Biomedical subjects
J A Shaw
Publications and source records attributed to J A Shaw.
Cytomorphologic features of Merkel cell carcinoma in fine needle aspiration biopsies. A study of two atypical cases.
OBJECTIVE: To report atypical cytomorphologic features in fine needle aspiration biopsies (FNABs) from two cases of Merkel cell carcinoma (MCC), a primary neuroendocrine neoplasm of skin. STUDY DESIGN: Retrospective review of FNABs with histologic correlation from six patients with MCC and a report of findings from two whose smears showed atypical features. RESULTS: Typically the aspirates produce highly cellular smears of loosely clustered and individual, relatively monomorphic, small tumor cells with round to oval, regularly contoured nuclei. In two of our cases, the tumor cell nuclei exhibited a spectrum of pleomorphism ranging from moderately complex nuclear membranes with cleaves, indentations and protrusions in one case to large, markedly bizarre, convoluted nuclei and multinucleate tumor cells in the extreme case. Both cases were primary neoplasms, and the diagnosis was based on clinical, histologic and immunohistochemical data. Additionally, electron microscopy was performed on the tumor with bizarre nuclei and demonstrated rare, dense core neurosecretory granules and paranuclear bundles of intermediate filaments.
Sclerosing stromal tumor of the ovary: an ultrastructural and immunohistochemical analysis with histogenetic considerations.
Sclerosing stromal tumors are rare, benign ovarian neoplasms of unknown etiology and histogenesis. Three sclerosing stromal tumors were evaluated by immunohistochemistry and electron microscopy and were compared to two thecomas and nonneoplastic ovarian mesenchymal tissue. The sclerosing stromal tumors and thecomas were positive for muscle-specific actin; immunoreactivity was intense in the cellular areas of the sclerosing stromal tumors and focal in the thecomas. This antigen was expressed in nonneoplastic stroma predominantly in a perifollicular (theca externa) distribution. Two sclerosing stromal tumors and both thecomas were vimentin positive. Desmin was present in nonvascular cells in one of each tumor type. Expression of vimentin diffusely and of desmin focally was present in nonneoplastic cortical stroma and surrounding follicles. All specimens were nonreactive for cytokeratin. Electron microscopy supported differentiation toward smooth muscle in the sclerosing stromal tumors but not in the thecomas. Such differentiation included aggregates of cytoplasmic filaments with interspersed dense bodies, pinocytotic vesicles, and basal lamina. Delicate, long processes interconnected cells, often with primitive junctions, in the hypocellular foci. Cytoplasmic lipid, which was present in the thecomas, was not well developed in the sclerosing stromal tumors. It is proposed that a population of muscle-specific actin-positive elements exists in the theca externa--the perifollicular myoid stromal cell--and that sclerosing stromal tumors may originate from them. Sclerosing stromal tumors and thecomas share many antigenic determinants and morphologic features and thus are probably closely related entities.
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Posterior stabilization of pelvic fractures by use of threaded compression rods. Case reports and mechanical testing.
Threaded compression rods were placed between the posterior-superior spines as a means of posterior stabilization of pelvic fractures. To document the increase in sacroiliac stability afforded by this technique, biomechanical testing was performed. Malgaigne-type fractures with sacroiliac disruptions were created in four cadaver pelvises. The fractures were stabilized with anterior frames of the Slatis or Pittsburgh type and subjected to longitudinal and torsional loading patterns on an Instron machine. The anterior fixation was then augmented with threaded compression rods placed between the posterior-superior spines to compress the disrupted sacroiliac joints, and repeat testing was conducted. Anterior frames alone were found to provide little stabilization of the disrupted sacroiliac joints with either longitudinal or torsional loading. Markedly improved stabilization in both loading modes was achieved with posterior augmentation. Two typical cases are presented to demonstrate that posterior stabilization is as efficacious in clinical practice as in the biomechanics laboratory.