One thousand fourteen consecutive large intestines were removed at autopsy from persons over the age of 14 years and examined for diverticular disease. Diverticulosis was encountered in 194 patients (19 percent). The lesion appeared early in life, after the second decade. Men were affected more frequently than women before the age of 60 years. Chinese men had significantly more diverticular disease than Malayan men (P less than 0.01) and Indian men (P less than 0.02). Chinese men also had significantly more diverticular disease than Chinese women. There was a predominance of right colon involvement, with the disease affecting especially the ascending colon and cecum. This pattern was observed in all three major ethnic groups, and in both the Singapore-born and foreign-born Singaporeans. The cause of right-sided diverticulosis is unknown. It appears that, while adoption of the western diet may influence the prevalence of diverticular disease, the site of predilection is determined more by racial or genetic predisposition. All diverticula examined histologically were false, including 39 (20 percent) solitary diverticula. The distribution of solitary diverticula was similar to that of multiple diverticulosis. It is suggested that solitary and multiple diverticulosis are part of the spectrum of the same disease.

Squamous cell carcinoma (SCC) is a common and important primary cutaneous malignancy. On skin biopsies, SCC is characterized by significant squamous cell atypia, abnormal keratinization, and invasive features. Diagnostic challenges may occasionally arise, especially in the setting of small punch biopsies or superficial shave biopsies, where only part of the lesion may be assessable by the pathologist. Benign mimics of SCC include pseudoepitheliomatous hyperplasia, eccrine squamous syringometaplasia, inverted follicular keratosis, and keratoacanthoma, while malignant mimics of SCC include basal cell carcinoma, melanoma, and metastatic carcinoma. The careful application of time-honored diagnostic criteria, close clinicopathological correlation and a selective request for a further, deeper, or wider biopsy remain the most useful strategies to clinch the correct diagnosis. This review aims to present the key differential diagnoses of SCC, to discuss common diagnostic pitfalls, and to recommend ways to deal with diagnostically challenging cases.

Background. Expression of p53 protein has been described in a variety of human malignant tumors. Recent reports have also demonstrated its presence in benign and reactive lesions. The significance of p53 expression is unclear. Methods. This study examines the p53 expression in proliferative lesions of skin, including 6 pseudoepitheliomatous hyperplasia, 33 keratoacanthoma, and 45 squamous cell carcinoma, and to evaluate its significance. Results. p53 expression was observed in all of the six cases of pseudoepitheliomatous hyperplasia, 78.8% of keratoacanthoma, and 75.5% of squamous cell carcinoma. The staining pattern of pseudoepitheliomatous hyperplasia and keratoacanthoma was generally less intense and extensive compared with that of squamous cell carcinoma. A keratoacanthoma with nuclear atypia that showed strong and extensive p53 staining was also encountered. The perilesional skin in sun‐exposed sites often showed the presence of p53‐positive keratinocytes. Control skin taken from the buttock was negative for p53 protein. Conversely, p53 was often expressed in carcinomas arising from sun‐exposed as well as sun‐protected sites. p53 positivity involved mainly the undifferentiated cells at the base of the epidermis or periphery of tumor cords. Differentiated keratinized cells were not stained. p53‐positive fibroblasts were also noted in the inflammatory and granulation tissues of pseudoepitheliomatous hyperplasia. Conclusions. p53 expression in skin is common and appears to be an early event in a series of genetic alterations reflecting underlying actinic damage, which may lead to but does not necessarily indicate neoplastic or malignant transformation. Because p53 staining is seen in proliferative and undifferentiated cells and ceases to be expressed when the cells differentiate, it appears that the expression of p53 protein, mutant or wild‐type, is an indicator of immaturity and proliferative capacity of the cell rather than one of neoplasia or malignancy.

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The occurrence of malignant tumors at the site of metal implants is rare. The significance of this association is not settled. Its implications, however, are serious. A malignant fibrous histiocytoma arising at the site of an implant done 14 years ago for traumatic fracture of the femur in a 44‐year‐old man is reported. Previous reports are briefly summarized.

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Histologically classified biopsies from 83 women with invasive cervical carcinoma were analyzed by dot blot hybridization for human papillomavirus (HPV) types 16 and 18 infection. Sixty of the 83 (72.3%) were found to contain HPV DNA, of which 43 (51.8%) contained HPV 16 DNA, 12 (14.5%) contained HPV 18 DNA and 5 (6.0%) contained both HPV 16 and 18 DNAs. Southern blot analysis on 65 specimens gave similar results. Of 23 specimens negative by dot blot, 21 were tested by the polymerase chain reaction. Seventeen of the 21 were positive for HPV DNA, of which 13 contained HPV 16 DNA and 4 contained both HPV 16 and 18 DNAs. In all, 95.1% (77/81) were positive for HPV 16 and/or 18 DNA sequences.

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