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Biomedical subjects

B Mackay

Publications and source records attributed to B Mackay.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Electron microscopy in the diagnosis of small round cell tumors of bone.

Small round cell tumors involving bone can present problems in differential diagnosis by light microscopy. In exploring the role of electron microscopy in this situation, seven small cell osteosarcomas and seven mesenchymal chondrosarcomas were examined by electron microscopy and compared with typical and atypical Ewing's sarcomas. There is much overlap in the ultrastructural features of these tumors, but electron microscopy is helpful to establish or confirm a diagnosis of typical Ewing's sarcoma and, if representative matrix is present, of small cell osteosarcoma.

Bone Neoplasms↗
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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.

Axilla↗
PubMedDate not supplied

Myoepithelioma of the retroperitoneum.

An abdominal mass detected in a 36-year-old man was thought from radiologic studies to be a renal neoplasm, but at surgery the kidney was found to be uninvolved. The 9.5-cm retroperitoneal tumor was resected totally and found to be encapsulated, and it appeared to be benign by light microscopy. The pattern of the spindle cells throughout the tumor suggested a cellular schwannoma, but immunocytochemical and ultrastructural studies did not support schwannian differentiation and instead revealed epithelial and smooth muscle features compatible with a myoepithelioma.

Actins↗
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Primary intraoral epithelioid hemangioendothelioma presenting in childhood: review of the literature and case report.

Epithelioid hemangioendothelioma (EH) is a recently described vascular neoplasm of borderline or intermediate malignant potential. This tumor arises from medium- to large-sized vessels, primarily involves the soft tissues of the extremities as well as the liver and lung, and rarely occurs in the head and neck region. Only eight well-documented cases of intraoral EH have been reported. We present an additional pediatric case of EH confined to the oral cavity and review the literature regarding EH presenting as an intraoral mass. EH is characterized histopathologically as an epithelioid lesion arranged in nests, strands, and trabecular patterns with infrequent vascular spaces. Occasional erythrocytes within intracytoplasmic lumina may be seen in tumor cells. Ultrastructural examination typically shows intracytoplasmic lumina with pseudopodial cellular membrane extensions. The cytoplasm usually contains intermediate filaments infrequently associated with Weibel-Palade bodies. Neoplastic cells are immunoreactive for factor VIIIR:Ag and Ulex europaeus. Histopathologic features, which may be associated with aggressive clinical behavior, include significant cellular atypia, one or more mitoses per 10 high-power fields, an increased proportion of spindled cells, focal necrosis, and metaplastic bone formation. Because of the intermediate malignant potential of epithelioid hemangioendothelioma, complete tumor resection is recommended for intraoral lesions.

Child↗
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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.

Aged↗
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Comparison of ultrastructural features among neuroblastic tumors: maturation from neuroblastoma to ganglioneuroma.

Neuroblastic tumors have the unique ability to differentiate and mature. This family of tumors is composed of the neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. These tumors are derived from primordial neural crest cells that form the sympathetic nervous system. The purpose of this study was to characterize the ultrastructural features of neuroblastic tumors in a pediatric population. Forty-five neuroblastic tumors (15 neuroblastomas, 15 ganglioneuroblastomas, and 15 ganglioneuromas) were examined using standard transmission electron microscopic techniques. Undifferentiated neuroblastomas were composed of primitive cells with rare neurite-like processes containing clear secretory vesicles and no Schwann cell differentiation. Poorly differentiated and differentiating neuroblastomas showed more frequent neuritic processes with infrequent dense core granules and infrequent immature Schwann-like cells. Ganglioneuroblastomas possessed an admixture of cell types, including immature ganglion cells without associated satellite cells, intermediate cells, and differentiating neuroblasts. The neuropil contained immature Schwann cells encasing haphazardly arranged neuritic processes. Ganglioneuromas were composed of mature ganglion cells with occasional binucleation. The neuropil contained mature Schwann cells with well-organized neuritic processes and abundant collagen deposition. Differentiation or maturation of tumor cells, neuritic processes, and Schwann cells may thus be discerned ultrastructurally in primary neuroblastic tumors in pediatric patients.

Cell Differentiation↗
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Clear cell mesothelioma.

A clear cell form of epithelial mesothelioma is described. This variant does not appear to have been previously described, and it merits recognition since it is readily confused by routine light microscopy with other tumors that involve the pleura, including metastatic carcinomas composed predominantly of cells with optically clear cytoplasm. Ultrastructural and immunohistochemical studies were helpful in reaching the diagnosis in this case, and electron microscopy is particularly recommended to investigate the differential diagnosis of unusual pleural tumors.

Aged↗
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Cellular schwannoma of the bronchus.

A cellular schwannoma in a bronchus of a 64-year-old female is reported with immunocytochemical and ultrastructural observations. One previous case arising in the lung has been reported. The tumor formed a 3-cm exophytic mass in a segmental bronchus. Pneumonectomy was performed. The tumor was moderately cellular and devoid of Verocay bodies, and the spindle cells were immunoreactive for S-100 protein. Electron microscopy revealed schwannian features that were less developed than in a classic schwannoma.

Bronchial Neoplasms↗
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Olfactory neuroblastoma: a case report.

A neuroblastoma arising in the nasal cavity of a 66-year-old male invaded the frontal sinus and extended into the cranial cavity. Light microscopy revealed sheets of small ovoid cells and many small glands bordered by columnar cells which were strongly immunoreactive to epithelial markers. Focal reactivity for synaptophysin and chromogranin was seen within the sheets of small cells. Electron microscopy confirmed the presence of olfactory differentiation.

Aged↗
PubMedDate not supplied

Clear-cell carcinoma: an ultrastructural study of 57 tumors from various sites.

Clear-cell carcinoma is a convenient and frequently used descriptive term for a malignant epithelial neoplasm that is entirely or largely composed of cells with optically clear cytoplasm in hematoxylin-eosin-stained sections. Transmission electron microscopy was performed on 57 tumors from various sites to investigate the fine structural basis for the clarity of the cytoplasm. The clear appearance resulted from the presence of one or several of the following features, as the sole or predominant cause or in combination: glycogen, lipid droplets, mucin vacuoles or diffuse mucosubstances, dilated cisternae, swollen or unusually large mitochondria, large solitary membrane-limited vacuoles or numerous smaller vacuoles, intracytoplasmic lumens, expanded intercellular spaces, cytoplasmic pseudoinclusions, and a paucity of organelles. Degenerative changes contributed to the clear appearance by inducing swelling of mitochondria and creating lucent cytosol. The factors responsible for the clear cytoplasm were not always consistent with regard to tumor type or site of origin, but glycogen was the commonest reason among the 57 tumors studied and the principal cause in tumors of the female genital tract, skin, and salivary glands, while renal cell carcinomas tended to possess an admixture of glycogen and lipid droplets. Because of the heterogeneity of the subcellular changes that can produce optically clear cytoplasm, electron microscopy has a limited role in determining the primary site of a metastatic clear-cell carcinoma.

Adenocarcinoma, Clear Cell↗
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Renal cell carcinoma with unusual differentiation.

A 4-cm tumor in the kidney of a 67-year-old male was focally a classical renal cell carcinoma with a papillary architecture and clear cells, but most of the tumor had an unusual pattern composed of paired sheets of cuboidal to flattened cells reminiscent of the loop of Henle.

Aged↗
PubMedDate not supplied

Endocrine carcinoma of the kidney.

A 4-cm mass in the right kidney of a 43-year-old female had an endocrine appearance by light microscopy and electron microscopy confirmed this impression, demonstrating the presence of numerous cytoplasmic granules of endocrine caliber. Unusual features were patchy immunoreactivity for chromogranin, and polarity of the granules within the neoplastic cells. Extrarenal extension and liver metastasis were documented.

Adult↗
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Solid and papillary tumor of the pancreas: ultrastructural observations on two contrasting cases.

Two papillary and solid tumors of the pancreas are reported which differed in their clinical features, ultrastructure, and biologic behavior. Both tumors contained papillary and solid areas by light microscopy. One tumor followed the more usual indolent course. The second patient presented with a liver metastasis and died of progressive disease in a relatively short period of time. Neither neoplasm showed convincing immunohistochemical or ultrastructural evidence of endocrine differentiation, but the electron microscopic findings hinted that this tumor possesses at least latent endocrine properties.

Adult↗
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Small cell undifferentiated carcinoma of the pancreas.

Small cell undifferentiated carcinoma of the pancreas is a rare neoplasm: Only 12 cases have previously been documented. This paper describes the clinical evolution, immunohistochemical profile, and ultrastructural features of a case occurring in a 37-year-old woman.

Adult↗
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Epithelioid hemangioendothelioma of soft tissue: report of a case with ultrastructural observations.

The ultrastructure of an epithelioid hemangioendothelioma arising in the soft tissues of the neck of an 18-year-old female is reported. Comparison with similar tumors in other sites from the authors' electron microscopy files indicates that diffuse nonspecific intermediate filaments, pinocytotic vesicles, intracytoplasmic lumens, and pericytic cells are frequent but variable features of this neoplasm.

Adolescent↗
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Alveolar soft-part sarcoma: a review of the pathology and histogenesis.

The descriptive designation, alveolar soft-part sarcoma, continues to be used for this uncommon soft-tissue malignancy because an acceptable hypothesis for its histogenesis has not been advanced, despite studies with electron microscopy and immunohistochemistry. These techniques have, nevertheless, provided significant information that is useful in the differential diagnosis of the tumor and pertinent in speculation concerning its nature. The most intriguing ultrastructural feature is the secretory process that culminates in the formation of the distinctive cytoplasmic crystals. Myogenic differentiation has been favored in a number of recent reports on the basis of immunohistochemical findings and the presence of the crystals does not rule out the possibility, but accounts of immunoreactivity for the myogenic regulatory protein MyoD1 have not been confirmed in subsequent studies or in the authors' own staining of six cases.

Adolescent↗
PubMedDate not supplied

Landmark discrimination learning in the dog.

Allocentric spatial memory was studied in dogs of varying ages and sources using a landmark discrimination task. The primary goal of this study was to develop a protocol to test landmark discrimination learning in the dog. Using a modified version of a landmark test developed for use in monkeys, we successfully trained dogs to make a spatial discrimination on the basis of the position of a visual landmark relative to two identical discriminanda. Task performance decreased, however, as the distance between the landmark and the "discriminandum" was increased. A subgroup of these dogs was also tested on a delayed nonmatching to position spatial memory task (DNMP), which relies on egocentric spatial cues. These findings suggest that dogs can acquire both allocentric and egocentric spatial tasks. These data provide a useful tool for evaluating the ability of canines to use allocentric cues in spatial learning.

Animals↗