Biomedical subjects
D R Gnepp
Publications and source records attributed to D R Gnepp.
Central neurofibromas of the mandible: report of two cases.
Two cases of intramandibular neurofibromas unassociated with Von Recklinghausen's disease are presented and the literature is reviewed.
Sebaceous differentiation in adenoid cystic carcinoma of the parotid gland.
The first reported case of sebaceous differentiation in adenoid cystic carcinoma is presented. The tumor arose in the superficial lobe of the left parotid gland of a 48-year-old white man, had a predominantly solid histologic pattern, and manifested focal sebaceous differentiation in each of three recurrences over a two-year period. Review of the medical literature suggests that sebaceous differentiation is a normal property of some salivary ducts and may be found in any type of salivary gland neoplasm which has a ductal component. The differential diagnosis of sebaceous and clear cell lesions of salivary glands is discussed.
Benign lymphoepithelial parotid cyst with sebaceous differentiation--cystic sebaceous lymphadenoma.
A case of benign lymphoepithelial parotid cyst with sebaceous differentiation, or cystic sebaceous lymphadenoma, in a 57-year-old white man is presented. The literature on lymphoepithelial cysts and sebaceous lymphadenomas of the parotid gland is reviewed, and the alternative hypotheses of "branchial cleft origin" and "intranodal salivary gland inclusion origin" are compared. This case lends support to the intranodal glandular inclusion theory for lymphoepithelial cysts of the parotid.
Scanning electron microscopic study of canine lymphatic vessels and their valves.
The morphology of canine thoracic duct, peripheral collecting lymphatics and their valves was determined using scanning and transmission electron microscopy (SEM and TEM). Information from surface and subsurface structures was derived simultaneously in the SEM by using a heavy metal stain combined with backscattered electron imaging. The peripheral lymphatics and thoracic duct were covered by a continuous sheet of endotheial cells, the nuclei of which were slighly raised, avoid in shape with coarsely granular chromatin and long axes oriented parallel to the direction of flow. The immediate subendothelial connective tissue in the thoracic duct was primarily smooth muscle, whereas in the peripheral lymphatics reticular and elastic fibres predominated. Valves were seen in both peripheral and central lymphatics. These were covered with endothelium similar to the collecting lymphatic vessels, were usually bicuspid and had cusps that inserted either at a single point or overlapped prior to a wide based insertion. A complex network of connective tissue and elastic fibres was seen in valves and in the vessel walls adjacent to the valves. The similarities and dissimilarities of the SEM appearances of lymphatics arteries and veins are discussed.
Massive coronary arterial aneurysm.
The pathologic and echocardiographic findings of a massive right coronary arterial aneurysm in a 62 year old man are presented. The thrombosed aneurysm simulated a cardiac tumor, destroying one pulmonary valve cusp. It also caused marked pulmonary stenosis with elongation and narrowing of the outflow tract of the right ventricle and fixation of half of one cusp of the tricuspid valve.
Scanning electron microscopy of collecting lymphatic vessels and their comparison to arteries and veins.
The morphology of canine thoracic duct and peripheral collecting lymphatics was determined using light microscopy together with scanning and transmission electron microscopy (SEM and TEM). The thoracic duct was compared to the thoracic aorta and to the vena cava. Luminal surface detail was determined using the secondary imaging mode of the SEM. Subsurface nuclear and connective tissue detail was determined using back-scattered electron imagining combined with Willard's modification of Gomori's Methenamine Silver Stain. Central and peripheral lymphatic vessels have surface morphology distinct from either arteries or veins. The endothelial cell density in lymphatic vessels is less than in arteries or veins. The nuclear chromatin of lymphatic endothelial cells is coarsely granular and evenly distributed. This contrasts with nuclei from arteries or veins in which the chromatin is segmented. The distribution and orientation of lymphatic subsurface connective tissue fibers also differs from that seen in arteries and veins. It is concluded that canine lymphatic vessels have a unique surface and subsurface morphology and can be unequivocally identified by SEM.
Miliary pulmonary nodules due to aspirated vegetable particles.
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Primary mucinous carcinoma of the skin.
Only twenty-seven cases of primary mucinous carcinoma of the skin have been reported. Three additional cases are included in this paper. The clinical presentation is distinctive; they are found most commonly in middle-aged, black males in the head and neck region as painless nodules, usually less than 3 cm in diameter. Previous reports have indicated the probable sweat gland origin of these tumours; one of our cases demonstrates a transition from a solid hidradenoma-like pattern to nests of tumour cells floating in mucin lakes, adding support for the sweat gland hypothesis. The clinical behaviour is relatively benign; late recurrences are common but metastases are rare. Only one case had widespread metastases. Although the histological appearance is distinctive, other primary sites first must be excluded. Local excision is the treatment of choice.
Effects of lymphatic transport of enzyme on plasma creatine kinase time-activity curves after myocardial infarction in dogs.
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The effect of passive motion on the flow and formation of lymph.
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A silicone rubber that cures rapidly at body temperature.
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The bicuspid nature of the valves of the peripheral collecting lymphatic vessels of the dog.
A controversy presently exists about the structure of lymphatic valves, the bicuspid structure vs. the funnel-like architechture. This present study, along with a review of the literature was undertaken in an attempt to clarify this controversy. Twenty lymphatic valves from the collecting lymphatic channels draining the back paw region in four dogs were examined and several were photographed. The bicuspid nature and the three dimensional anatomy of these valves is clearly demonstrated.
Laryngeal precancer: a review of the literature, commentary, and comparison with oral leukoplakia.
Laryngeal keratosis (LK) is a precancerous mucosal change with great similarity to oral leukoplakia. Its malignant transformation rate varies from 1% to 40%, with the highest rates being found in patients microscopically diagnosed as "keratosis with atypia" (KWA). Recent evidence indicates that even cases with only mild or moderate epithelial dysplasias are at increased risk for malignant transformation, with the highest rates occurring in patients with more severe dysplasia or carcinoma in situ. Approximately 81% of LK patients are men and the average age at diagnosis is 50 years, a decade younger than that for laryngeal carcinoma patients. A high proportion of LK patients are tobacco smokers (84%) and alcohol abusers (at least 35%). LK is almost always found on the true vocal cords and is usually bilateral (67%). Clinical signs of high risk include, in decreasing order of importance: erythroplakia, surface granularity, increased keratin thickness, increased size, recurrence after conservative removal, and long duration. The annual incidence of LK in the United States is 10.2 and 2.1 lesions per 100,000 males and females, respectively.
Combined strategy of conventional cytogenetics, fluorescent in situ hybridization and chromosome morphometry for analysis of parotid gland tumor.
The limiting factors in conventional cytogenetic analysis of cell culture, especially of solid tumors, include insufficient metaphases, overgrowth of abnormal mitotic cells by normal cells, and suboptimal quality of harvesting and banding. Despite the availability of numerous protocols to induce G-banding, as well as Q-, R-, and C-banding, occasions still arise in which the analysis is severely limited by these factors and incomplete conclusions are often drawn as to the precise nature of the chromosomal abnormality, if indeed any can be detected. By adopting a rational approach of (1) close monitoring of cultures and rapid harvesting as soon as it is feasible, and (2) analysis of available metaphases by a combination of the GTG technique, fluorescent in situ hybridization (FISH), and chromosome morphometry using a graphic arts tool, a significant improvement in success rate may be more readily achieved. Here pathological and cytogenetic data are presented of a case of parotid gland carcinoma ex mixed tumor with the karyotype of 46, XX, del(5)(q12), dir ins(8;5)(q12;q12qter), add(12)(p13)/46, XX. This case is utilized to illustrate the importance of application of our combined strategy.