Enhanced procedural blank control for organic geochemical studies of critical sample material.

Organic contamination of sedimentary rocks can produce artefacts in studies of hydrocarbon composition, and this can have significant negative consequences for interpretations of the geobiological record. False positives - that is cases of non-syngenetic hydrocarbon biomarkers - are common in Precambrian studies, and significant challenges persist despite the intensive effort devoted to these studies. Efforts to standardize the 'burden of proof' for distinguishing between contamination and syngenetic material have to date failed to yield a simple or universal protocol, yet the need remains great, as both bitumen-lean rocks and bitumen-rich samples can be vulnerable to the accumulation of false-positive signals. In an effort to determine the best approach to quality control, we tested the capability of different blank materials to collect ambient contamination by assessing their capacity to adsorb hydrocarbons during storage in plastic bags and found that commonly used Quartz sand does not provide an adequate measure of storage- or laboratory-induced contamination. Brick blanks, having the advantage that they can parallel rock samples even during the sawing process, are characterized by similar poor adsorption properties. Primarily steered by mineralogy, organic carbon content and surface area, model-black shales can adsorb up to 20 times more contaminants than sand blanks and up to 200 times more contaminants than organic-free model-carbonates. This observation provides an explanation for reports and observations of seemingly systematic stratigraphic variation of contaminants, but mostly should raise awareness for the evaluation of procedural blanks, in particular of sample-to-blank ratios, when studying bitumen-lean rock samples of varying lithologies. Additionally, differences between the hydrocarbon profiles in plastic bags and the hydrocarbon signatures transferred to blank materials emphasize difficulties in the unequivocal detection of contamination sources. Artificial black shale pellets can provide enhanced contamination control in biomarker studies - particularly for exceptionally vulnerable samples such as Precambrian rocks, meteorites or extraterrestrial sample-return material.

Oral mucosal melanomas: the WESTOP Banff workshop proceedings. Western Society of Teachers of Oral Pathology.

A workshop to discuss primary oral melanomas was convened at the annual Western Society of Teachers of Oral Pathology meeting in Bannf, Alberta, Canada. Fifty oral melanomas, identified from the files of the participants, were reviewed in order to better understand the clinical features, histologic spectrum, and natural history of these perplexing lesions. Results confirmed that oral melanomas occur in adults almost three times more frequently in men than women and have a decided predilection for the palate and gingiva. Some lesions exhibit a clinically detectable and prolonged in situ growth phase, whereas others seem to lack this property and exhibit only or predominantly invasive characteristics. Recurrences, metastases, and death from tumor were characteristic of the follow-up of a limited number of patients. Until definitive prospective data are collected that elucidate natural history, oral mucosal melanomas should be tracked separately from cutaneous lesions. All oral pigmented lesions that are not clinically diagnostic should be biopsied. Lesions with equivocal histopathologic features might be referred to as "atypical melanocytic proliferation" and should be excised. Recognition of lesions in an early in situ phase and aggressive treatment should have a favorable effect on prognosis. To enhance future or prospective study of these rare neoplasms, guidelines for reporting oral melanomas are suggested.

Reactivity of monoclonal antibodies 17.13 and 63.12 with oral epithelial dysplasia and hyperkeratosis.

Monoclonal antibodies (MAbs) 17.13 and 63.12 exhibit characteristic reactivity patterns in normal stratified squamous epithelium, as well as highly sensitive and specific altered reactivity patterns in squamous cell carcinoma. The purpose of this study was to critically evaluate the patterns of reactivity of MAbs 17.13 and 63.12 in 43 biopsies of clinical oral leukoplakia or erythroleukoplakia with microscopic diagnoses of hyperkeratosis or epithelial dysplasia. Altered carcinoma-like reactivity patterns were seen in 72% of hyperkeratoses and in all cases of epithelial dysplasia, but varied in the level of epithelial strata exhibiting altered reactivity. Increased frequency of altered reactivity within the epithelial strata was associated with the presence, but not the grade of, epithelial dysplasia, as well as with the presence, intensity; and pattern of submucosal inflammation. The results of this study suggest that altered reactivity patterns of MAb 17.13 are associated with epithelial dysplasia and may be of assistance in detecting precancerous changes in hyperkeratoses before morphologically identifiable epithelial dysplasia. The association of submucosal inflammation with altered MAbs 17.13 and 63.12 reactivity may indicate either a decrease in specificity of these antibodies for precancerous change or an increased significance of inflammation in precancerous lesions.

Pigmented lateral periodontal cyst and other pigmented odontogenic lesions.

OBJECTIVE: To report a case of lateral periodontal cyst (LPC) with marked melanin pigmentation in a 38-year-old Black male and to discuss the phenomenon of melanin pigmentation in odontogenic cysts and tumors. RESULTS: Histologically, the epithelial lining of the LPC contained an abundant amount of melanin granules throughout the entire epithelium. Ultrastructurally, epithelial cells contained mature melanosomes (stage IV melanosomes). Melanophages containing aggregates of melanosomes were identified in the connective tissue cyst wall. Perusal of the literature revealed that melanin pigmentation in odontogenic lesions is uncommon. Melanin has been reported in calcifying odontogenic cyst (18 cases), odontogenic keratocyst (8 cases), adenomatoid odontogenic tumor (3 cases), ameloblastic fibroma (3 cases), odontoma (2 cases), and ameloblastic fibro-odontoma, odonto-ameloblastoma, and odontogenic fibroma (1 case each). CONCLUSIONS: Almost all pigmented odontogenic lesions; occurred in Blacks and Asians; they are almost non-existent in Whites. Thus, racial pigmentation probably plays an important role in such lesions.

Peripheral (extraosseous) calcifying odontogenic cyst. A review of forty-five cases.

The peripheral calcifying odontogenic cyst (PCOC) is a rare lesion. The number of well-documented cases reported in the English-language literature until now is 38. The purpose of the present study is twofold: (1) to report seven new cases of PCOC and (2) to review and analyze the clinical and histomorphologic features of the previously reported cases of PCOC together with those of the present study. Most of the lesions were located in the maxillary and mandibular gingiva or alveolar mucosa anterior to the region of the first molar. Histologically, 66% of the lesions were of the cystic variant and 34% of the solid (neoplastic) variant. The terminology of the lesion and its histogenesis are discussed.

Adenomatoid hyperplasia of minor salivary glands.

Adenomatoid hyperplasia of minor salivary glands is an uncommon clinicopathologic entity. It comprises clinical swelling resembling a neoplasm with a histologic picture of aggregates of normal-appearing salivary gland tissue in excess of that anticipated for the anatomic site. The significance of this lesion is derived from its clinical resemblance to a neoplasm of salivary gland origin. This study adds 40 new cases to the literature and analyzes their clinical and histologic features. Most of the lesions were located on the hard and soft palates. The exact nature of the minor salivary gland hyperplasia is not clear. Some of the cases may represent a hamartoma or a reactive hyperplasia, but in most cases the nature of the hyperplasia is idiopathic.

Anterior lingual mandibular salivary gland defect. Evaluation of twenty-four cases.

Lingual mandibular salivary gland defects in the posterior part of the mandible are not uncommon. Analogous defects in the anterior region, however, are rare, and the four new cases presented in this report bring the total number of reported cases up to 24. The purpose of the present study was to review and analyze the clinical, radiographic, and histologic features of the previously reported cases together with those of the present study. The majority of these defects were located in the cuspid and/or premolar area and were diagnosed in men in their fifth and sixth decades of life. Almost all defects contained normal salivary gland tissue. The differential diagnosis, treatment, and pathogenesis of these defects are discussed.

Melanocytic hyperplasia of the oral mucosa.

Lesions that exhibit melanocytic hyperplasia are uncommon in the oral mucosa. They are even more rare than the various morphologic types of nevomelanocytic lesions. This article reports the clinicopathologic features of oral lesions diagnosed as lentigo simplex, junctional lentigo ("jentigo"), atypical melanocytic hyperplasia (melanoma in situ), and melanocanthoma. The proper terminology for these lesions is also discussed.

Histologic evaluation of the bone/graft interface after mandibular augmentation with hydroxylapatite/purified fibrillar collagen composite implants.

Samples of the bone/graft interface were evaluated histologically in five patients 1 year after mandibular ridge augmentation with a composite of hydroxylapatite particles in a matrix of purified fibrillar collagen (HA/PFC). The resulting defects were refilled with HA/PFC after the biopsy specimens were obtained. Histologic examination of the specimens yielded no evidence of purified fibrillar collagen. Hydroxylapatite particles were surrounded by dense fibrous host connective tissue, trabeculae of woven and lamellar bone, or both. HA/PFC was found to be biocompatible with human tissue and receptive to direct bone apposition on the hydroxylapatite particles.

Oral focal mucinosis.

Oral focal mucinosis (OFM) is an uncommon clinicopathological entity which is considered to be the oral counterpart of cutaneous focal mucinosis and/or cutaneous myxoid cyst. It is comprised of a clinically elevated mass with a histological picture of localized areas of myxomatous connective tissue. The present study adds 15 new cases of OFM to the literature and analyzes their clinical, histological and histochemical features. Most of the lesions were located in the gingiva and alveolar mucosa. The nature of the lesion is unclear and it is suggested that the mucinous accumulation is the result of fibroblastic overproduction of hyaluronic acid.

Central (intraosseous) calcifying odontogenic cyst.

The central calcifying odontogenic cyst (CCOC) is an uncommon lesion. The present study reports 17 new cases of CCOC and analyses their clinical and histomorphologic features. The data revealed that CCOC were usually diagnosed in the second decade of life with an almost equal distribution between the maxilla and the mandible. Six of the 17 cases (35%) were associated with odontomas and 6 lesions (35%) were associated with unerupted teeth. Histologically, most of the lesions were unilocular cysts but at least one was multilocular and one was a mixed lesion - partially cystic and partially solid. Excision with long-term follow-up (up to 10 years) is the treatment of choice.

Oral intravascular papillary endothelial hyperplasia.

Intravascular papillary endothelial hyperplasia (IPEH) is usually a cutaneous lesion thought to represent a peculiar manifestation of an organizing thrombus. IPEH can be subdivided into a pure form that occurs within a dilated vascular space and a mixed form that appears as a focal change within a preexisting vascular lesion, such as hemangioma. The principle significance of the lesion lies in the fact that it may be mistaken for angiosarcoma. Oral lesions are uncommon and the present paper reports on 16 new cases of oral IPEH, analyzing their clinical and histomorphologic features. Histologically, 11 lesions appeared in a pure form and 5 lesions in a mixed form. Thrombi were detected in all but one case. The most common location was the lip, followed in decreasing frequency by the tongue and buccal mucosa. Local excision was the treatment of choice.

The retrocuspid papilla of the mandibular lingual gingiva.

The retrocuspid papilla (RCP) is a circumscribed nodule that lies lingual to the mandibular cuspid on the gingival tissue. RCP is observed more frequently in young children and seems to regress or disappear with age. Little information is available in the literature on this entity and there are contradictory reports regarding its histologic features. Histomorphologic analysis of 30 specimens diagnosed as RCP revealed that in most cases (80%) it is composed of loosely-arranged delicate fibrous connective tissue with stellate and multinucleated fibroblasts. Elongation of the rete ridges and/or increased vascularity are also present in a significant number of cases. Stellate and multinucleated fibroblasts are not unique to RCP and they have been described as prominent histologic features in other lesions of skin and mucous membrane. RCP is considered to be a "normal anatomical structure" or an "anatomic variation" of the gingiva. The clinical significance of RCP is that it may simulate pathological gingival conditions from which it must be differentiated.

Melanocytic nevi of the oral mucosa: a clinicopathologic study of 130 cases from northern California.

This paper presents analysis of data on 130 cases of oral melanocytic nevi from the files of the University of the Pacific, San Francisco and the University of California, San Francisco. This is the largest detailed series from one geographic location published to date. Nevi of the intramucosal type are the most common (63%) followed by the common blue nevus (19%). Compound nevi are uncommon (9%) and junctional nevi are rare (5%). Combined nevi are the rarest type (4%). The data are analyzed as to the location, presence of clinical pigmentation, configuration, and size of the nevi, as well as the patient's age, gender and race. Because the malignant potential of oral nevi is still uncertain and because preexisting macular pigmentation is present in about one third of all patients with oral melanoma, it is advisable to remove all pigmented lesions suspected to be melanocytic nevi.

Multicentric familial squamous odontogenic tumor.

Three cases of multicentric squamous odontogenic tumor, one of which was previously reported, are presented in three black siblings. A review of the literature indicates that 5 of the 26 previously recorded cases arose in multiple sites, but no evidence of familial history has been suggested. Although squamous odontogenic tumor has been described as a relatively rare, benign odontogenic neoplasm, the multicentric familial nature of our present cases suggests this represents either a reactive hyperplasia or hamartoma of residual odontogenic epithelium within the periodontal tissues. Management of previous cases has varied from simple curettage to maxillectomy with only one case of recurrence.

Oral granular cell tumors: a clinicopathologic and immunocytochemical study.

To investigate the histogenesis of the granular cell, a large series of granular cell tumors was studied for clinical and histopathologic features with emphasis on immunocytochemical markers. The nongingival granular cell tumors (NGGCT) were found to be more prevalent among females than males by a ratio of 2:1 and arose on the tongue (67%), the buccal mucosa (13%), the lips (8%), the soft palate (6%), and other sites (6%). With the use of the avidin-biotin-peroxidase method, polyclonal rabbit antisera were employed. The antisera were directed to the following antigens: S-100 protein, myoglobin, myosin, actin, desmin, alpha-1-antitrypsin, and muramidase. Results indicated that granular cell tumors are not homogenous for immunocytochemical markers. Nongingival granular cell tumors were universally positive for S-100 protein and failed to exhibit immunoreactivity for myogenous or histiocytic markers. Alternatively, the gingival granular cell tumor of infancy was negative for all markers, whereas rhabdomyoma was reactive with myogenous markers and a subpopulation of tumor cells displayed S-100 protein immunoreactivity. The granular cell ameloblastoma was reactive only with antiserum to alpha-1-antitrypsin. Ultrastructurally, granular cells from one of two NGGCT showed a direct evolution from skeletal muscle fibers. It is concluded that the oral NGGCT is a tumor positive for S-100 protein that may arise from muscle or nerve sheath.

Generalized hypercementosis.

The case of an elderly female patient with a long-standing history of generalized hypercementosis is described. A thorough review of the literature indicates that this may be one of the most extensive cases of hypercementosis to be reported. Possible etiologic factors--including heredity, systemic disorders, chronic periapical infection, and abnormal occlusal trauma--are discussed.