Ultrastructural changes of mitochondria in human retinoblastoma: correlation with tumor differentiation and invasiveness.

Retinoblastoma still represents a challenge for pediatric tumors. Mitochondria have been implicated in tumor progression, cell differentiation, and apoptotic pathways. Electron microscopy allows the study of mitochondrial morphology and it is still debated in human retinoblastoma. Demographic, clinical, and histopathological parameters were recorded in 17 enucleated retinoblastoma specimens. Hematoxylin and eosin staining was performed to study tumor characteristics and the extent of invasion in ocular structures. The aim of this study was to describe and analyze the mitochondrial morphology in human retinoblastoma by transmission electron microscopy (TEM). There was a male preponderance in our study. Ages ranged from 2 to 78 months. Histopathological analysis revealed that 15 (88.2 %) tumors were poorly differentiated retinoblastomas. Massive choroidal invasion was the most frequent histopathological high-risk factor among the others. Histopathological high-risk factors were found in 7/17 (41.1 %) cases. Tumor samples of all patients were examined by means of TEM. All cases showed tumor cells with high nucleocytoplasmic ratio. Poorly differentiated retinoblastoma cases showed fewer mitochondria, scant cytoplasm, disorganized organelles (mitochondria), and necrosis, whereas well-differentiated retinoblastomas had larger number of mitochondria and more organized organelles. However, there was no significant difference in mitochondrial changes between invasive and noninvasive tumors. Our study observed that cristolysis and swollen mitochondria were more frequent in retinoblastoma tumors. Understanding the structural and functional characteristics of mitochondria in retinoblastoma might be essential for the design of future therapeutic strategies. The authors have no proprietary or commercial interest in any materials discussed in this article.

A pilot study of vasculogenic mimicry immunohistochemical expression in intraocular melanoma model.

Vasculogenic mimicry (VM) has been recognized as a new form of angiogenesis. However, some previous studies have demonstrated the absence of VM channel in a uveal melanoma xenograft mice model. This study investigated the pattern and distribution of microcirculation in an intraocular animal model. C57Bl/6 mice were randomly divided into 3 groups used for the blood supply models of malignant melanoma. The right eyes of the mice received subretinal injections with B16 melanoma cells and the left eyes were the control. One experimental group mice was randomly sacrificed at days 3, 7 and 14 to evaluate the tumor size and microcirculation by immunostaining with anti-CD34 antibodies, PAS staining and electronic microscopy (EM). Activated-carbon tracing was used to confirm whether the VM structure connected to the host blood circulation at day 14. We observed 3 types of microcirculation patterns in this model. The tracer was used to confirm whether VM structure connected to the host blood circulation. The distribution of VM and MV was not uniform and appeared in patches. As the area of tumor tissue expands, the number of endothelium increases and that of VM decreases. The number of endothelium-dependent vessels correlated with the tumor size (r=0.805, P=0.000), while the number of VM was inversely correlated (r=0.47, P=0.03). The EM results validated the presence of 3 patterns. In conclusion, VM along with endothelium-dependent vessels and MV sustained the blood supply. Tumor cells can obtain oxygen and nutriment through VM and MV besides endothelium-dependent vessels. VM may be a way to adapt to rapid tumor growth and invasiveness.

Malignant amelanotic melanoma behind the left eye in a female Crj:CD(SD)IGS rat: a case report.

A tumor behind the left eye in a female Crj:CD(SD)IGS rat was investigated histopathologically, immunohistopathologically, and electron microscopically. The tumor invaded and destroyed orbital tissues and bones. It consisted of various tumor cells; namely, spindle-shaped, epithelioid, anaplastic melanoma cells, and had prominent eosinophilic cytoplasm and nuclei with a greater variation in size. Immunohistochemically, almost all of the tumor cells were positive for antimelanoma, PNL2 antibody. Ultrastructurally, the tumor cells were rich in small vesicles containing fine granules and filamentous structures. This is the first report describing an amelanotic melanoma in the head of an albino rat.

[Case of corneally displaced malignant conjunctival melanoma].

BACKGROUND: We studied the clinicopathologic characteristics in a patient with malignant conjunctival melanoma associated with corneal invasion. CASE: A 62-year-old man had a small melanocytic lesion of the inferior palpebral conjunctiva. Previously he had undergone excisional biopsy and was diagnosed as having melanocytic hyperplasia without cytological atypia at an other hospital. He developed recurrence and was referred to us. The pigmentary lesion was observed in the entire inferior palpebral conjunctiva. Biomicroscopic examination revealed that there was a granular pigment lesion in the cornea. The patient was diagnosed as having conjunctival melanoma with corneal invasion and treated with orbital exenteration and chemotherapy in our hospital. Clinicopathologic tests revealed malignant melanoma cells invading through the bulbar conjunctiva and into the cornea. Ultrastructural study by electron microscopy of the pigmented tumor cells in the cornea showed several lobations of the nuclei, a large active-appearing nucleolus, and an aberrant granular melanosomal morphology. CONCLUSIONS: The infiltration of palpebral malignant conjunctival melanoma was limited to the epidermis of the cornea.

[Trichromatic method Gomori in anatomopathologic study of ocular structure]. / Metoda tricroma Gömöri aplicata pe structurile globului ocular, sectiuni la parafina.

Histologic sections performed from the anterior and posterior pole of the eye were stained by the trichrome method described by Gomori. There are described details of the cornea and ciliary body in normal and pathologic conditions. There are discussed advantages of this method over routine stained slider, especially in the case of achromic melanoma.

Ultrastructural study of primary lacrimal adenocarcinoma.

PURPOSE: Primary adenocarcinoma of the lacrimal gland is a rare malignant tumor of the orbit. Up to now, there has been no presentation of its ultrastructural features. The histopathological findings and fine structures of one case of adenocarcinoma of the lacrimal gland are described in the present work. METHODS: The patient was a 59-year-old Japanese man with proptosis that had persisted for one month. A tumor was extirpated, and the tissues were prepared for light and electron microscopic examination. RESULTS: Electron microscopic examination demonstrated that the tumor cells had well-developed microvilli and lumens. These ultrastructure features are similar to those seen in adenocarcinomas at other sites. CONCLUSIONS: These observations suggest that the accurate diagnosis of rare malignant adenocarcinoma depends not only on routine techniques such as light microscopy of hematoxylin-eosin and PAS-diastase stained slides, but also on electron microscopic findings.

Angiomorphology of the pigmented Bomirski melanoma growing in hamster eye.

An melanotic line of Bomirski Hamster Melanoma (BHM Ma) was implanted into the anterior chamber of the hamster eye and the ensuring vascular system was studied using scanning electron microscopy (SEM) of vascular corrosion casts. The tumor vasculature, induced mainly from the host iris vessels, showed generally disorganized and irregular patterns. Tortuous tumor capillaries of uneven contour with local dilatations and constrictions were drained by markedly dilated, thin-walled, venous vessels connected with the eye veins. Vascular sprouting and, less frequently, intussusceptive formation of new vessels were observed at the periphery and also within the tumor mass. The presence of numerous nodular outgrowths, varying in size, on the surface of dilated venules and venous vessels represent morphological evidence for continuous remodeling of the tumor vasculature. The observed features of the vascular system seem to provide a pathway for further tumor expansion. Our study showed that BHM Ma line, originating from an aggressive skin melanotic melanoma, implanted to the eye anterior chamber gave rise to rapidly growing tumors with the capability of inducing abundant vasculature which allows metastasis to the lungs, kidneys and regional lymph-nodes.

Alterations in ultrastructure and c-met expression in a case of ocular epithelial dysplasia following topical mitomycin C treatment.

PURPOSE: Topical mitomycin C (MMC) administration is reportedly effective in treating ocular surface neoplasms such as squamous cell carcinoma. We treated a case of ocular epithelial dysplasia that had spread too diffusely to be completely removed. We examined the ultrastructure of and c-met (hepatocyte growth factor receptor) expression in dysplastic epithelial cells from this case to evaluate the efficacy of MMC treatment. METHODS: Specimens of dysplastic epithelial tissue from the corneo-limbal region of a 62-year-old man were obtained before and after topical application of MMC. Specimens were examined ultrastructurally and immunohistochemically with an antibody against human c-met. RESULTS: Following topical application of MMC, the dysplastic epithelium exhibited multilayered epithelial cells similar to those seen before treatment. However, ultrastructural examination showed tight interdigitation between neighboring cells, with no intercellular spaces. Also, the marked immunoreactivity to c-met in the dysplastic epithelial cells before MMC treatment was decreased after treatment. CONCLUSIONS: Ultrastructural observations indicated a restoration of epithelial cellular differentiation following MMC application. The expression of c-met protein was also reduced. Thus, topical MMC was effective in treating epithelial dysplasia of the ocular surface, with no recurrence 15 months post-therapy.

Adenoma of the pigmented ciliary epithelium: ultrastructural and immunohistochemical findings.

We report the clinical and histological findings in a tumor of the pigmented ciliary epithelium. The tumor was detected because it had caused a unilateral cataract, and it was removed by local resection because a malignant melanoma could not be excluded. The diagnosis was established by light microscopy, and additional immunohistochemical and detailed ultrastructural studies were performed. The so-called foam cells which are considered typical of these adenomas appear to be mostly light microscopic artifacts and had no ultrastructural equivalent in the sections examined from our tumor. Our results also strongly support the hypothesis that no true glandular elements are formed and that, apart from the neoplastic tissue architecture, most of the pathological findings are related to melanosomes.

Immunohistochemical and ultrastructural analysis of dysplastic epithelium of human ocular surface: basement membrane and intermediate filament.

PURPOSE: The dysplastic corneal epithelium is characterized by the abnormal proliferation of epithelial cells. The phenotypes of these cells have not been elucidated. We investigated whether such epithelium expresses the phenotypes of corneal or conjunctival epithelial cells. METHODS: The corneas and conjunctivae from four normal subjects and from one patient with epithelial dysplasia of the central cornea were immunostained for IV and VII collagens and for cytokeratins. Monoclonal antibodies against collagen IV reacted to the [alpha1(IV)]2alpha2(IV) or alpha5(IV) molecule. Anti-cytokeratin antibodies were used to define epithelial cell types. The ultrastructure of the basement membrane (BM) of each specimen also was examined. RESULTS: Type VII collagen immunoreactivity was detected in all the specimens of epithelial BM. The anti-collagen IV [alpha1(IV)]2alpha2(IV) antibody labeled the conjunctival BMs, not the BMs of the corneal epithelia, of each subject. The normal corneal epithelial BM, not the BM of the conjunctival or dysplastic corneal epithelium, was immunolabeled with anti-alpha5(IV) antibody. The pattern of cytokeratin expression in the corneal epithelial dysplasia resembled that seen in the normal conjunctivae. Small breaks in the BM of dysplastic corneal epithelium were ultrastructurally revealed. The number of hemidesmosomes in the dysplastic corneal epithelium was decreased as compared with that in the normal BM. CONCLUSION: The composition of collagen types within the BM and the cellular phenotype of the dysplastic epithelium in the cornea resembled those of conjunctival epithelium, not of the cornea.

Ocular adnexal oncocytoma: a case series and clinicopathologic review of the literature.

The authors report the clinical, microscopic, and ultrastructural features of four oncocytic lesions involving the ocular adnexa. Three of the lesions originated in the ocular caruncle of elderly women, and a single case was encountered from the medial eyelid of an elderly man. Each lesion clinically presented as a slow-growing, painless, red mass. The histopathologic features were distinctive, with polyhedral cells containing granular eosinophilic cytoplasm found to consist of large numbers of mitochondria on ultrastructural examination. Of the 40 cases previously reported primarily in the ophthalmologic literature, the cases reported here similarly involved the eyelid and associated ocular adnexa with a predilection for elderly women. Oncocytomas probably represent an age-associated metaplastic and neoplastic transformation of the glandular epithelium comprising the ducts of salivary glands.

Microscopic and ultrastructural aspects in retinoblastoma.

A number of 12 retinoblastoma cases were studied. We had in view a number of histopathological aspects (tumor type, neighbouring structures invasion) which are considered to be decisive in appreciating the vital prognosis. We mention that undifferential retinoblastoma of histopathological type was met in 8 cases and the neighbouring structures invasion was present in 7 of them. We also studied the ultrastructura of the tumor cells belonging to the malignant tumor.

Human retinoblastoma: a morphological study of apoptotic, leukocytic, and vascular elements.

Retinoblastoma (Rb), derived from retinal neuroepithelial progenitor cells, is the most common intraocular malignancy of childhood. This study examined 10 human Rb biopsy specimens with light and electron microscopy for histopathological features not previously described in detail, including cell death, leukocytic infiltration, and the tumor vasculature. Rb is a solid well-vascularized tumor with regions of viable tumor cells surrounding vessels, interspersed with zones of necrosis; apoptotic cells were seen in all specimens. Mononuclear phagocyte series (MPS) cells and lymphocytes often colocalized, adjacent to tumor vessels, and MPS cells frequently invested the perivascular space. Lymphocytes were rarely seen within areas of viable tumor. Tumor vessels at early stages of formation resembled normal developing retinal vessels. While junctions were often seen between endothelial calls, disruption of these junctions and endothelial fenestrae was sometimes evident. Müller cells and astrocytes extended processes around tumor cells and blood vessels, and contributed to the formation of the vascular glia limitans, which in some mature vessels was disrupted and discontinuous. Overall, this study provides further morphological details of cell death within Rb, particularly apoptotic involution, and describes the presence of a vascular-associated leukocytic infiltration in Rb. Evidence of compromise of the normal blood-retinal barrier (BRB) within the Rb tumor vessels is presented.

Nonteratoid medulloepithelioma of the retina with electron microscopic and immunohistochemical characterization.

Medulloepitheliomas are rare intraocular tumors, predominant in children, and originate mainly from undifferentiated nonpigmented epithelium of the ciliary body. These tumors rarely involve the optic nerve or the retina. They are classified as nonteratoid and teratoid types; the latter contains heterologous tissues. The teratoid variant of medulloepitheliomas involving the optic nerve or the retina is reported in four patients only. We describe the first case of a benign nonteratoid medulloepithelioma of the retina in a 3 1/2-year-old girl with immunohistochemical and electron microscopic characterization.

Clinical and electron microscopic features of retinoblastoma.

A male child of 1-year, 6-month-old had a history of leukocoria of the left eye for approximately three months prior to admission into our facility. No abnormality was found in the right eye. There was negative family history of retinoblastoma. Ophthalmoscopy revealed a white mass extending from the supero-posterior part of the left globe to the posterior surface of the lens. Orbital tomograms showed no intraocular tissue densities in the mass but a B-scan ultrasound showed an echo dense area of the mass. Histopathologically areas of photoreceptor differentiation and Flexner-Wintersteiner rosettes were observed in the tumor mass by light microscope. Transmission electron microscopy disclosed the presence of prominent mitochondria on the luminal side of the cells forming rosettes and these were believed to be the component parts of the inner-segments of the photoreceptor cells. The results of this study indicate a predominant neuronal nature of the neoplastic cells with photoreceptor-like differentiation.

Oxyphil cell adenoma (oncocytoma) of the lacrimal caruncle: a case report.

The onset of oncocytic neoplasms in the ocular area is exceptional. A rare case of oxyphil cell adenoma of the lacrimal caruncle in an 81-year-old woman is presented. The anatomo-clinical profile of this benign small tumor is drawn up: a slowly growing tumor, generally occurring in the caruncle of elderly women, which is characterized by a uniform population of epithelial cells with eosinophilic finely-granular cytoplasm containing large numbers of mitochondria. The histogenetic problem of this tumor is briefly discussed.

Multiple endocrine neoplasia type two B. A case report with light and electron microscopic and immunohistochemical correlation.

PURPOSE: To describe a case of multiple endocrine neoplasia type two B (MEN IIB) where ocular and systemic clinicopathological findings are correlated, in association with light and electron microscopic and immunohistochemical findings. METHODS: A 23-year-old man presented with mucosal neuromas of the lips, tongue and eyelids, a Marfanoid habitus and prominent corneal nerves. These findings led to the diagnosis of multiple endocrine neoplasia type two B. The patient subsequently developed phaeochromocytoma and metastatic medullary thyroid carcinoma (MTC) which led to his demise. Correlation of light and electron microscopic and immunohistochemical findings with the systemic and ocular findings is presented to emphasise the aggressiveness of MTC in MEN IIB. Clinicopathological correlation was obtained by examining the eyes post mortem. RESULTS AND CONCLUSIONS: Three new findings in MEN IIB have been established by this study. The enlarged corneal nerves can now be regarded as ganglioneuromas. Medullary thyroid carcinoma metastases were found in the choroid. Light and electron microscopic examination of the eye showed ganglioneuromas of the nerves in the limbus, trabecular meshwork, uveal tract and posterior ciliary nerves; this finding may account for the glaucoma occasionally seen in patients with MEN IIB.

Characteristics of an established retinoblastoma cell line HXO-Rb44.

PURPOSE: To study the retinoblastoma cell culture and to establish a new retinoblastoma cell line. METHODS: 22 retinoblastomas were cultured by using the method of single cell suspension. Characteristics of the cultured cells were studied in the following programs: tumor cell morphology in vitro, electron microscopic, growth curve, cloning in soft agar, immunohistochemistry, karyotype and tumorigenicity. RESULTS: 22 retinoblastomas were cultured successfully in vitro, only a continued cell line HXO-Rb44 was established (more than 3 years). The characteristics of this cell line are that it grew as a suspension of round cell in graps like clusters in vitro, its population doubling time was 44 hours, and it could be cloned in soft agar. Histopathologic and ultrastructured pictures showed the characteristics of Rb. HXO-Rb44 cell was positive to NSE and negative to GFAP in immunohistochemical staining. A subcutaneous injection of HXO-Rb44 cells produced a retinoblastoma in BALB/C athumic nude mice. CONCLUSIONS: HXO-Rb44 has the characteristics of retinoblastoma and is a new retinoblastoma cell line. It is a useful material for study this tumor both in basic and clinical fields.