The Diagnostic Usefulness of Electron Microscopy Investigation of Orbital Embryonal Rhabdomyosarcomas

The ultrastructural study of three malignant orbital tumors, only one of which was correctly diagnosed as embryonal rhabdomyosarcoma upon histologic examination, is reported. In all 3 cases electron microscopic investigation revealed the presence of rhabdomyoblasts. These were easily recognizable in one case in which the diagnosis was made on the basis of the optical microscopic study. The other two cases needed further tests to evince rhabdomyoblasts. The importance of an ultrastructural study for a histogenetic characterization of this kind of tumor is emphasized. As far as embryonal rhabdomyosarcomas are concerned, the electron microscopic study is possible, and it gives useful results even when material fixed with routine histologic methods (formalin, Bouin's solution) are used.

Granular Cell Tumor of the Eye (Myoblastoma): Ultrastructural and Immunohistochemical Studies

The clinical and pathological characteristics of a myoblastoma of the orbital are described. The tumor presented as a painless hard mass in the left orbit of a 56-year-old caucasian male, causing diplopia and hypertrophy of the left eye in the primary visual position. Light microscopy studies revealed a typical granular cell tumor with PAS-positive intracytoplasmic granules. Immunoperoxidase studies showed positivity for S-100 protein and desmin. Electron microscopy studies showed numerous intracellular myelin degenerative bodies. The patient developed an epidermoid cyst at the site of initial surgery, but has no signs of local or distant disease two years after initial treatment.

July 2002: 66-year-old female with a one-year history of progressive left proptosis

The July 2002 Case of the Month (COM). This 66-year-old Caucasian female presented with gradually increasing protrusion of her left eye over a one-year period. She complained of increased tearing and foreign body sensation. The physical examination revealed a visual acuity of 20/20, normal color testing, full vision field with motility of her left eye limited in lateral gaze. Pupils were round, symmetric, with no afferent pupillary defect noted. On external examination, her left eye was grossly proptotic with resistance to retropulsion. She had 4 mm proptosis of the left eye. Computed tomography and MR imaging demonstrated a left retro-orbital mass with gadolinium enhancement and focal remodeling of orbital bones. She underwent surgical resection of tumor with a diagnosis of solitary fibrous tumor, and postoperatively she was symptom free. The histopathological differential diagnoses of spindle cell neoplasms of the orbit are discussed. Five months after surgery, no evidence of tumor recurrence was seen on neuroimaging and her vision was 20/20.

Isolated neurofibroma of the orbit with extensive myxoid changes: a clinicopathologic study including MRI and electron microscopic findings

Isolated orbital neurofibroma (INO) without systemic neurofibromatosis is rare. Previous reports including MRI with elaboration of the ultrastructural features of the cellular and extracellular components in INO do not exist. A 44-year-old male presented with painless, slowly progressive proptosis (6 mm) and downward displacement (3 mm) of the left eye of two years duration. MRI revealed a suprabulbar mass hypointense to fat, isointense to brain on T1-weighted images with small hyperintense areas following contrast enhancement. T2-weighted images showed a predominantly hyperintense mass with a few hypointense islands. The lesion was excised using an anterior superior transseptal orbitotomy. Histopathologically, large areas of a paucicellular myxoid stroma containing mucopolysaccharides made up approximately three-quarters of the mass. Focal hypercellular areas showed marked collagen deposition. Blood vessels were distributed at the periphery of the lesion and in association with nodules of nerve sheath cells. Ultrastructurally, perineural and fibroblast-like cells were loosely arranged in a myxoid stroma. Schwann cells were embedded in a dense collagenous matrix. Variable differentiation of Schwann cells, perineural cells and fibroblast-like cells associated with a more solid (collagenous) or loose (myxoid) extracellular matrix may determine the characteristic, though not specific, MRI features in isolated neurofibromas of the orbit.

Giant cell angiofibroma of the orbit and eyelid

PURPOSE

To report the clinicopathologic features of a newly recognized tumor, giant cell angiofibroma.

DESIGN

Observational case series.

MAIN OUTCOME MEASURES

Clinical and histopathologic features of giant cell angiofibroma.

METHODS

Light and electron microscopy and immunohistochemistry of five cases of giant cell angiofibroma.

RESULTS

A total of five patients (4 women and 1 man) are described: two presented with a painless mass in the eyelid, two with a mass in the orbit, and one presented with a conjunctival lesion. All lesions were well demarcated with no capsule and were composed of blood vessels, a patternless spindle-shaped cell proliferation with a solid and pseudovascular appearance, and multinucleated giant cells. Both spindle-shaped and giant tumor cells were intensely positive for CD34 and vimentin.

CONCLUSION

Giant cell angiofibroma resembles solitary fibrous tumor and giant cell fibroblastoma and should be considered in the differential diagnosis of spindle-cell tumors in the eyelid, orbit, and conjunctiva.

Malignant fibrous histiocytoma of the lateral wall of the orbit

A 58-year-old male presented with malignant fibrous histiocytoma originating from the lateral wall of the orbit, manifesting as left exophthalmos and diplopia on left lateral gaze. Magnetic resonance (MR) imaging demonstrated the tumor extending into the left orbit and under the temporalis muscle. The tumor was isointense with muscle on T1-weighted MR images and was surrounded by a low-intensity rim, which was proved to be the capsule after histological examination. The tumor was completely removed after detaching the lateral orbital rim and zygomatic arch using the dismasking flap method. He underwent one course of CYVADIC chemotherapy and has demonstrated no recurrence for 1 year and 6 months postoperatively.

Solitary fibrous tumor of the nasal cavity and orbit

Solitary fibrous tumors (SFT) are rare spindle cell neoplasms generally associated with the serosal surface, especially the pleura. Two SFT are reported arising in the nasal cavity and orbit, occurring in a 33 year old female and a 21 year old male, respectively. The lesions lacked the characteristic features of other recognized neoplasms that occur in these regions. Immunohistochemically, the tumors cells were diffusely and strongly positive for vimentin and CD34 and some or many tumor cells expressed neuron-specific enolase and Leu-7. Ultrastructurally, the tumor cells showed no distinct features although they were suggested to be primitive mesenchymal or fibroblast-like cells. Both tumors were diploid by flow cytometry. The two patients have had benign clinical courses with limited follow-up. Our findings suggest that SFT is of mesenchymal cell origin and support another location for SFT, indicating additional evidence against mesothelial origin. SFT should be included in the differential diagnosis of spindle cell tumors arising in the nasal cavity and orbit.

Spontaneous intraorbital hematoma mimicking orbital neoplasm--case report

A 66-year-old female presented with spontaneous intraorbital hematoma manifesting as left exophthalmos after left eye discomfort persisting for 5 months. She had no history of head injury. Computed tomography revealed a round mass in her left orbit which was slightly high density with no postcontrast enhancement. A blood cyst was extirpated through frontotemporal craniotomy. Histological findings showed no tumor or vascular anomaly. Spontaneous intraorbital hematoma with insidious symptoms is extremely rare and should be considered in the differential diagnosis of orbital mass lesions.

Primary post-traumatic intraorbital meningioma

Intraorbital meningiomas are uncommon tumours that usually represent extension from a primary intracranial tumour. Trauma has been proposed by Cushing and Eisenhardt as an etiologic factor in the development of meningioma following head injury. We report a case of primary post-traumatic intraorbital meningioma and discuss its pathogenesis and management.

Solitary fibrous tumor of the orbit

We report three cases of an orbital soft tissue lesion that fulfills the histologic, immunohistochemical, and electron microscopic criteria for solitary fibrous tumor, an entity previously described as a pleural tumor, but recently reported to occur in other locations. All three patients presented with proptosis. Two of the patients were cured by simple excision, and one patient had two recurrences, the last recurrence incompletely excised. The findings indicate that solitary fibrous tumor can occur in the orbit and, like solitary fibrous tumors of other anatomic sites, may behave in a nonaggressive or occasionally, locally aggressive fashion, with as yet no metastatic potential demonstrated in orbital lesions.

Leiomyosarcoma of the orbit: diagnosis of its recurrence by fine-needle aspiration cytology

An 8 1/2-yr-old boy with proptosis was diagnosed to have low-grade leiomyosarcoma of the orbit following lateral orbitotomy and histology of an incompletely excised intraconal mass. He received chemotherapy but had recurrence of proptosis at the age of 12 yr. Ultrasonography revealed a solid mass and its fine-needle aspiration cytology features were consistent with recurrence of leiomyosarcoma. A year later, the cytodiagnosis was confirmed by histology of the excised tumor from a second lateral orbitotomy. Masson's trichrome stain confirmed the smooth muscle nature of the neoplasm and ultrastructural features were in favor of leiomyosarcoma. The patient received intermittent chemotherapy, and is clinically free from disease at the age of 17 yr.

Primary malignant ectomesenchymoma of the orbit

Malignant ectomesenchymoma (MEM) is a rare soft tissue tumour believed to arise from a pluripotential migratory neural crest cell and composed of both a mesenchymal element (most often rhabdomyosarcoma) and a neuroectodermal element (often neuroblastoma). Reported sites of origin are the abdomen, perineum or scrotum, the extremities, the middle ear, nasopharynx, face, and neck. We report the first case of an orbital MEM, with a review of the 17 cases previously reported from other sites.

Intraocular and orbital malignant schwannomas in F344 rats

Intraocular and orbital malignant Schwannomas in two F344 rats are presented. The two Schwannomas were identified among approximately 60,000 male and 60,000 female F344 rats. The intraocular malignant Schwannoma occurred in the iris, invading the corneal stroma through the destroyed Descemet membrane. The malignant orbital Schwannoma occurred in the left orbit, invading the contralateral orbit along the optic nerve. Histologically, the intraocular Schwannoma consisted predominantly of a perivascular fascicular pattern of plump spindle cells associated with marked cytoplasmic vacuolization. The orbital Schwannoma consisted of Antoni type A and B pattern, but Antoni B tissues predominated. Antoni A tissues consisted of closely packed, elongated spindle cells arranged in interlacing fascicles, while Antoni B tissues were highly cellular and consisted of anaplastic, small cells associated with marked cyst formation. Immunohistochemically, the intraocular Schwannoma had a positive immunoreactivity for S-100 protein, while the orbital Schwannoma had a negative immunoreactivity. Ultrastructurally, the cells of both intraocular and orbital Schwannomas had long, thin cell processes and pericytoplasmic basal laminae. Particularly, the plump spindle cells of the intraocular Schwannoma were most strikingly characterized by the well developed, extremely attenuated cell processes arranged in a lamellar or spiral pattern. These cell processes and cell bodies were associated with numerous desmosomes. Intracytoplasmic filamentous granules and bodies, consisting of intermediate filaments approximately 7 nm in width, were additional characteristics of the plump spindle cells.

Orbital squamous cell carcinoma after retinal detachment surgery

We report on a 76-year-old patient with a squamous cell carcinoma of the left orbit. The tumour had no connection with the conjunctiva but was located at the site of an encircling band which had been inserted 13 years before. A major part of the tumour presented as a well circumscribed solid mass within the extraocular tissues next to the inferior equator, but the exenteration specimen also showed tumour extension within the adjacent choroid. Histological examination showed a well differentiated keratinising squamous cell carcinoma with numerous mitotic figures and many epithelial pearls. A thorough examination in search of a primary carcinoma of the lacrimal gland or the sinus, with invasion into the orbit, or an epithelial neoplasm elsewhere suggestive of metastatic disease into the choroid did not reveal any specific pathological findings. Thus the most probable origin of the tumour seems to be epithelium which had been misplaced during retinal detachment surgery and had subsequently undergone malignant transformation.

Poorly differentiated primary orbital sarcoma (presumed malignant rhabdoid tumor). Radiologic and histopathologic correlation

A 47-year-old man presented with acquired hyperopia and gaze-evoked visual loss. Computed tomography and magnetic resonance imaging demonstrated a well-circumscribed intraconal tumor. Histopathologic studies indicated that the tumor was a poorly differentiated primary orbital sarcoma compatible with malignant fibrous histiocytoma or malignant rhabdoid tumor. To our knowledge, no case of primary orbital malignant rhabdoid tumor has been previously described in an adult.

Juvenile fibromatosis of the orbit: a case report with review of the literature

Proliferation of fibrous tissues to form a localised mass with infiltrating margins may occur anywhere in the body; involvement of the orbit is rare. Children and young adults are most commonly affected. The term 'juvenile fibromatosis' is one of several synonyms. Of the two main forms of this entity, the solitary form is the more common and the prognosis is good. The multicentric form has a poor prognosis. The patients described, a 2 1/2-year-old boy, had a solitary nodule of juvenile fibromatosis removed from the right orbit and was asymptomatic 2 3/4 years postoperatively.

Granular cell tumours of the orbit

Granular cell tumours are uncommon benign tumours, occurring in various sites in the body, and very rarely in the orbit or ocular adnexa. Four cases of orbital granular cell tumour are described, with detailed light and electron microscopic description of one tumour arising in the orbital apex of a child. The histogenesis of granular cell tumour is uncertain, with many authors proposing an origin from Schwann cells. In central nervous system granular cell tumours, an astrocytic cell origin has been proposed. Evidence is presented for an origin from astrocytes in a child whose tumour arose in or adjacent to the optic nerve.

Orbital intramuscular schwannoma

In an 8-year-old girl with asymptomatic proptosis, computed tomographic scans showed a large medial orbital mass that contoured the globe anteriorly, bowed the optic nerve laterally, and extended posteriorly to the orbital apex. T1-weighted coronal magnetic resonance images showed the mass to be a diffusely enlarged medial rectus muscle. Histopathologic examination of a medial rectus muscle biopsy specimen disclosed a multinodular, intramuscular schwannoma, separating and infiltrating normal skeletal muscle fibers. The intramuscular location and multinodular configuration of this tumor, together with its occurrence in a child, distinguish it from previous orbital schwannomas.

Orbital cysticercosis--an ultrasonic diagnosis

Ocular cysticercosis, a platyhelminth infection, involves various ocular and adnexal sites. Orbital cysticercosis is a relatively rare site of presentation. We illustrate that this parasitic cyst, when present in the orbit, mimics an orbital pseudotumour. We have used ultrasound as an effective pre-operative diagnostic modality.

Melanotic schwannoma of the orbit. Immunohistochemical and ultrastructural study of a case and survey of the literature

Light microscopical, immunohistochemical and ultrastructural study of a case of melanotic (pigmented) schwannoma in the left orbit of a 22-year-old man is presented. The tumour caused exophthalmus for three months and was located under the eyeball. Partial removal resulted in recurrence after three years. The recurrent tumour with extension to the nasal cavity and maxillary sinus was extirpated without loss of vision, and a year later the patient was without symptoms. The tumour tissue was Fontana positive, could be bleached, and showed immunoreactivity for S-100, vimentin and HMB 45. Ultrastructurally, the tumour cells, particularly the pigment loaded cells, showed a varying amount of basal lamina at the surface, melanosomes in varying stages of melanization, fine cytoplasmic filaments and micropinocytotic vesicles. Survey of the literature and discussion of the melanogenesis in Schwann's cells are presented.

Fine-needle aspiration cytology of malignant hemangiopericytomas with ultrastructural and flow cytometric analyses

A hemangiopericytoma (HPC) is an uncommon soft-tissue neoplasm that may arise in many body sites. The cytologic features of fine-needle aspirates (FNAs) of HPCs have only rarely been described in the literature. We examined FNAs of malignant HPCs from the head and neck region (three) and the retroperitoneum (one) in four adults (aged 38 to 83 years). All four FNAs yielded cellular specimens that consisted of uninuclear tumor cells with high nuclear-cytoplasmic ratios. The cytomorphological spectrum included nuclei that were oval to elongate and had very finely granular, evenly distributed chromatin with one or two small but distinct nucleoli. Hemangiopericytomas yield aspirates that may be considered malignant and may suggest sarcoma. Histologically, all four neoplasms manifested high mitotic activity. The ultrastructural features of all four tumors were supportive of the diagnosis of HPC. Although a specific primary diagnosis of HPC on FNA of a soft-tissue mass is unlikely, cytologic analysis may allow diagnosis of recurrent or metastatic HPC. We were able to perform flow cytometric determinations of tumor DNA content on three of the resected neoplasms. In two, an aneuploid pattern was found, including the neoplasm with the most marked pleomorphism in the FNA. The third was diploid.

A clinicopathologic study of three carcinoid tumors metastatic to the orbit. Immunohistochemical, ultrastructural, and DNA flow cytometric studies

Three patients with histopathologically proven orbital metastatic lesions from a carcinoid tumor are reported. Computed tomography (CT) disclosed a well-circumscribed orbital mass in two of three cases. Each tumor was studied by both light and electron microscopy as well as immunohistochemistry and DNA flow cytometry. A review of the literature discloses the relatively rare occurrence of carcinoid tumors metastasizing to the eye and orbit. With the exception of one case, the reported metastatic carcinoid tumors to the uvea all developed from primary bronchial carcinoids. In contrast, the vast majority of the reported orbital metastases arose from ileal carcinoids. Immunohistochemical markers such as chromogranin A, synaptophysin, and serotonin have proven to be useful diagnostic tools in evaluating carcinoid tumors. Furthermore, DNA flow cytometry may be of prognostic value in patients with metastatic carcinoid tumor.

[Light and electron microscopic study of orbital cavernous hemangioma]

We examined the specimens of tumors from three patients with orbital cavernous hemangioma by light and electron microscopy. The tumors mostly consisted of many vessels of various sizes. A part of the tumor tissues showed irregular vascular inner spaces like sinusoids. Apart from the sinusoid-like vessels, we divided the other vessels into 10 groups at every 100 microns-interval based on the difference of the inner diameter and measured the maximum and minimum width of the media. The average maximum width increased until the inner diameter reached 300-400 microns, while the average minimum width increased until it reached 200-300 microns. In groups with greater inner diameter, the average maximum and average minimum widths were approximately constant. There were three kinds of vessels: vessels of cuboid endothelia, of flat endothelia, and of both cuboid and flat endothelia. The width of media of the vessels having cuboid and flat endothelia was greater than that of the other types of vessels. The lamina densa of endothelia was broken or stratified. Myofibroblast-like cells proliferated among the vessels and could not be distinguished from tumor cells of hemangiopericytoma. These results indicate that smooth muscle cells proliferate by an unknown mechanism and proliferation is associated with changes of endothelia in cavernous hemangioma, and strongly suggest that this tumor is hamartoma.

Melanotic paraganglioma of the orbit: a case report

A paraganglioma of the orbit in a 21-year-old woman is presented, containing oculo-cutaneous melanin in many tumor cells, occasionally adjacent to neurosecretory granules, and in macrophages. This tumor expands the list of neuroectodermal tumors with potential melaninization.

Malignant rhabdoid tumor of the orbit

Malignant rhabdoid tumor (MRT), originally described as a sarcomatous variant of Wilms' tumor, is now recognized as a distinct, highly malignant entity. The authors describe, for the first time, a primary tumor of the orbit with histologic, immunohistochemical, and ultrastructural features of MRT. Their findings suggest both epithelial and mesenchymal differentiation of this unique tumor.

Primary orbital neuroblastoma

A 35-year-old man had a primary neuroblastoma of the left orbit. Histopathologically, the tumor was composed of uniform small round cells containing argyrophilic granules arranged in nests and cords with pseudorosettes, Homer-Wright rosettes, and a fine fibrillary background matrix. Immunohistochemical staining for chromogranin was positive. Electron microscopy showed small (108- to 173-nm) dense core granules. Eight years after surgery and radiation therapy the patient was free of local recurrence and metastases. To our knowledge, primary orbital neuroblastoma has been reported only once previously. Neuroblastoma, which occurs most frequently in children and has an incidence in the United States of 500 cases annually, is a distinctly unusual tumor in adults.

Primary malignant melanoma of the orbit arising in a cellular blue naevus

Primary malignant melanoma of the orbit is a rare clinical entity. We report the clinical course and present the light and electron microscopic findings in a case arising in a cellular blue naevus. While most orbital melanomas are associated with a naevus of Ota, there was no clinically visible abnormal pigmentation in our patient. The possible origin of the tumour cell and its ultrastructural features are discussed.

Mucoepidermoid carcinoma of the lacrimal gland fossa: confirmation by ultrastructural study

We have described a patient with a biopsy-proven mucoepidermoid carcinoma of the orbit. Although it may have represented a metastasis from a malignancy of the upper respiratory tract, clinically it appeared to be a primary neoplasm of the lacrimal gland. This case emphasizes the value of transmission electron microscopy in diagnosing poorly differentiated orbital tumors.

Maxillo-orbital lymphoma (Burkitt's-type) in an infant Macaca fascicularis

A 5-month-old male cynomolgus monkey (Macaca fascicularis) with facial deformation and proptosis of the left eye was euthanized due to a rapidly-growing peribulbar and retro-orbital mass. The mass invaded the soft tissue behind the right eye and extended ventro-medially through the lacrimal, ethmoid, maxillary and frontal bones. Caudo-dorsal extention of the mass through the left frontal bone and into the meninges and parenchyma of the frontal cerebral lobe was observed. Histologically, the cell population making up the mass was variable, but most of the neoplastic cells were blast-like with a large central round to ovoid nucleus, active coarsely stippled euchromatic chromatin, 1-4 prominent nucleoli and sparse cytoplasm. Interspersed between these neoplastic lymphocytes were numerous aberrant mitoses and histiocytes with foamy cytoplasm producing a "starry-sky" pattern. Cells further away from the central neoplastic core and closer to fragmented bone surfaces had plasmacytoid features with an eccentric hyperchromatic nucleus and abundant eosinophilic cytoplasm. Electron microscopy confirmed the formentioned cell types. Morphometric analysis of tumor cell indicated similarities to cells of human Burkitt's lymphoma. The tumor cells indicated similarities to cells of human Burkitt's lymphoma. The tumor was diagnosed as a malignant lymphoma of unknown etiology, similar to those seen in African children with Burkitt's lymphoma.

Primary Ewing's sarcoma of the orbit presenting with visual loss

A case of primary Ewing's sarcoma of the orbit and paranasal sinuses in a 6-yearold boy is reported. The child presented with headaches and unilateral visual loss. Loss of vision as a result of optic nerve involvement with primary Ewing's sarcoma is extremely rare.

Infantile subconjunctival and anterior orbital fibrous histiocytoma. Ultrastructural and immunohistochemical studies

A fleshy, polypoidal and partially lobulated lesion that protruded between the eyelids from the medial caruncular region and that infiltrated the contiguous anterior orbital tissues developed over 1 month in a 9-month-old infant. The microscopic features of the tumor included a plump spindle cell population, more polygonal cells, early xanthoma cell transformation, infiltrating lymphocytes and eosinophils, and multinucleated giant cells, the last not exhibiting classic Touton characteristics. The histopathologic differential diagnosis ranged among fibrous histiocytoma, juvenile xanthogranuloma, and eosinophilic granuloma (histiocytosis-X). Results of electron microscopy disclosed abundant rough-surfaced endoplasmic reticulum, a paucity of lysosomes, and no Langerhans' (Birbeck) granules. Immunohistochemistry corroborated the fibrohistiocytic nature of the tumor, because histochemical stains for the enzymes alpha-1-antichymotrypsin and lysozyme, and monoclonal or polyclonal antibodies against common leukocytic antigen and S-100 protein, were negative--whereas they would have been expected to be positive in various combinations in the different histiocytic proliferations. Vimentin was identified in the tumor cells; this is an intermediate cytoplasmic filament almost always present in mesenchymal proliferations. The distinctions between fibrous histiocytomas of stromal cell origin and true histiocytic proliferations of bone marrow cell provenance are explored.

Orbital T-cell lymphoma in human T-cell leukemia virus-I infection

This is the first report of orbital involvement in systemic adult T-cell leukemia/lymphoma (ATLL). The etiologic agent of ATLL is the human T-cell leukemia virus-I (HTLV-I), the first retrovirus demonstrated to induce cancer in humans. The diagnosis of ATLL is based on characteristic clinicopathologic features in combination with serologic or virologic evidence of HTLV-I infection. Serum antibodies to HTLV-I were identified by immunofluorescent microscopy. Viral particles characteristic of HTLV-I were found in a culture of the patient's peripheral blood lymphocytes. The patient was a native of the Caribbean, one of the known endemic foci of HTLV-I infection. Adult T-cell leukemia/lymphoma should be considered in the differential diagnosis of orbital T-cell lymphomas.

Orbital metastasis from a carcinoid tumor. Computed tomography, magnetic resonance imaging, and electron microscopic findings

An otherwise asymptomatic 63-year-old woman with a history of a carcinoid tumor of the ileum and a cutaneous melanoma of the shoulder developed unilateral proptosis. Orbital ultrasonography, computed tomography, and magnetic resonance imaging revealed a large, well-circumscribed orbital mass involving the superior rectus muscle. The surgically excised tumor was studied by light microscopy, histochemistry, and transmission electron microscopy. These studies confirmed the diagnosis of carcinoid tumor. The clinical and pathologic features of this rare type of orbital metastasis are discussed.

Granular cell tumor of the orbit and ocular adnexae

Although granular cell tumor (GCT) has been a distinct pathological entity since 1926, confusion and controversy have long existed regarding the nature and histogenesis of the tumor. Twenty-five cases of granular cell tumor involving the orbit and ocular adnexae previously reported in the ophthalmic literature, are reviewed and six additional cases are reported. The histopathological and immunohistochemical characteristics of granular cell tumors in this uncommon location are discussed and their probable origin from Schwann cells is also considered.

Primary differentiated neuroblastoma of the orbit

A 49-year-old woman had a 12-year history of a localized left orbital tumor that required five subtotal excisions, orbital radiotherapy, and finally an exenteration. The last procedure was performed after visual function had deteriorated and in order to prevent spread of the tumor into a surrounding compartment. The biopsy specimens from the first four surgeries showed a stroma-free spindle cell tumor with benign cytologic features and no mitotic activity, which exhibited palisading of nuclei, imbrication of delicate cytoplasmic processes (neuropil), true perivascular rosettes with cytoplasmic processes oriented perpendicular to vessel walls, and Wright rosettes. The biopsy after radiotherapy and the exenteration specimen contained more polyhedral (gemistocytoid) tumor cells with abundant eosinophilic cytoplasm and tapering cell processes; nuclear pleomorphism without mitotic activity was also seen. Electron microscopy showed the presence of neurosecretory dense-core granules in the perikaryon region of the tumor cells and in the myriad interweaving cytoplasmic processes (neurites); neither Nissl substance nor synapses were identified. Immunohistochemical staining for neuron-specific enolase was positive, but glial fibrillary acidic protein stained negative. This previously undescribed orbital tumor is interpreted as a primary differentiated neuroblastoma without evidence of ganglion cell differentiation that exhibited locally aggressive behavior. The distinctions between neuroblastic and neuroendocrine tumors are discussed.

Infiltrating orbital granular cell tumour: a case report and literature review

A surgical biopsy of an infiltrative retrobulbar mass in a 44-year-old man was diagnosed as granular cell tumour. Electron microscopy and immunoperoxidase stains were used to confirm the diagnosis and to study the histogenesis of this rare soft tissue neoplasm. S-100 stain was positive, while neuron-specific enolase and myoglobin stains were negative, suggesting a non-specific neural origin for the cells. The capability of this tumour to invade surrounding tissues has seldom been described in the orbit and is demonstrated by this case.

Signet-ring cell lymphoma in the orbit: a case report and review

The authors report on the first case of signet-ring cell lymphoma involving the orbit. This variant of non-Hodgkin's lymphoma contains either vacuolated or eosinophilic cytoplasmic inclusions that squeeze the nucleus to one side of the cell. In this case, the inclusions were eosinophilic and stained positively for PAS, immunoglobulin M (IgM) heavy chain and kappa light chain. Electron microscopy showed granular electron-dense material trapped within distended loops of rough endoplasmic reticulum. Twenty-two cases of signet-ring cell lymphoma previously reported elsewhere in the body are reviewed, and their clinical significance is discussed.

Ectopic brain in the orbit

We report a case of ectopic brain tissue in the orbit associated with a bony defect of the orbit and the presence of skeletal muscle. Previous reports of orbital ectopic brain and related lesions in the orbit and at other sites are reviewed.

Large cell lymphoma of the orbit with microvillous projections ('porcupine lymphoma')

A 57-year-old man had a diffuse mass in the lacrimal gland area associated with extensive bony destruction. A malignant epithelial tumor of the lacrimal gland was suspected clinically, and a biopsy specimen disclosed an undifferentiated malignant neoplasm of uncertain origin. Ultrastructural studies, however, revealed features of a lymphoid tumor with myriad cytoplasmic microvillous projections. The patient has had no evidence of systemic lymphoma after more than three years of follow-up. To our knowledge, this is the first report of orbital involvement of a large cell lymphoma with microvillous projections ("porcupine lymphoma"). The role of electron microscopy in the differential diagnosis of this orbital tumor was important, since epithelial tumors of the lacrimal gland are best managed by surgical excision, whereas lymphoid tumors usually respond satisfactorily to radiotherapy.

Epithelioid angiosarcoma of the orbit presenting as Tolosa-Hunt syndrome. A clinicopathologic case report with review of the literature

The clinical diagnosis of Tolosa-Hunt syndrome was first considered in a 66-year-old man with facial pain and diplopia. A complete neuroradiologic evaluation as well as an oncologic work-up yielded normal results. Several courses of oral prednisone provided no significant benefit. Within a year the patient became clinically worse and a CT scan disclosed an abnormal area of enhancement at the left orbital apex. An orbital exploration was performed elsewhere and a histologic diagnosis of myositis was obtained. Because of further worsening the patient was re-evaluated 3 months later and a CT scan showed a mass in the left orbital apex and superior orbital fissure. A second orbital exploration was performed and a sausage-shaped mass encompassing the optic nerve was excised. By light microscopy a poorly differentiated malignant tumor was infiltrating the orbital tissues with areas of intra- and perineural invasion. The tumor cells were arranged in strands and tubules with a definite tendency to form lumens that often contained red blood cells. Electron microscopic studies disclosed features consistent with a neoplasm of endothelial cell origin displaying a polarized basal lamina and rare micropinocytotic vesicles on the luminal side. The presence of multiple, slender microvilli and sometimes tonofilaments as well as desmosomes were interpreted as epithelioid metaplasia of an angiosarcoma.

Benign peripheral nerve sheath tumors (neurofibromas) of the lacrimal gland

Two patients, a 43-year-old woman and a 62-year-old man, developed benign peripheral nerve sheath tumors (neurofibromas) of the lacrimal gland, in the former case of the deep orbital lobe, and in the latter of the palpebral lobe. A neurogenic tumor was not seriously considered clinically in either case, because of the paucity of previous reports on the occurrence of neural tumors in the lacrimal fossa region. Instead, in the first case a benign mixed tumor was considered the most likely clinical diagnosis, whereas in the second the coexistence of a swelling in the parotid gland raised the possibilities of a lymphoid tumor or a leukemia. Due to unusual light microscopic features, transmission electron microscopy was required to secure unequivocal diagnoses. In the orbital lobe tumor, an encapsulated spindle cell proliferation without nuclear palisading but with focal areas of myxoid change suggested either a cellular benign mixed tumor or a schwannoma. The palpebral lobe lesion displayed a myxoid spindle cell proliferation that had splayed apart the ducts and acinae of the lacrimal gland, to impart the overall appearance of a benign mixed tumor. The ducts, however, were multilaminar rather than possessing the usual double cellular layer seen in classical benign mixed tumors, and the glandular units contained zymogen granules, which are typically not seen in benign mixed tumors. Electron microscopy disclosed in both lesions the presence of interrupted basement membrane material partially surrounding the tumor cells, long spacing collagen (banded basement membrane material), and poorly developed desmosomes, features compatible with a neural tumor. Neither myofilaments, tonofilaments, nor ductal-type granules sometimes observed in benign mixed tumors were discovered. The tumor cells in these cases therefore failed to demonstrate clear-cut Schwann cell characteristics (eg, continuous basement membranes, pseudo-mesaxons, tangles of cell processes), and more closely resembled perineural cells that have been described in ultrastructural studies of peripheral nerve tumors including neurofibromas of other sites.

Postradiation leiomyosarcoma of the orbit complicating bilateral retinoblastoma

A 31-year-old woman had bilateral retinoblastoma diagnosed in early childhood. The right eye was enucleated at the age of 1 year, and the left eye was treated with radiation therapy (a total dose of 16,000 rad). Twenty-three years later, in 1975, a subcutaneous mass was noted in the left periorbital region. A biopsy specimen of the mass was taken and a diagnosis of pleomorphic postradiation sarcoma was made. Electron microscopic studies of the periorbital mass confirmed the diagnosis of leiomyosarcoma. After additional radiation therapy, the residual mass was surgically excised. Five years later, a right renal mass, which histologically proved to be a renal cell carcinoma, was discovered. She was treated with nephrectomy, radiation, and chemotherapy. A recent follow-up examination disclosed that the patient is alive and apparently without any evidence of metastatic disease, 30 years after the diagnosis of bilateral retinoblastoma was made. The literature is reviewed regarding postradiation sarcomas and the occurrence of second malignant neoplasms in patients with retinoblastoma.

Primary carcinoid tumor of the orbit. A clinicopathologic study with histochemical and electron microscopic observations

A patient with a primary carcinoid tumor of the orbit is described. No other tumor had been found during the 15-year interval since the onset of unilateral proptosis. Symptoms of the carcinoid syndrome were absent, and the urinary levels of 5-hydroxyindoleacetic acid were normal. Histologically, the bulky, noninfiltrating tumor compressed but did not invade the optic nerve. The argyrophilic cells were arranged in solid lobules and formed abundant, rosettelike structures. Pleomorphic neurosecretory granules were demonstrated by transmission electron microscopy.

Juvenile fibrosarcoma of the orbit and eyelid. A study of five cases

Five patients had juvenile fibrosarcoma of the orbit and eyelid. At initial surgical intervention, the patients ranged in age from newborn to 8 years (mean, 3 years 9 months). Three patients were male and two were female. Proptosis and/or painless swelling of the eyelid were the most common signs and symptoms. Four tumors grew within a few weeks or months, and all five were poorly circumscribed. They were composed of immature, spindle-shaped fibroblastic cells in a classic herringbone pattern or in interlacing fascicles. Hypercellularity and mitotic activity were present in all lesions. The differential diagnosis included rhabdomyosarcoma, fibromatosis, and fibrous histiocytoma. Electron microscopy confirmed the fibroblastic nature of the tumor cells in three cases. Follow-up ranged from one to 32 years (median, seven years). Two of five tumors recurred locally but none metastasized. Apparently surgical excision is the treatment of choice and the tumor has a favorable prognosis.

Alveolar soft-part sarcoma of the orbit: a clinicopathologic analysis of seventeen cases and a review of the literature

This is a clinicopathologic study of 17 cases of alveolar soft-part sarcoma of the orbit. The mean age of patients was 23 and the median was 18 (range, 11 months to 69 years); 13 patients (76.5 per cent) were women and four were men (ratio, 3.25:1). The right and left orbits were equally involved (eight patients each), and in one the laterality was not specified. Histologically, the tumors had a distinctive organoid pattern outlined by thin-walled capillaries and were composed of nests of large polyhedral cells with abundant, finely granular, acidophilic cytoplasm. Approximately two thirds of the tumors had diagnostic PAS-positive diastase-resistant crystalline structures. Histologically, the differential diagnosis included nonchromaffin paraganglioma, granular cell tumor, metastatic renal cell carcinoma, vascular tumor, alveolar rhabdomyosarcoma, and amelanotic malignant melanoma. Electron microscopic studies of one tumor disclosed mitochondria with abnormal cristae, increased amounts of glycogen, and cytoplasmic crystalline structures with a periodicity of 8 to 10 nm. Smaller membrane-bound electron-dense granules appeared to be precursors of the crystals. Follow-up studies showed that eight patients were alive and well (median follow-up period, 11.4 years). Six of the eight patients at the time of diagnosis were 20 years of age or younger. A ninth patient was alive and well 13 years after excision of the orbital mass and four years after bilateral thoracotomy with resection of nine pulmonary nodules. Two patients died as a result of metastatic disease, one 14 years and the other 21 years after initial orbital surgery. Two patients died of other causes, one of whom had pulmonary metastases at autopsy. The follow-up period on two recent cases was less than three years, and two patients were lost to follow-up. The disease pursued an indolent clinical course. Surgery offers the best chance to control the disease.

Primary orbital schwannomas

Seven histologically proved cases of primary orbital schwannoma have been seen at the University of British Columbia Orbital Clinic between September 1976 and December 1980. We describe here their varied clinical presentations, preoperative investigations, operative findings, and appearances on light and electron microscopy. Although no single feature is pathognomonic, a multiplicity of clinical, radiographic, and surgical features point to this lesion. Of preoperative investigations the computed tomography scan was the most helpful, especially in localising the lesion. Of the 7, 4 were intraconal and 3 were extraconal. The surgical approach was dictated by tumour site and included anterior, lateral, and panoramic orbitotomies. At surgery the nerve of origin of 4 of the tumours was identified. All tumours were excised totally or subtotally. There has been no recurrence to date.