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Notes: Abstract Cases of primordial cysts derived from the records of all the hospital pathology departments and private pathology practices on the Witwatersrand, were recorded for the 10-year period 1965-74. The population at risk (1970 census) was 974,390 Whites and 1,567,280 Blacks. Age-specific morbidity rates for each sex and race were calculated, as well as age-standardized incidence rates standardized against African, World and European standard populations. The age-standardized incidence rates for primordial cysts, standardized against a World standard population, per million per year are 0.61, 0, 4.86 and 3.50 for Black males and females and White males and females, respectively. In the population at risk, primordial cysts are much more common in Whites than in Blacks, the incidence being eight times higher in White males than in Black males. The present study confirms that there is a bimodal age distribution but with a higher incidence of the cyst in the age group 50–64 years than previously suspected. This may be either because a substantial number of cases remain undiagnosed for many years or because there are two groups of primordial cyst: one which is triggered in young patients and the other in older patients.

Notes: Abstract. Basal cell extensions have frequently been observed in a variety of odontogenic lesions as well as in the fibrous epulis (fibrous hyperplasia of the gingiva). In order to determine the frequency of these extensions in normal human oral mucosa, a study using autopsy and surgical material was conducted. The results indicated that a specific type of rete ridge morphology exists for gingiva, including the presence of thin double stranded extensions which may be related to the functional role of the gingiva or to the fact that the odontogenic apparatus is derived from surface epithelium in this region in the developing embryo, or both. Similar extensions have not been found in other oral epithelia.

Notes: A case of a peripheral odontogenic fibroma which contained aggregates of large granular cells is reported. These granular cells are similar to those previously described in the granular cell myoblastoma, congenital epulis and the granular cell ameloblastic fibroma.Deep extensions of the basal layer of overlying gingival epithelium, in double-strand fashion, are frequently observed in peripheral odontogenic fibromas. These strands closely resemble those seen in the tumor itself. On this basis, and as similar basal cell prolongations are seen in other jaw lesions, it is postulated that residual ectomesenchymal influence may be responsible for inducing the basal cell proliferations in a similar manner to that which occurs during early embryonic dental development. This, it is suggested, might possibly be the histogenesis of the odontogenic epithelial strands in the peripheral odontogenic fibroma.

Notes: Standardization is one of the greatest problems in assessing epithelial dysplasia, as is establishing the relative importance of different clinical and dysplastic features. In this study, 214 cases characterized historically by varying degrees of epithelial dysplasia, were analyzed for various clinical features: and representative sections were assessed histologically and graded according to the Smith-Pindborg standardized scoring system. Data were analyzed by computer Seven cases with scores of less than 10 were excluded as not dysplastic There were 85 cases (41%), with scores of 11–25 which were regarded as mild dysplasia; 60 (29%) with scores of 26–43 were regarded as moderate dysplasia; and 62 (30%) with scores of more than 45 which were reported as severe dysplasia. Peak frequency was in the 6th decade and the severe dysplasias were most frequent in the 8th decade The M:F was 2:1. Tongue (58 cases), lower lip (36), floor of mouth (32) and cheeks (26) were sites most commonly involved. Of 107 cases, 93 were described as homogeneous leukoplakia. 11 as speckled leukoplakia and 3 as crythroplakia. The distribution of mild, moderate and severe dysplasias did not differ significantly by ago. sex or race, Half of all cases involving floor of mouth and oropharynx were severely dysplastic, whereas most lesions occurring in check and alveolar mucosa/gingiva were mildly dysplastic; but differences were not significantly different. Severe grades of each dysplastic feature, as might be expected, occurred in lesions classified finally as ‘severe dysplasia’. Features which predominated in the severely dysplastic lesions were, in de-wending order, mitotic activity superficial to basal layer (98%); increased nucleo-cytoplasmic ratio (85%); increased mitotic activity (84%); pleomorphic cells and nuclei (79%); irregular epithelial stratification (75%); basal cell hyperplasia (73%); loss of polarity (72%); loss of intercellular adherence (71%) Other features, including bizarre mitoses (56%) occurred less frequently in the severe dysplasias. The use of a procedure of this kind is extremely valuable for purposes of standardization The question of whether the weighting of the different characteristics proposed by Smith and Pindborg is sufficiently accurate, or whether it is too subjective, should be tested Similarly, it is important to lest whether the histological criteria now used to assess the severity of dysplasia arc. in fact, those which arc of the greatest value in prognosing potential fur malignant change.

Notes: Presidential address delivered at the Second Meeting of the International Association of Oral Pathologists, The Netherlands, June 4th – 7th 1984.

Notes: Fibrous histiocytomas of the oral and maxillofacial regions arc rare. The present study analyzes a sample of 63 cases from the literature together with 7 personally observed cases. Age, sex, site, size, clinical behaviour, treatment and survival were evaluated and related to a histological classification based on that of Rosai (1981). Lesions were assessed for histological criteria which would place them in one of 2 groups: fibrous histiocytoma (FH) or pleomorphic fibrous histiocytoma (PFH). Within these 2 histological groups the cases were subdivided into clinically benign, aggressive or malignant lesions. Thirty-nine cases (56.0%) were classified as FH and 31 eases (44.0%) as PFH. The mean age of male patients with PFH was significantly higher than female patients with FH (t = 3.05; d.f. 37; p 〈 0.0025). Lesions in the PFH group involved bone more frequently than those in the FH group (Yale's Chi2 = 16.66; d.f. 1; p 〈 0.00025). Lesions involving bone for both histological groups were more likely to be aggressive or malignant than soft-tissue lesions (Yale's Chi2 = 29.9; d.f. 1; p 〈 0.00025). Soft-tissue lesions were usually less than 5 cm in greatest diameter. Radiographic features of malignancy for lesions with bone involvement is of prognostic importance regardless of the histological appearance of the lesion. The majority of the lesions under study were from the deep tissues of the oral and maxillofacial regions.

Notes: Abstract Histological changes were studied in the rat tongue for varying periods of time up to 14 days following the application of a cryoprobe to the dorsal surface of rat tongue. Within minutes of the application, focal subepithelial vesiculation and hyperemia occurred. At 3 h there was evidence of damage to capillary walls, resulting in hemorrhage. Arterioles and venules were thrombosed and there were degenerative changes in the muscle layer of their walls. At 6 h ventral epithelium showed evidence of damage. At this stage vessel walls were pavemented with neutrophilic polymorphonucleat leukocytes (PMN) and some of the latter were seen in the vessel walls. At 24 h abundant PMN, many of them necrotic, were present in the vessel walls, apparently unable to pass through them. At 48 h numerous PMN were seen adhering to degenerating muscle fibers. By 4 days necrotic changes extended through the full thickness of the tongue, but concurrently it was observed that the larger thrombosed vessels were becoming recanalized. At 5 days repair by granulation tissue was taking place and at 6 days the vasculature was virtually reconstituted. By 14 days healing was complete.

Notes: Abstract. A histological comparison has been made of the giant cells in 10 cases which had been diagnosed as central giant cell granuloma of the jaws and 10 cases diagnosed as giant cell tumor of long bone. The numbers of nuclei in each of 50 giant cells were counted in the 20 lesions. The giant cells were measured in order to compare their sizes in the respective lesions. It was found that the giant cells of the jaw lesions contained significantly fewer nuclei than those of the lesions in other bones. Secondly it was found that cells in the lesions of long bone have significantly larger dimensions than those in the jaw lesions. There was, however, an area of overlap. It was concluded that these data supported the view that giant cell tumor and giant cell granuloma are distinct entities. Some giant cell lesions of long bones are, however, morphologically indistinguishable from giant cell lesions of the jaws; and conversely giant cell lesions of the jaws are indistinguishable from some giant cell lesions of the long bones. It seems possible, therefore, that some jaw lesions are giant cell tumors and that some giant cell lesions outside the jaws are giant cell granulomas.