Retinoblastoma: clinical and histopathologic features

Effects and Assessment of the Optic Pathway After Management with Stereotactic Radiosurgery for Intracranial Tumors: A Comprehensive Literature Review

Intracranial tumors are treated through a minimally invasive procedure called stereotactic radiosurgery (SRS), which uses precisely targeted radiation beams. When SRS is used to treat tumors in or near the optic pathway, which is responsible for transmitting visual information from the eyes to the brain, it is essential to assess the effects of treatment on visual function. The optic pathway is considered relatively radiation-sensitive, and high doses of radiation can lead to visual impairment or loss. Various methods can be used to assess the effects of SRS on the optic pathway, including visual acuity testing, visual field testing, and imaging studies. These assessments can be performed before and after treatment to track changes in visual function and detect potential complications or side effects. Assessing the optic pathway after management with SRS for intracranial tumors is essential to the treatment process to ensure that patients receive the best possible outcomes while minimizing the risk of complications. Close collaboration between the multidisciplinary team is often necessary to optimize treatment planning and monitoring of treatment response. In this review, we conducted an extensive analysis of the effects of radiation in patients with intracranial tumors after receiving radiotherapy.

AN IN VIVO STUDY OF INTRAVITREAL RANIBIZUMAB FOLLOWING SUBRETINAL INOCULATION OF RB CELLS IN RABBITS EYES

AIM

This study aimed to determine the effects of a single intravitreal ranibizumab injection in rabbits induced with retinoblastoma (RB).

MATERIAL AND METHODS

RB was induced in six New Zealand white rabbits by subretinal injection of a cultured WERI-RBb-1 cell line into the right eye. After six weeks, Group A (n = 3) was given intravitreal ranibizumab injection (0.3mg in 0.03ml) and Group B (n = 3) was the control. Baseline and serial clinical examinations were performed on days 1, 3, 6, 12, 15, 18 and 21. The right eyes were enucleated for both groups on day 21 for histopathological examination.

RESULTS

The rabbits in both groups developed intraocular lesions which was detectable clinically at one-week post-tumor inoculation. The tumor grew slowly without spontaneous regression. After the animals in Group A were given an intravitreal ranibizumab injection, regression of the tumor was detected clinically, while the tumor in Group B continued to grow slowly. Histopathological findings confirmed the presence of a tumor that closely resembled features of poorly differentiated human RB cells. At the end of 21 days, the size of the tumor was larger in Group B in comparison to Group A. However, the treated group also developed a focal area of retinal hyperplasia. There was no significant side effect of ranibizumab injection except temporary high intraocular pressure immediately post-injection, which was relieved after paracentesis.

CONCLUSIONS

Intravitreal ranibizumab is a potential treatment for RB. It is an effective therapy with a tolerable safety profile in this animal experimental study.

Lurking below: massive choroidal invasion under a calcified tumor after attempted conservative therapy for retinoblastoma

BACKGROUND

In the conservative management of retinoblastoma, detection of tumor activity beneath large, calcified tumors presents a challenging aspect of care as local consolidation is limited in this area. Routine imaging modalities, including magnetic resonance imaging, B-scan ultrasound, and optical coherence tomography, are also limited in providing appropriate surveillance for recurrent disease.

MATERIALS AND METHODS

Medical records were reviewed to evaluate patients' demographic data, ophthalmic exams, imaging studies, and histopathologic reports.

RESULTS

Three patients (two females and one male) were diagnosed with retinoblastoma (two bilateral and one unilateral) and managed with intravenous chemotherapy and local consolidation. In all three cases, the initial tumors regressed to form large, predominantly calcified tumors. However, it was observed that there continued to be nodular recurrences on the surface of the calcium without visible clinical activity at the base of the calcified lesion. All three cases ultimately required enucleation for these active nodular recurrences and massive choroidal invasion was noted under the calcified tumor. Ophthalmic exams and imaging studies did not provide consistent indication of choroidal disease in these cases, and the extensive calcification prevented detection of active disease at the tumor base on fundoscopy.

CONCLUSIONS

Active choroidal disease at the base of large, calcified tumors cannot be ruled out with ophthalmologic examination and noninvasive imaging; suspicion of disease activity at the base should remain high for patients presenting with multiple recurrent nodules over a calcified tumor.

Heterogeneity in retinoblastoma: a tale of molecules and models

Retinoblastoma, an intraocular pediatric cancer, develops in the embryonic retina following biallelic loss of RB1. However, there is a wide range of genetic and epigenetic changes that can affect RB1 resulting in different clinical outcomes. In addition, other transformations, such as MYCN amplification, generate particularly aggressive tumors, which may or may not be RB1 independent. Recognizing the cellular characteristics required for tumor development, by identifying the elusive cell-of-origin for retinoblastoma, would help us understand the development of these tumors. In this review we summarize the heterogeneity reported in retinoblastoma on a molecular, cellular and tissue level. We also discuss the challenging heterogeneity in current retinoblastoma models and suggest future platforms that could contribute to improved understanding of tumor initiation, progression and metastasis in retinoblastoma, which may ultimately lead to more patient-specific treatments.

Atypical intravitreal growth of retinoblastoma with a multi-branching configuration

Purpose

To report the clinical and histopathological findings of atypical intravitreal growth of a retinoblastoma with a multi-branching configuration.

Observations

A 7-month-old boy was referred to our hospital due to leukocoria in the right eye. Ophthalmic examinations identified multi-branching vessels surrounded by diaphanous tissue behind the lens in the right eye. Imaging modalities showed microphthalmos, band-shaped calcification, and cystic lesions in that eye. Because it was difficult to rule out congenital anomalies such as persistent fetal vasculature due to the atypical clinical features of retinoblastoma, we performed a biopsy using a limbal approach. An intraoperative rapid pathological examination led to the definitive diagnosis of retinoblastoma. The right eye was enucleated and postoperative adjuvant chemotherapy was administered. Immunohistochemical staining of the enucleated eyeball showed that the tumoral cells and diaphanous tumoral tissue around the vessels were positive for neuron-specific enolase and Ki-67 and partially positive for glial fibrillary acidic protein (GFAP). The vessels of the diaphanous tissues near the tumoral mass were stained by GFAP and those behind the lens were stained faintly.

Conclusions and importance

We described an atypical retinoblastoma of pseudo-persistent fetal vasculature with a multi-branching configuration, which expanded the clinical spectrum of retinoblastoma. Such a specific growth pattern of the embryonic tumor might occur with a combination of retinal development, retinal vasculature, and hyaloid vascular system.

Presentation of retinoblastoma patients in Malaysia

BACKGROUND

Retinoblastoma is a rare type of cancer that usually develops in early childhood. If left untreated it can cause blindness and even death. The aim of this study is to determine sociodemographic and clinical features of retinoblastoma patients and also to determine the treatment pattern and outcome in Malaysia.

MATERIALS AND METHODS

Data for this study were retrieved from the Retinoblastoma Registry of the National Eye Database (NED) in Malaysia. Hospital Kuala Lumpur, Hospital Umum Kuching, Sarawak and Hospital Queen Elizabeth, Kota Kinabalu were the major source data providers for this study. Data collected in the registry cover demography, clinical presentation, modes of treatment, outcomes and complications.

RESULTS

The study group consisted of 119 patients (162 eyes) diagnosed with retinoblastoma between 2004 and 2012. There were 68 male (57.1%) and 51 (42.9%) female. The median age at presentation was 22 months. A majority of patients were Malays (54.6%), followed by Chinese (18, 5%), Indians (8.4%), and indigenous races (15.9%). Seventy six (63.8%) patients had unilateral involvement whereas 43 patients had bilateral disease (36.1%). It was found that most children presented with leukocoria (110 patients), followed by strabismus (19), and protopsis (12). Among the 76 with unilateral involvement (76 eyes), enucleation was performed for a majority (79%). More than half of these patients had extraocular extension. Of the 40 who received chemotherapy, 95% were given drugs systemically. Furthermore, in 43 patients with bilateral involvement (86 eyes), 35 (41%) eyes were enucleated and 17 (49%) showed extraocular extension. Seventy-two percent of these patients received systemic chemotherapy. The patients were followed up 1 year after diagnosis, whereby 66 were found to be alive and 4 dead. Sixteen patients defaulted treatment and were lost to follow-up, whereas follow-up data were not available in 33 patients.

CONCLUSIONS

Patients with retinoblastoma in this middle-income Asian setting are presenting at late stages. As a result, a high proportion of patients warrant aggressive management such as enucleation. We also showed that a high number of patients default follow-up. Therefore, reduction in refusal or delay to initial treatment, and follow-up should be emphasized in order to improve the survival rates of retinoblastoma in this part of the world.

Metastatic retinoblastoma presenting as a left shoulder soft tissue mass: FNA findings and review of the literature

Retinoblastoma is a relatively rare malignant pediatric tumor accounting for approximately 3% of childhood cancers and 1% of all cancer deaths in children under 15 years of age. During the clinical course of the disease, a metastasis usually occurs within the first year of diagnosis and is seen in 2% of retinoblastoma patients. Metastases to the intracranial region are common and account for approximately 50% of the metastatic cases. Metastasis to the soft tissue is very rare. Herein, we report a case of metastatic retinoblastoma presenting as a left shoulder soft tissue mass in a 14-year-old female with a 14-year history of familial bilateral retinoblastoma status post radiation therapy. In our case, the FNA cytology shows some features of the small round blue cell tumor group with inconspicuous Flexner-Wintersteiner or Homer-Right rosette formation. The unusual clinical presentation and morphology give rise to a diagnostic dilemma, with the differential diagnosis centering on the small round blue cell tumors such as lymphoma, rhabdomyosarcoma, nephroblastoma (Wilms' tumor), Ewing's sarcoma/PNET, and desmoplastic small round cell tumor. It also prompts concern for the development of a second primary tumor. The purpose of our study is to discuss the FNA cytology of metastatic retinoblastoma, its differential diagnoses, and the utility of immunohistochemistry. An accurate diagnosis is imperative due to the differences in prognosis and treatment implications for the various diseases.

The triad of bilateral retinoblastoma, dysplastic naevus syndrome and multiple cutaneous malignant melanomas: a case report and review of the literature

We report a case of a patient with the triad of retinoblastoma, dysplastic naevus syndrome (DNS) and multiple cutaneous melanomas. The combination of retinoblastoma and DNS is a significant risk factor for the development of cutaneous melanoma. This risk extends to family members. We recommend that survivors of (inherited) retinoblastoma and their relatives are closely screened for the presence of dysplastic naevi.

[Morphologic classification of choroidal invasion of retinoblastoma]

In order to inquire into standard for morphologic classification of choroidal invasion of retinoblastoma and to study the tumor clinic--pathologic further under the integrated scale, the changes of retinal pigment epithelium, Bruch's membrane and choroid on the histopathological sectins of 297 cases of primary enucleated eyes of retinoblastoma were retrospectively observed under the light microscopy. The choroidal invasion was morphologically divided into four stages: Stage 1, only retinal pigment epithelium involved, the Bruch's membrane was intact; Stage 2, the Bruch's membrane was destroyed and the choroidal capillaris was not infiltrated; Stage 3, choroial capillary and middle blood vessel layer in small limits were infiltrated; Stage 4, invasion involved in choroid in great limits and involvement of sclera existed simultaneously. This classification (also called pigment epithel--choroid stage, PEC--stage) reflected both infiltrated procedure of tumor cells and preventive mechanism in eye and morphological criterion half--quantitatively. It can be used as a united standard to compare the infiltration degree of retinoblastoma among different individuals and different studies.

Pediatric tumors in north west Pakistan and Afghan refugees

All patients referred to the Institute of Radiotherapy and Nuclear Medicine in Peshawar (IRNUM) during 1990 to 1994 were analyzed. There were 1655 children with biopsy-proven cancers; 1290 were from the North West Frontier Province (NWFP), and the remaining 365 were Afghan refugees. Male children from the NWFP were 67% and females were 33%. Among Afghan children, 69% were males and 31% were females. Patients whose histopathologies were doubtful or not available were excluded from the study. The most common tumors in children in the NWFP were lymphoid leukemia, lymphoma, myeloid leukemia, Wilms tumor, tumors of the central nervous system (CNS), soft tissue sarcoma, bone tumors, retinoblastoma, neuroblastoma, and testicular tumors. Among Afghan children the most common cancers were lymphoma, lymphoid leukemia, myeloid leukemia, Wilms tumor, retinoblastoma, tumors of soft tissue, bone tumors, CNS tumors, testicular tumors, and neuroblastoma.

Recommendations for the use of routine bone marrow aspiration and lumbar punctures in the follow-up of patients with retinoblastoma

PURPOSE

Patients with metastatic retinoblastoma have a poor outcome. Hope that early detection of extraocular spread will improve survival has led to routine monitoring with bone marrow and cerebrospinal fluid (CSF) examinations. In light of cost and patient morbidity, the clinical utility of this practice is questioned.

PATIENTS AND METHODS

We have performed 254 serial bone marrow aspirations and 164 lumbar punctures in 60 children with retinoblastoma.

RESULTS

Two patients with extensive intraocular disease at diagnosis developed positive bone marrow aspirations, although no patient died of distant metastasis. Three patients developed positive CSF examinations. All had neurologic symptoms at the time of CSF positivity.

CONCLUSIONS

We recommend performing staging bone marrow and CSF evaluations only in patients with clinical, histologic, or radiologic evidence of local or systemic extension (Pratt stage III-IV), or in patients presenting with one Reese-Ellsworth group V eye and retrolaminar or extrascleral extension of their tumor. We recommend limiting follow-up bone marrow and CSF evaluations to patients who develop objective signs and symptoms of metastatic or regionally recurrent disease.

Imaging in the trilateral retinoblastoma syndrome

The medical records, CT, and MRI of ten children with trilateral retinoblastoma were reviewed. The intracranial pathology consisted of eight pineal neoplasms and two parasellar lesions, at least seven of the which were calcified. Two lesions demonstrated calcification only (no soft tissue mass) at initial presentation. Hydrocephalus was seen in eight cases, and concurrent or subsequent subarachnoid dissemination was documented in seven. Only one patient is known to be alive at the present time. The imaging features of the midline intracranial tumors mirror those of the ocular neoplasm. As calcification may be the only clue to the presence of the intracranial malignancy, close surveillance of high-risk patients with retinoblastoma with initial CT and follow-up MRI is suggested.

Optic nerve invasion of retinoblastoma. Metastatic potential and clinical risk factors

BACKGROUND

Optic nerve invasion is one of the predictors for retinoblastoma metastases. This study was designed to investigate the risk of optic nerve invasion and clinical features that may identify those children with optic nerve invasion.

METHODS

We reviewed the charts of 289 children with retinoblastoma treated initially with enucleation. Logistic regression analysis was performed to assess the risk for metastases from varying degrees of optic nerve invasion and to assess the clinical and histopathologic predictors of optic nerve invasion.

RESULTS

There were 84 eyes (29%) with optic nerve invasion. The invasion was prelamina cribrosa in 44 cases (15%), up to but not posterior to the lamina cribrosa in 21 cases (7%), posterior to the lamina cribrosa but not to the cut end of the optic nerve in 17 cases (6%), and to the site of optic nerve transection in 2 cases (1%). Patients with optic nerve invasion were more likely to develop metastasis (P = 0.0016), particularly those with invasion to the postlaminar and cut section of the optic nerve (P = 0.0001). Development of metastasis was not statistically associated with laminar or prelaminar involvement. If those patients with choroidal invasion simultaneous with optic nerve invasion were excluded from evaluation, the presence of optic nerve invasion alone was not significant for development of metastasis. The clinical factors found to be predictive for optic nerve invasion from a univariate analysis included exophytic growth pattern (P = 0.011), elevated intraocular pressure (> 22 mm Hg) (P = 0.02), and tumor thickness greater than or equal to 15 mm (P = 0.03). The histopathologic factor significantly associated with optic nerve invasion (univariate analysis) was simultaneous choroidal invasion (P = 0.001). A trend toward an association with optic nerve invasion was found with vitreous hemorrhage (P = 0.06), iris neovascularization (P = 0.10), and poorly differentiated retinoblastoma (P = 0.07). A multivariate analysis showed the most significant clinical factors to be exophytic growth pattern (P = 0.002), tumor thickness greater than or equal to 15 mm (P = 0.01), and vitreous hemorrhage (P = 0.05).

CONCLUSIONS

Optic nerve invasion of retinoblastoma beyond the lamina cribrosa is associated with a greater metastatic risk. Large exophytic retinoblastoma with secondary glaucoma is at highest risk for optic nerve invasion.

Choroidal invasion of retinoblastoma: metastatic potential and clinical risk factors

There is considerable debate about the significance of choroidal invasion of retinoblastoma with regard to metastatic disease. The charts of patients with retinoblastoma were reviewed over a 17 year period to determine the frequency of histopathological choroidal invasion of retinoblastoma and its risk for eventual metastatic disease. Sixty seven of 289 eyes (23%) enucleated for retinoblastoma had histopathological evidence of choroidal invasion. Those patients with choroidal invasion (with or without optic nerve invasion) were more likely to develop metastases than those without choroidal invasion (p = 0.0001). When considering those patients with isolated choroidal invasion of retinoblastoma, excluding those with associated optic nerve invasion, there was no significant risk but there was a trend towards the development of metastases (p = 0.10). The clinical factors found to be predictive for choroidal invasion from retinoblastoma from a univariate analysis included increased intraocular pressure (p = 0.04) and iris neovascularisation (p = 0.007) and, from a multivariate analysis, iris neovascularisation (p = 0.02). The histopathological factors statistically associated with choroidal invasion included the presence of optic nerve invasion (p = 0.002) and poorly differentiated retinoblastoma (p = 0.003). Factors not predictive for choroidal invasion included the age, race, and sex of the patient and the tumour laterality, inheritance, size, and growth pattern. Choroidal invasion of retinoblastoma is a risk for metastases, especially if it is associated with any degree of optic nerve invasion.

A reassessment of histologic classification and an immunohistochemical study of 88 retinoblastomas. A special reference to the advent of bipolar-like cells

BACKGROUND

Despite perpetual efforts of investigators, the histogenesis of retinoblastoma is still in dispute and histologic classification satisfactorily predictive of prognosis does not seem to be in use.

METHODS

The authors studied 88 cases of retinoblastoma clinicopathologically and immunohistochemically, paying special attention to the presence of a "bipolar-like cell" element that would be used as one of the criteria for the diagnosis of differentiated retinoblastoma.

RESULTS

Twelve cases of retinoblastoma with the bipolar-like cell element in the absence of rosettes and 41 cases of the tumor with rosettes were classified as differentiated retinoblastomas. The other 35 cases without rosettes or bipolar-like cells were classified as undifferentiated tumors. Tumor cells forming rosettes usually had positive results for synaptophysin and neuron-specific enolase (NSE) and negative results for glial fibrillary acidic protein (GFAP) and S-100 protein; however, undifferentiated cells had negative results for these four antibodies. The bipolar-like cells had positive results for synaptophysin and NSE but negative results for GFAP and S-100 protein. Twelve tumors with bipolar-like cells that lacked rosettes showed no optic nerve invasion, and the patients had a significantly better prognosis (100% 5-year survival rate) than 35 patients with undifferentiated tumors (71% 5-year survival rate) (P < 0.01).

CONCLUSIONS

The findings support a neuronal origin of the tumor and indicate that, not only the rosettes symbolizing the photoreceptor differentiation, but also other neuronal elements, such as bipolar-like cells, can be used as criteria for histologic classification of retinoblastoma.

A prospective study on the treatment of retinoblastoma in 72 patients

Seventy-two patients with retinoblastoma (RTB) (unilateral [47 patients] and bilateral [25 patients]) were studied for a period of 6 years. Treatment consisted of enucleation of those eyes that had severe involvement and was followed by radiation therapy and/or chemotherapy (systemic or intrathecal) according to clinical pathologic staging. All patients who underwent nonsurgical treatment received systemic chemotherapy. Intrathecal chemotherapy was administered when there was involvement of the central nervous system. Nonsurgical treatment consisted of radiation therapy and/or light coagulation, followed by enucleation if there was no response. The overall survival rates were 79% for unilateral disease (median follow-up time, 63 months) and 72% for bilateral disease (median follow-up time, 81 months). Vision was regained in 14 of 21 conserved eyes.

Histopathologic verification of Verhoeff's 1918 irradiation cure of retinoblastoma

The authors studied an eye obtained postmortem from the first patient with a successfully irradiated retinoblastoma. This patient, first treated by Verhoeff in 1917, had been followed for 71 years. Ophthalmoscopy disclosed a depressed chorioretinal scar, approximately 3 disc diameters (DD) in size, with baring of the sclera temporal to the macula. This case is historically significant, in that Verhoeff and Reese debated as to whether this tumor regressed spontaneously or secondary to irradiation. Results of histopathologic, immunohistochemical, and ultrastructural examination showed a chorioretinal, neuroglial scar without evidence of calcification, necrotic tumor cells, or residual retinoblastoma. The authors discuss the clinical and histopathologic findings in spontaneously regressed retinoblastoma, retinoma/retinocytoma, and irradiated retinoblastoma. They believe that Verhoeff was correct in his belief that x-ray therapy had cured this patient.

Histopathological evaluation for the prognosis of retinoblastoma

In the present study histologic, clinical and follow-up data of 37 cases of retinoblastoma were statistically analyzed by means of a multivariate method. The evaluated histological parameters were: growth pattern, degree of differentiation, number of mitoses, presence of necrosis, pseudorosettes, blood vessel basophilia, calcification, extension to anterior chamber, invasion of optic nerve and ocular coats (choroid and sclera). The analysis was based upon the Cox proportional hazards regression model. Invasion of ocular coats proved to be highly correlated to the prognosis (p less than 0.0002). None of the other parameters showed a significant relation to survival.

A study of 39 retinoblastomas with particular reference to morphology, cellular differentiation and tumour origin

A series of 39 retinoblastomas was studied using light microscopy and immunohistochemistry for localization of neurone-specific enolase and glial fibrillary acidic protein. Thirty-eight retinoblastomas (97.4%) occurred in children less than 6 years of age: one was in a 61-year-old man (2.6%); the mean age, excluding the 61-year-old, was 32.1 months. Unilateral tumours were found in 74.4% of patients and bilateral tumours in 25.6%; bilateral lesions occurred in a younger age group, mean age of 21.7 vs 35.9 months. The male to female ratio was 1.4:1. Morphologically, arrangement of tumour cells into trabeculae was noted in 69.2% of retinoblastomas and glomerulus-like structures in 43.6%. These two patterns of cellular arrangement were encountered where the choroid and sclera were invaded by neoplastic cells. Homer Wright rosettes were observed in all tumours. Flexner-Winstersteiner rosettes in 33.3% and fleurettes in 2.6%. Differentiation into neoplastic neurones as well as in the form of Flexner-Winstersteiner rosettes and fleurettes was noted in 46.1%, neoplastic ependymal cells in 100.0%, astrocytes in 58.9%, oligodendrocytes in 23.1%, and glioblastomas in 2.6%. These data suggest that retinoblastoma is a primitive stem cell neuroectodermal tumour with the capacity for differentiation in both neuronal and neuroglial directions.

Aspiration cytology of retinoblastoma: light and electron microscopic correlations

A series of 16 cases of retinoblastoma diagnosed by fine-needle aspiration biopsy (FNAB) and confirmed by histologic examination is reviewed, and the salient cytomorphologic features are described. Two types of cells were encountered in the aspiration smears; type I cells were undifferentiated while type II cells showed more differentiation and frequently revealed cytoplasmic processes that are probably indicative of early photoreceptor differentiation. Flexner-Wintersteiner rosettes characteristic of retinoblastoma were found in 10 of 16 cases. These findings were further correlated with ultrastructural examination of the tumors in nine cases. It is concluded that the presence of rosettes and type II cells with cytoplasmic processes are the two features that are most helpful in the FNAB diagnosis of retinoblastoma.

Treatment of retinoblastoma. Results obtained from a prospective study of 51 patients

During 4 years, 51 patients with retinoblastoma were studied (unilateral 32, and bilateral 19). Treatment consisted of enucleation of those eyes which showed massive involvement followed by radiotherapy when there was optic nerve and/or orbit involvement. Systemic chemotherapy was administered to all patients who underwent nonsurgical treatment and when the histologic examination showed choroidal optic nerve head and/or optic nerve involvement or residual tumor after enucleation. When there was compromise of the central nervous system intrathecal chemotherapy was administered. Nonsurgical treatment consisted of radiotherapy and/or light coagulation. Survival was 90.6% for unilateral cases and 84.2% for the bilateral. The median follow-up was 31 months and 29 months, respectively. Of 19 conservated eyeballs, 16 preserve useful vision (63%).

Structural characterization of neovascularization in adenovirus-12-induced retinal tumor

In order to elucidate a relationship between newly formed micro-blood vessels in retinal tumor and blood-retina barrier, we studied light and electron microscopic and immunohistochemical findings of newly-formed micro-blood vessels in human adenovirus 12-induced retinoblastoma-like tumors in rats. In contrast to other experimentally induced tumors of the central nervous system, there was no evidence of formation of Weibel-Palade bodies and endothelial gaps in this experimental model of retinoblastoma, but factor VIII related antigen was evidently demonstrated. Increased pinocytotic vesicles suggested that the vast majority of these blood vessels did not retain the normal physiological barrier functions. The basement membrane of the micro-blood vessels was poorly developed. The morphological characteristics of the micro-blood vessels of this retinoblastoma-like tumor were compared with those of human retinoblastoma and other experimentally induced tumors of the central nervous system.

Retinoblastoma cell differentiation in culture

Human retinoblastoma cells were grown in tissue culture and their differentiation into Flexner-Wintersteiner rosettes was investigated. This process of photoreceptor cell differentiation was only observed in primary cultures and subsequent cell passages of tumors which showed these structures in vivo. Rosettes formed spontaneously within 5-9 d after plating of the tumor cells. Under optimal conditions in certain tumor cell strains, up to 80% of the cultured cell aggregates contained one or more differentiated Flexner-Wintersteiner rosettes. Exposure of retinoblastoma cells to RA or dcAMP did not alter the number of rosettes in culture. Retinoblastoma cells within rosettes continued to synthesize DNA, and mitotic figures were frequently observed in histological sections. Ultrastructural analysis of rosettes formed in vitro showed many of the characteristics described in those found in vivo including a polarized shape, established cell junctions (Zonula adherens), extensive accumulation of mitochondria and microtubules in the apical part of the cells, numerous basal bodies and centrioles as well as cilia typical of the mature photoreceptor cell. Lamellated stacks of membranes were also found and their nature is discussed.

Ultrastructural correlation of specular microscopy in retinoblastoma

A patient with monocular retinoblastoma was examined with the wide-field specular microscope before undergoing enucleation. An unusual image on the corneal endothelium consisted of irregular oval dark structures within which bright reflections formed a lacy network. Light and electron microscopy confirmed these structures to be clusters of retinoblastoma cells adherent to the endothelium. These findings suggest that the specular microscope may aid in the diagnosis of intraocular tumors.

The use of magnetic resonance imaging in the evaluation of retinoblastoma

We examined a 4-year-old boy who had a painful blind eye, rubeosis iridis, and leukokoria. Ultrasonography and computed tomography (CT) detected intraocular calcification and other features suggestive of retinoblastoma. The CT scan showed extraocular extension along the optic nerve. Intracranial extension of the tumor could not be definitely excluded by CT scan with intrathecal metrizamide infusion. Magnetic resonance imaging (MRI) and CT performed after radiation and chemotherapy were useful in excluding intracranial spread of malignant cells, thereby aiding the selection of a surgical approach to ensure complete removal of the involved portion of the optic nerve.

Retinoblastoma in Lebanon

The data on 58 patients with retinoblastoma managed at the American University of Beirut, Medical Center over the last 35 years is reviewed. The epidemiology, genetics and clinical features of this tumor appear to be the same in the Middle-East as well as the rest of the world. The notable difference between the data in this study and that from other studies is the marked delay in diagnosis of the tumor in this part of the world leading to a higher incidence of extraocular extension, a more advanced stage of the disease and poorer survival rates. This seems to be a feature of medically underdeveloped societies. Increased public awareness of the early signs and symptoms of the disease, as well as routine fundoscopy on all infants are advocated to improve early detection, leading to improved survival rates and prevention of unnecessary enucleations.

Cutaneous malignant melanoma and bilateral retinoblastomas: a case report and review of the literature

Retinoblastoma survivors following successful treatment have a predilection to develop other malignant neoplasms. This report describes a patient with bilateral retinoblastomas diagnosed and treated early in life, who developed cutaneous malignant melanoma 20 years later. In our review of the literature only 5 cases with this association have been reported. We would like to report the sixth case.

Trilateral retinoblastoma: ocular and pineal retinoblastomas

Trilateral retinoblastomas, the syndrome of bilateral retinoblastoma associated with ectopic retinoblastoma in the pineal gland, is rare but well recognized. In contrast to bilateral retinoblastomas alone, the ocular retinoblastomas in trilateral retinoblastoma develop before the age of 6 months, and a family history positive for retinoblastoma is usually obtained. The retinal tumors are often quiescent at the time that the pineal tumor is discovered, and show no evidence of metastatic spread after enucleation of the globes. Pathologically, the pineal tumor is indistinguishable from the ocular retinoblastoma. The pathophysiology of this syndrome is not well understood, but a germinal mutation is thought to target photoreceptor tissue for further postzygotic mutation. Eventual expression depends on the inherited host resistance to the carcinogenic manifestation of these genes. The low host resistance of trilateral retinoblastoma is evident by the early age of presentation, the multicentric occurrence of the tumor, and the high early mortality rate despite aggressive management.

Fine-needle aspiration biopsy diagnosis of round cell malignant tumors of childhood. A combined light and electron microscopic approach

A series of fine-needle aspiration biopsies (FNAB) from 76 children with round cell malignant tumors was studied by both light and electron microscopy. In 14 cases the material submitted for electron microscopy was inadequate, whereas in the remaining 62 biopsies a definitive diagnosis could be made. These included 29 malignant lymphomas, 8 neuroblastomas, 12 Ewing's sarcomas, 3 metastatic retinoblastomas, 3 Wilms' tumors, 3 rhabdomyosarcomas, and 4 unclassified tumors. The results from this study indicate that FNAB studied by light and electron microscopy can be effective in diagnosing small cell tumors in children.

Perinatal (congenital and neonatal) neoplasms: a report of 110 cases

One hundred ten congenital and neonatal tumors encompassing a 25-year period are described and compared with similar published cases. Forty percent are classified as histologically malignant, and 65% of neonates with malignancies died. The types, frequency, and clinical features of neoplasms encountered in the perinatal period are markedly different from those observed in older children and adolescents. Their biological behavior and response to therapy are also dissimilar. Leukemia was responsible for the largest number of deaths followed by neuroblastoma and brain tumors.

Incidence and significance of a deletion of chromosome band 13q14 in patients with retinoblastoma and in their families

Ten unrelated retinoblastoma patients were studied cytogenetically with high-resolution prophase banding; two had a deletion of chromosome 13, band q14. Neither of the two patients had any of the congenital defects usually associated with 13q14 deletions. In patient A, the deletion was found to be de novo. Patient B was found to be mosaic for the 13q14 deletion with 54% of the lymphocytes examined having the deletion. This study indicates that the 13q14 deletion may occur in a significant portion of all retinoblastoma cases. Esterase D activity and isozymes were studied also. The significance of findings will be discussed.

Retinoblastoma, eosinophilic granuloma, and malignant melanoma: a case report

The case history of a patient treated for unilateral hereditary retinoblastoma who subsequently developed malignant melanoma and eosinophilic granuloma is presented. Although the association between retinoblastoma and second malignancies including malignant melanoma is established, we have found no reports of third malignancies occurring in such individuals.

Immunocytochemistry of neuronal and glial markers in retinoblastoma

An immunocytochemical study of 30 retinoblastomas was carried out using antibodies to neuronal and glial markers. The tumours were found to react with antibodies to neuron-specific enolase (NSE), a marker for neuronal elements, and S-100 and glial fibrillary acidic protein (GFAP), both of which are proteins present in glia. Two distinct cell populations were found within the tumour: the first, composed of anaplastic tumour cells at various stages of differentiation, showed both NSE and S-100 immunoreactivity; the second cell type, which immuno-stained for S-100 and GFAP, resembled mature glial cells. The results of this study indicate that the retinoblastoma may arise from a pluripotential primitive cell partially retaining neuronal and glial characteristics.

Genetic models of carcinogenesis

The major genetic models of carcinogenesis are critically reviewed to determine their validity and relevance for clinical and experimental oncologists. Of major concern are the "two-hit" theory of Knudson and the host resistance system of Matsunaga. These models may be used to explain the pathobiologic peculiarities of human neoplasms, particularly those occurring in early life. It is proposed that certain benign and regressive tumors encountered in early life are expressions of the activity of the host resistance system.