tumor types.