Adrenal Schwannoma with Apparent Uptake of Immunoglobulins

Schwannoma, a rare tumor of the adrenal gland, was an incidental finding in a 63-year-old woman who had no endocrine symptoms. In addition to the usual light and electron microscopic and immunohistochemical features of a schwannoma, the tumor contained large granular cells and a stroma rich in lymphocytes and plasma cells. The tumor cells appeared on ultrastructural examination to incorporate proteinaceous material by endocytosis into large lysosomal bodies and on immunocytologic studies; the presence of immunoglobulins was noted within the cytoplasm. The apparent massive uptake of immunoglobulins by tumor cells suggests a direct interaction between host and the tumor.     

Adrenal Schwannoma with Apparent Uptake of Immunoglobulins

Schwannoma, a rare tumor of the adrenal gland, was an incidental finding in a 63-year-old woman who had no endocrine symptoms. In addition to the usual light and electron microscopic and immunohistochemical features of a schwannoma, the tumor contained large granular cells and a stroma rich in lymphocytes and plasma cells. The tumor cells appeared on ultrastructural examination to incorporate proteinaceous material by endocytosis into large lysosomal bodies and on immunocytologic studies; the presence of immunoglobulins was noted within the cytoplasm. The apparent massive uptake of immunoglobulins by tumor cells suggests a direct interaction between host and the tumor.     

Pheochromocytoma Combined with Malignant Schwannoma: Unusual Neoplasm of the Adrenal Medulla

A 38-year-old woman was operated on to remove a large tumor that replaced the left adrenal gland. The tumor was encapsulated and showed small areas typical of pheochromocytoma, and spindle cell or undifferentiated round cell sarcoma in most areas. Metastases of primitive round cell appearance were operated from the abdominal cavity and abdominal wall shortly after the initial surgery. Eighteen months after the first operation, the patient was alive with metastases in liver and retroperitoneal space. The pheochromocytomalike component showed a typical ultrastructural and immunohistochemical profile of pheochromocytoma and was positive for neurofilaments, synaptophy-sin, neuron-specific enolase, and S-100 protein in the sustentacular cells. The sarcomatous areas showed fibroblastoid spindle cells that were often surrounded by a basal lamina. Immunohisto-chemistry revealed S-100 protein positivity in many spindle cells, but markers of pheochromocytoma or epithelial differentiation were absent. The metastases lacked all markers except for vimentin, and the cells were undifferentiated by electron microscopy. These findings suggest that the neoplasm was a compound tumor with a typical pheochromocytoma component and a sarcoma resembling a malignant schwannoma. Neoplastic proliferation of the S-100 protein-positive Schwann-cell-like sustentacular cells of the pheochromocytoma would be an explanation for the genesis of this sarcoma associated with pheochromocytoma.     

Pheochromocytoma Combined with Malignant Schwannoma: Unusual Neoplasm of the Adrenal Medulla

A 38-year-old woman was operated on to remove a large tumor that replaced the left adrenal gland. The tumor was encapsulated and showed small areas typical of pheochromocytoma, and spindle cell or undifferentiated round cell sarcoma in most areas. Metastases of primitive round cell appearance were operated from the abdominal cavity and abdominal wall shortly after the initial surgery. Eighteen months after the first operation, the patient was alive with metastases in liver and retroperitoneal space. The pheochromocytomalike component showed a typical ultrastructural and immunohistochemical profile of pheochromocytoma and was positive for neurofilaments, synaptophy-sin, neuron-specific enolase, and S-100 protein in the sustentacular cells. The sarcomatous areas showed fibroblastoid spindle cells that were often surrounded by a basal lamina. Immunohisto-chemistry revealed S-100 protein positivity in many spindle cells, but markers of pheochromocytoma or epithelial differentiation were absent. The metastases lacked all markers except for vimentin, and the cells were undifferentiated by electron microscopy. These findings suggest that the neoplasm was a compound tumor with a typical pheochromocytoma component and a sarcoma resembling a malignant schwannoma. Neoplastic proliferation of the S-100 protein-positive Schwann-cell-like sustentacular cells of the pheochromocytoma would be an explanation for the genesis of this sarcoma associated with pheochromocytoma.     

Intriguing Case: Pigmented Melanocytie Schwannoma of the Uterine Cervix

A 47-year-old woman had a lesion of the uterine cervix that presented clinically as a protruding or aborted leiomyoma. Grossly the tumor occupied a substantial portion of the cervical and endocervical region. Histologically it showed a spindle cell neoplasm arranged in large fascicles that penetrated deeply into the fibromuscular wall of the cervix. The tumor cells had abundant pink cytoplasm that contained considerable brown melanin granules confirmed by Fontana's stain. Cytologically nuclear pleomorphism, hyperchromatism, and giant nuclear forms were observed. Mitoses were also seen. Localized nuclear palisading was present. Electron microscopic examination of paraffin-embedded material revealed numerous premelanosomes and opaque granules that were compatible with mature melanosomes, thus confirming melanogenesis in the tumor. Tumor cells exhibited focal projections, and the connective tissue showed abnormal spacing of collagen. Basal lamina material was noted focally on tumor cell surfaces. Immunocyto-chemistry showed a positive reaction to S-100 protein and HMB-45 in tumor cell cytoplasm.     

Epithelioid Malignant Schwannoma

A case of epithelioid malignant schwannoma (EMS) is reported. The tumor arose in the left radial nerve at the axillary fossa of a 65-year old male. A few months after resection of the primary axillary tumor, several intrapulmonary metastases appeared. Microscopically, the primary tumor showed highly cellular areas of polygonal or rounded cells, resembling lymphoma or melanoma, while the metastatic tumors revealed cord formation or rows, resembling carcinoma. Immunohistochemical studies showed that some of these tumor cells contained S-100 protein. Ultrastructurally, these tumor cells revealed delicate cytoplasmic projections, which contained bundles of microfilaments. However, the tumor cells did not have melanosomes. Varying amounts of basal lamina material surrounded the tumor cells. From the above features, we obtained a correct diagnosis of EMS. Acta Pathol. Jpn. 32: 195∼202, 1989.     

Neuroblastoma of the Anterior Mediastinum in an 80-Year-Old Woman

A 7-cm anterior mediastinal tumor in an 80-year-old woman was found by light and electron microscopy to be a neuroblastoma. Immunoreactivity for neuron-specific enolase, synaptophysin, and chromogranin supported the diagnosis. Neuroblastoma is an uncommon tumor in adults and we are not aware of a previous report of such a tumor in a patient of this age.     

Diagnostic Problems in Breast Pathology: The Benefit of Ultrastructural and Immunocytochemical Analysis

This report deals with the diagnostic importance of intracytoplasmic lumina. The separation between tubular carcinoma and sclerosing adenosis, and the ultrastructural features of variants of lobular carcinoma are discussed. The role of electron dense granules as well as other markers for neuroendocrine cells are evaluated, and finally, the difficult separation of both small-cell and spindle cell tumors is considered.     

Crystals in a Gastric Schwannoma

A gastric schwannoma containing large numbers of intracytoplasmic crystals is described. The latter are compared with intracytoplasmic crystals found in the cells of other tumors and their nonneoplastic cell counterparts. The extreme morphologic and histochemical heterogeneity of the different types of crystals is emphasized.     

Dopaminergic innervation of interneurons in the rat basolateral amygdala

The basolateral nuclear complex of the amygdala (BLC) receives a dense dopaminergic innervation that plays a critical role in the formation of emotional memory. Dopamine has been shown to influence the activity of BLC GABAergic interneurons, which differentially control the activity of pyramidal cells. However, little is known about how dopaminergic inputs interface with different interneuronal subpopulations in this region. To address this question, dual-labeling immunohistochemical techniques were used at the light and electron microscopic levels to examine inputs from tyrosine hydroxylase-immunoreactive (TH+) dopaminergic terminals to two different interneuronal populations in the rat basolateral nucleus labeled using antibodies to parvalbumin (PV) or calretinin (CR). The basolateral nucleus exhibited a dense innervation by TH+ axons. Partial serial section reconstruction of TH+ terminals found that at least 43-50% of these terminals formed synaptic junctions in the basolateral nucleus. All of the synapses examined were symmetrical. In both TH/PV and TH/CR preparations the main targets of TH+ terminals were spines and distal dendrites of unlabeled cells. In sections dual-labeled for TH/PV 59% of the contacts of TH+ terminals with PV+ neurons were synapses, whereas in sections dual-labeled for TH/CR only 13% of the contacts of TH+ terminals with CR+ cells were synapses. In separate preparations examined in complete serial sections for TH+ basket-like innervation of PV+ perikarya, most (76.2%) of TH+ terminal contacts with PV+ perikarya were synapses. These findings suggest that PV+ interneurons, but not CR+ interneurons, are prominent synaptic targets of dopaminergic terminals in the BLC.     

Neuroendocrine carcinomas: Role of immunocytochemistry and electron microscopy

Neuroendocrine tumors occur in many sites of the body and can present significant diagnostic problems when poorly differentiated. To identify a tumor as neuroendocrine, pathologists commonly use either immunocytochemistry or electron microscopy. In this report, the various immunocytochemical reagents are reviewed along with the ultrastructural features of neuroendocrine tumors. Site-specific variations in neuroendocrine tumors are discussed. A cost-effectiveness evaluation was performed on tumors from one laboratory which showed that electron microscopy was a less expensive diagnostic modality if more than three antibodies were necessary to arrive at the correct pathological diagnosis.     

Dermatofibrosarcoma Protuberans: Ultrastructural and Immunocytochemical Observations

In an attempt to elucidate the histogenesis of dermatofibrosarcoma protuberans, 38 specimens were examined by electron microscopy and immunocytochemistry. The cumulative evidence strongly favors a fibroblastic/myofibroblastic derivation.     

Myofibroblastoma of the Axilla

A mass in the axilla of a 47-year-old woman was biopsied and resected. The mass was composed of a loosely distributed population of spindle cells that were immunoreactive for smooth-muscle actin. Ultrastructurally, the cells possessed abundant endoplasmic reticulum, and some contained peripheral smooth muscle myofilaments, establishing that they were myofibroblasts. Mitotic activity was sparse, there was no cytologic atypia, and by flow cytometry the tumor was diploid with a low S phase. A diagnosis of myofibroblastoma was favored, although the possibility of a low-grade sarcoma could not be excluded. There has not been any indication of recurrence over a 4-month period of follow-up.     

Malignant Schwannomas Presenting as Malignant Fibrous Histiocytomas

Two soft tissue neoplasms considered to represent malignant fibrous histiocytomas by light microscopy showed typical findings indicative of Schwann cell origin when examined by electron microscopy. These findings included the presence of cells exhibiting long interdigitating cytoplasmic processes, which frequently contained collections of microtubules and were surrounded by thin, frequently interrupted, basal lamina material. In addition, pinocytotic activity at the cell surfaces and immature junctions joining apposing cellular membranes were identified. No evidence of fibroblastic, fibrohistiocytic, or myofibroblastic differentiation was identified ultrastructurally in the neoplastic cells.

Our findings stress the need for ultrastructural examination to adequately classify soft tissue sarcomas. The 2 cases presented illustrate that there are some schwannomas that may be inaccurately classified as malignant fibrous histiocytomas if only light mi-' croscopy is used. It seems that only by ultrastructural means is it possible to accurately classify these peculiar neoplasms.     

Malignant Myoepithelioma of the Larynx with Massive Metastatic Spread to the Liver: An Ultrastructural and Immunocytochemical Study

A malignant myoepithelioma arising in the submucosal glands of the larynx of a 71-year-old man is reported. The patient presented with a neck mass and massive metastatic involvement of the liver. Light microscopy of a liver biopsy specimen and fine-needle aspiration sample of the neck mass revealed a poorly differentiated carcinoma. Electron microscopic study of a second liver biopsy specimen demonstrated unequivocal features of myoepithelial differentiation; this was further confirmed by the strong cytokeratin and S-100 protein positivity and carcinoembryonic antigen negativity of the tumor cells. Myoepitheliomas are rare tumors, and most reported cases have been benign or of low-grade malignancy. The present case is unique because of its mode of presentation and fulminant course. It also underscores the usefulness of electron microscopy as a diagnostic modality in the work-up of metastatic lesions.     

Synaptic organization of the olfactory bulb based on chemical coding of neurons

Olfaction is one of the chemical senses in both vertebrate and invertebrate animals essential for a variety of social behaviors. Recent molecular biological and physiological studies using optical recording have indicated elaborate mechanisms in the main olfactory bulb for processing input from olfactory receptor neurons and control of output to higher centers in the brain. The current challenge is to identify a structural basis for understanding such elaborate molecular and functional organization. Immunocytochemistry and other advanced technologies have enabled us to label bulbar neurons selectively, and they have shown that the olfactory bulb has much greater heterogeneity in chemical and structural neuronal organization and in synaptic connectivity than previously believed. This review describes the structural aspects of the main olfactory bulb of rats and summarizes the findings for its synaptic organization based on chemical coding of neurons. Current uncertainties and issues that need to be clarified in the future are also discussed.     

So-Called Glandular Schwannoma: Ependymal Differentiation in a Case

A cervical root tumor in a patient with neurofibromatosis showed a biphasic pattern of spindle and epithelioid cells with prominent “gland” formation, characteristic of the so-called glandular schwannoma. Electron microscopy and histochemistry of the “glands” disclosed features consistent with an ependymal differentiation. It is noted that there is a curious preferential association of ependymal lesions and neurofibromatosis, the pathogenesis of which is not understood.     

Heterogeneity of Malignant Schwannomas

Six malignant schwannomas were studied by electron microscopy and immunohistochemistry for S-100 protein at the light and electron microscopic levels to clarify the nature of the tumor cells. Three tumors (group A) were composed of poorly differentiated tumor cells and showed no immunoreactivity for S-100 protein. One tumor (group B) was composed of perineurial cells that were S-100 protein-negative. Two tumors (group C) consisted of both Schwann cells and fibroblastic cells like neurofibromas, and only the former were found to contain S-100 protein. Thus, this study showed the heterogeneous nature of the malignant schwannomas and suggested that these tumors might arise from multipotential Schwann cells or different cellular components of peripheral nerve or primitive cells.