Biomedical subjects

K Hewan-Lowe

Publications and source records attributed to K Hewan-Lowe.

9 recordsLinked to original sources

PubMed1992

Merkel cell carcinoma of the labial mucosa. An immunohistochemical and ultrastructural study with a review of the literature on oral Merkel cell carcinomas.

Merkel cell carcinoma is a rare cutaneous neuroendocrine tumor that occurs predominantly in the head and neck region of older patients. An 88-year-old white man had an erythematous, umbilicated tumor on his lower lip, which on histopathologic examination showed solid sheets of infiltrating basaloid round cells with a high mitotic index. Globular, paranuclear immunostaining for low-molecular-weight cytokeratins (Nos. 8, 18, and 19) and neurofilament was observed. On ultrastructural examination, the tumor cells demonstrated paranuclear whorls of intermediate filament aggregates and occasional electron-dense granules. This unique cytokeratin- and neurofilament-staining pattern with coexpression enabled the Merkel cell carcinoma to be differentiated from other small cell malignant tumors that included metastatic neuroendocrine carcinomas from other regions. The follow-up 1 year after surgery and radiation showed that the patient remained disease free. Review of the literature revealed 11 cases of oral Merkel cell carcinomas with a predilection for the labial mucosa of older men. The mode of treatment and the clinical course of these cases are also presented, with an update on therapeutic management of Merkel cell carcinomas.

Aged↗

PubMed1991

Association of human papillomavirus with penile carcinoma: a study using polymerase chain reaction and in situ hybridization.

Although carcinoma of the uterine cervix has been shown to be strongly associated with human papillomavirus (HPV) infection, a sexually transmitted disease, similar detailed data are lacking in penile carcinoma. To determine the association of HPV with penile carcinoma, we examined 30 specimens of penile carcinoma from 23 patients by the highly sensitive polymerase chain reaction (PCR) and in situ hybridization assays. We also examined nonneoplastic penile foreskins from 20 adults using the polymerase chain reaction assay. Human papillomavirus type 16 genome was found in 15 patients (65%), HPV type 30 was found in three (13%), and HPV type 6/11 was found in two (9%). These HPV types were not detected in any of the nonneoplastic foreskins. As in cervical carcinoma, HPV, particularly type 16, is strongly associated with penile carcinoma and may play an etiologic role in the development of this neoplasm.

Base Sequence↗

PubMed1991

Glassy cell features in adenosquamous carcinoma of the uterine cervix. Histologic, ultrastructural, immunohistochemical, and clinical findings.

Glassy cell features (GCF) were identified as composing a predominant pattern (more than 85% of histology) in six cases and a focal pattern (33-85% of histology) in 10 cases of a series of 53 adenocarcinomas (AC) and adenosquamous carcinomas (ADSQ) of the uterine cervix. In three cases examined ultrastructurally, GCFs correlated with many cytoplasmic polyribosomes and abundant rough endoplasmic reticulum, but Golgi complexes and tonofilaments were scant and intracytoplasmic lumina were absent. Intracellular mucin was present in the areas showing GCFs of four ADSQs with predominant GCFs and six ADSQs with focal GCFs. Two of three cases examined ultrastructurally showed intracellular electron-dense material that corresponded to mucin secretory material. Immunohistochemical studies of the six ADSQs with predominant GCF cases showed the following pattern of reactivity: monoclonal carcinoembryonic antigen (CEA), 2 of 6 cases; polyclonal CEA, 3 of 6; CA 125, 0 of 6; CA 19-9, 0 of 6; placental alkaline phosphatase, 0 of 6; and vimentin, 1 of 6. Focal GCF areas showed monoclonal CEA, 4 of 9 cases; polyclonal CEA, 3 of 9; vimentin, 4 of 9; while CA 125, CA 19-9, and placental alkaline phosphatase were negative in areas of GCFs. One of three patients with ADSQ with predominant GCFs and five of nine patients with ADSQ with focal GCFs with at least 1 year of follow-up were disease free. No association between GCFs (combined focal and predominant) and recurrent disease was present when compared to the other 29 AC and ADSQ patients with follow-up. Recurrent disease in our series of AC and ADSQ was only associated with stage III or IV disease at presentation (P less than 0.001). There was no association with adenosquamous histology, histologic grade, lymphatic invasion, or age. There were insufficient cases of ADSQ with predominant GCFs with follow-up to evaluate fully prognostic significance of this subgroup. Our study suggests that GCFs are part of the spectrum of differentiation in ADSQ of the cervix rather than a distinct histologic type of carcinoma with unique clinical significance.

Adenocarcinoma↗

PubMed1991

In situ oncocytic change in association with multiple renal cell adenocarcinomas.

We report a case of in situ oncocytic change in association with two low-grade renal cell adenocarcinomas and one contralateral low-grade oncocytic adenocarcinoma. The in situ oncocytic change showed abundant cytoplasmic mitochondria confirmed by ultrastructural examination and phosphotungstic acid-hemotoxylin staining. In addition, this in situ oncocytic change expressed cytokeratin CAM 5.2 in the absence of cytokeratin AE1/AE3, as reported in oncocytic renal cell adenocarcinomas. Further study of in situ oncocytic change identified in kidneys resected for adenocarcinomas with regard to follow-up and management of the contralateral kidney seems indicated.

Carcinoma↗

PubMed1990

Primary pulmonary alpha-fetoprotein-producing malignant germ cell tumor.

We are reporting the clinical and pathologic features of a primary, pulmonary, malignant germ cell tumor associated with a marked elevation of serum alpha-fetoprotein (38,427 ng/mL) and lactate dehydrogenase activity (756 U/L), in a 26-year-old female. This controversial, rare neoplasm has not been extensively discussed in the pathology literature. We emphasize the clinical importance of establishing this diagnosis in view of the favorable response to chemotherapy shown by malignant germ cell tumors.

Adult↗

PubMed1979

Predictive values of thyroxine, thyrotropin, and triiodothyronine concentrations in serum.

The predictive values of total thyroxine, thyrotropin, and total triiodothyronine concentrations in serum for clinically apparent and subclinical hypothyroidism and hyperthyroidism were determined by retrospective analysis of clinical cases chosen from the frequency distributions of hormone test results. Very low total thyroxine concentrations, less than 25 microgram/L, were specific for hypothyroidism. Most subclinical hypothyroid cases had intermediate or low total thyroxine concentrations, 35-60 microgram/L, with moderately increased thyrotropin concentrations, greater than 12 milli-int. units/L. Thyrotropin cut-off concentrations were identified that had predictive values greater than 90% for classifying untreated and hormone-treated hypothyroid cases. Above-normal total thyroxine concentrations, regardless of absolute value, were not specific for hyperthyroidism, because binding-protein alterations related to estrogen taking were prevalent and produced occasional marked increases in serum total thyroxine. Nevertheless, cut-off concentrations for serum total thyroxine and total triiodothyronine were identified that had a predictive value greater than 90% for hyperthyroidism, without necessitating measurement of the capacities or concentrations of hormone-binding proteins.

Adolescent↗

PubMedDate not supplied

Ovarian myxoma: ultrastructural and immunohistochemical findings.

The ultrastructural and immunohistochemical findings are reported in two ovarian myxomas, one of which was also associated with a sclerosing stromal tumor of the same ovary. Both neoplasms showed a myxoid, moderately cellular proliferation of spindle and stellate cells interspersed with areas of fibrosis and hemorrhage as well as delicate vascular spaces. Ultrastructurally, stellate neoplastic cells with irregular nuclei and occasional nucleoli were embedded in a mucinous and loose collagen matrix. Their cytoplasm showed abundant intracytoplasmic thin filaments that rarely condensed into poorly formed dense bodies. These thin filaments correlated with immunoreactivity for muscle-specific actin and vimentin. The neoplastic cells showed no immunoreactivity with antibodies to desmin, S-100 protein, cytokeratin AE1:AE3, factor VIII-related protein, or placental alkaline phosphatase. These ultrastructural and immunohistochemical findings are consistent with myofibroblastic differentiation. These ancillary studies exclude important, clinically more aggressive differential considerations such as myxoid rhabdomyosarcoma, myxoid liposarcoma, myxoid neural tumors, mucinous adenocarcinoma showing pseudomyxomatous change, and myxoid-appearing endodermal sinus (yolk sac) tumor.

Actin Cytoskeleton↗

PubMedDate not supplied

Microcomputer application: an image database system for electron microscopy.

An electron microscopist in a small electron microscopy laboratory that processes 200 cases per year can generate at least 2000 electron micrographs within this time period. These electron micrographs are stored in filing cabinets, which slowly encroach on existing laboratory space. Related image data are often located in separate filing systems. This type of storage system is inefficient for rapid retrieval of sets of electron micrographs for research, teaching, or retrospective review of patient material. An electron microscopy image base, which is implemented on a microcomputer, can provide flexible and simultaneous access to both digitized electron micrographs and their relevant textual data. In addition to the advantage of more efficient retrieval, electronic storage of textual data and digitized electron micrographs also offers the advantage of decreased storage space for this type of data. Implementation of the initial version of the electron microscopy image base demonstrated that future versions must provide improved resolution of the digitized electron micrograph and sufficient electronic mass storage to support such a large image base. Ongoing developments in database technology and mass storage make it worthwhile to pursue additional refinements of the electron microscopy image base.

Database Management Systems↗

PubMedDate not supplied

Diagnostic electron microscopy: future development.

When the electron microscope was initially developed, pathologists thought that it would become the ultimate diagnostic tool for tumor diagnosis because the structure of subcellular organelles could be visualized. However, the role of diagnostic electron microscopy in tumor diagnosis diminished rapidly when it was noted that there were a finite number of diagnostic subcellular organelles and that immunohistochemistry could yield the answer to questions which related to tumor diagnosis more rapidly and cheaply. If diagnostic EM is to remain a viable entity, its future role in tumor diagnosis lies in exploiting the relevance of the correlation between structure and function of subcellular organelles. This correlation between structure and function of subcellular organelles is best accomplished in an environment in which the recent technologic advances in electronics are incorporated into the electron microscopy laboratory.

Clinical Laboratory Techniques↗