Clindamycin-induced pseudomembranous colitis. Report of three cases

Cellular and tissue architecture of conjunctival membranes in epidemic keratoconjunctivitis

PURPOSE

Conjunctival membranes are differentiated from pseudomembranes by bleeding on removal. The authors sought to study the cellular constituents and extracellular structure of formed conjunctival exudates in epidemic keratoconjunctivitis (EKC), and to determine whether these represent true conjunctival membranes.

METHODS

Formed conjunctival exudates harvested from 2 patients with EKC were studied by immunohistochemistry. Adenoviral infection was evaluated by PCR.

RESULTS

Each patient's tears were PCR positive for adenovirus, but not HSV-I. Both conjunctival specimens contained a fibrinous stroma richly populated with cells positive for CD4, CD8, CD20, CD68, myeloperoxidase, and fascin. Both specimens also contained cells positive for CD31 and Tie-2, and demonstrated expression of transforming growth factor-β and vascular endothelial growth factor.

CONCLUSIONS

Conjunctival exudates in EKC contain a range of leukocytes representing both innate and acquired immune responses, along with angiogenic factors and proliferating endothelial cells. Therefore, true conjunctival membranes can and do form in EKC.

Solitary pulmonary papillomas in adults: a clinicopathologic and in situ hybridization study of 14 cases combined with 27 cases in the literature

Solitary endobronchial papillomas in adults are rare neoplasms. Only sporadic cases have been documented. The histologic classification of these tumors remains problematic, and little is known about their clinical behavior. The clinical and pathologic features of 13 endobronchial papillomas and a single endobronchiolar papilloma were reviewed. In situ hybridization for human papillomavirus (HPV) types 6/11, 16/18, and 31/33/51 was performed on seven cases. Twenty-seven additional well-documented cases were identified in a literature review. Human papillomavirus studies were performed in four of the previously reported cases. The 41 neoplasms combined from the Armed Forces Institute of Pathology and literature review were divided into three groups according to their histologic features. Thirty-one of 41 (76%) patients were men. The ages of the patients ranged from 26 to 74 years (median, 57 years). Three morphologically distinct histologic types were recognized; 27 squamous cell papillomas, 7 glandular papillomas, and 7 mixed squamous and glandular papillomas. Squamous papillomas: 23 of 27 (85%) patients were men, and the median age was 54 years. Six of eleven (55%) of these patients smoked. Twenty-six lesions were exophytic and a single lesion had an inverted pattern. Seven of 24 (29%) lesions featured cytologic atypia and 5 of 24 (14%) had viral cytopathic effect. Five of seven (71%) cases examined for HPV DNA were positive. Three of 18 (17%) recurred. Glandular papillomas: Four of seven (57%) patients were women. The mean age was 67 years. One of five (20%) patients smoked. Five lesions were central, and two were peripheral. Four lesions had columnar epithelium, and three had ciliated epithelium. One of six (17%) lesions recurred. Mixed papillomas: five of seven (71%) patients were men. The median age was 64 years. Three of five (60%) patients smoked. Three of seven (43%) lesions featured cytologic atypia. Four of five lesions were examined for HPV DNA and all were negative. No lesions recurred. This study demonstrates that solitary endobronchial papillomas can be separated into three distinct morphologic categories. Squamous cell and mixed papillomas are predominantly lesions of male smokers in their 6th decade. Although cytologic atypia is observed in many cases, the rarity of these tumors and difficulty in separating papillomas from endobronchial papillary squamous carcinomas make generalizations regarding the risk of progression to carcinoma tenuous at best. Human papillomavirus appears to play a pathogenetic role in some squamous cell papillomas, but not in mixed papillomas, yet its presence in the squamous lesions does not correlate with recurrence or malignancy. The first report of an inverted squamous cell papilloma indicates clinical features similar to the more common exophytic squamous cell papillomas. Glandular papillomas, the rarest of all endobronchial papillomas, are found in an older age group than squamous and mixed papillomas, and most-patients are nonsmokers. Based on these findings, all endobronchial papillomas should be completely excised.

Exophytic endobronchial epidermoid carcinoma

Exophytic endobronchial epidermoïd carcinoma is a rare clinical entity. The authors describe and systematically analyzed 34 cases, collected during 35 years. There was a preponderance of male patients; the mean age at presentation was 58 years. The tumors were nearly always at the T1N0 stage, and their prognosis was not better than that for other Stage I bronchogenic carcinomas. The findings suggest that they are a special subvariety of bronchogenic carcinoma, rather than tumor detected at an early stage.

Non-invasive bronchial epithelial papillary tumors

Nineteen papillary, non-invasive tumors arising from the bronchial epithelium but excluding carcinoid tumors are reviewed. Eight were solitary papillomas of which three were covered with a mixture of epithelial types. Seven were benign but one had a focus of carcinoma in situ. A similar change was seen in bronchial epithelium adjacent to a papilloma. Two cases of recurrent papillomas were seen and in one, carcinomatous changes eventually occurred. Two combined benign brochial cystadenomas with papillomas are described. One transitional celled papillary carcinoma in situ and five other papillary carcinomas in situ are described. One bronchial papilloma covered with dysplastic epithelium was considered an intermediate stage in the development of carcinoma in situ. Two papillary tumors may have arisen from peripheral bronchi or brochioles. Their lining cells resembled Clara cells, they grew by local expansion, and there was an absence of malignant features. The differential characteristics of two secondary carcinomatous polypoidal tumors are described.