My approach to the diagnosis of mesothelial lesions.

Mesothelial lesions pose considerable diagnostic challenges not only because benign tumours, reactive proliferations and malignant mesothelioma can mimic one another, but also because the morphological patterns displayed by malignant mesothelioma can simulate a variety of epithelial and non-epithelial malignancies. Immunohistochemical markers can aid in distinguishing epithelioid malignant mesothelioma from metastatic adenocarcinoma, but because no single marker reliably separates all cases, a panel of stains is recommended. Immunohistochemical studies are of more limited value in sarcomatoid malignant mesothelioma, and other features often play an essential role. The separation of reactive mesothelial proliferations from malignant mesothelioma on small biopsy can be quite difficult, as distinguishing features, such as stromal invasion, often cannot be adequately assessed. In adequately sampled lesions, however, the distinction between malignant mesothelioma, benign mesothelial proliferations and other tumours can be achieved in most cases by using a carefully integrated approach that incorporates clinical and radiographic data, immunohistochemical studies and, in selected cases, histochemical and ultrastructural techniques.

Well-differentiated papillary mesothelioma.

Well-differentiated papillary mesothelioma is an unusual variant of epithelial mesothelioma considered to be of low malignant potential. The majority of previously reported cases developed in the peritoneum of young women without a history of asbestos exposure. The authors report 14 cases of well-differentiated papillary mesothelioma, seven of which originated in the pleura, six in the peritoneum, and one in the tunica vaginalis. Eleven of the patients were male and three were female, with an average age at presentation of 58 years (range 32-82 years). Six of the patients had a quantifiable history of asbestos exposure. Of the nine cases with complete follow-up, six had clinically indolent disease, one showed resolution after adjuvant chemotherapy, one pursued an aggressive course, and one died of other causes. These findings indicate that well-differentiated papillary mesothelioma is a rare variant of mesothelioma with a variable clinical prognosis that is etiologically related to asbestos exposure in some cases.

Fine needle aspiration cytology of mucinous cystadenocarcinoma of the lung: report of a case with radiographic and histologic correlation.

BACKGROUND: Mucinous cystadenocarcinoma of the lung is an uncommon tumor. Because it contains relatively few neoplastic cells relative to the amount of mucin produced, diagnosis of this entity, particularly on small specimens, is exceedingly difficult. CASE: The diagnosis of adenocarcinoma was made on transthoracic fine needle aspiration from a patient with a right upper lobe lung mass. Abundant mucoid material suggested a mucin-producing neoplasm. Histopathology revealed a mucinous cystadenocarcinoma with focal mucinous bronchoalveolar carcinoma. CONCLUSION: The presence of copious extracellular mucin in fine needle aspirates from the lung otherwise diagnostic of adenocarcinoma should raise the possibility of a mucinous tumor. In particular, the diagnosis of mucinous cystadenocarcinoma may be suggested in cases that have a cystic appearance on imaging studies.

Unexpected autopsy findings arising from postmortem ocular examination.

BACKGROUND: A full autopsy at our institution includes removal of the eyes for pathologic examination. To our knowledge, the rate of ophthalmic findings at autopsy has not been documented previously. DESIGN: We retrospectively reviewed 277 consecutive autopsies conducted between 1995 and 1999 in which the eyes were removed for examination. Ophthalmic findings were placed in the following categories: I, major findings included those that contributed to the patient's death, would have changed patient management, and/or may have important medical implications for close relatives; II, expected findings after ophthalmologic surgery and minor findings that may have eventually required treatment; and III, incidental findings. RESULTS: Major findings (category I) were found in 32% of autopsies. Minor findings (category II) and incidental findings (category III) were documented in 62% and 34% of autopsies, respectively. Only 14% of autopsies revealed no ophthalmologic diagnoses. CONCLUSION: In our series, postmortem ocular examination revealed a number of important findings, including several heritable and rare conditions. Eighty-six percent of autopsies disclosed at least one pathologic ophthalmologic finding, approximately one third of which demonstrated findings significant enough to have likely required management. Diabetic retinopathy was the most frequent major finding. Malignant melanoma of the choroid was the most commonly found intraocular neoplasm. Chronic uveitis was the most common minor finding. We conclude that important, often unexpected ophthalmic findings are frequently encountered at autopsy, underscoring the relevance of routine postmortem examination of the eyes.

Progesterone receptor activity in leiomyomatosis peritonealis disseminata.

Leiomyomatosis peritonealis disseminata (LPD) is a rare condition that primarily affects women of reproductive age. Immunohistochemical studies were performed in four cases: LPD from a premenopausal woman on oral contraceptives (one case); LPD associated with postpartum massive ectopic decidual reaction (one case); and LPD from a perimenopausal and a postmenopausal woman. Progesterone receptor activity was present in nine of nine cases, and eight of eight cases were strongly positive for vimentin; reactivity for cytokeratin was uniformly negative. Most cases had a pattern of staining typical of smooth muscle tumors with expression of desmin, smooth muscle actin, and muscle-specific actin. Although estrogen receptor was detected in most cases, reactivity was notably absent (one case) or weak (one case) in nodules with a prominent decidual reaction. Expression of CD 34, a marker for which LPD staining characteristics have not been previously reported, varied from absent to weak. Peritoneal nodules from the postmenopausal woman lacked staining for both estrogen receptor and desmin, smooth muscle actin and muscle-specific actin were only focally expressed, whereas staining for CD 34 was focally intense. Uterine myometrium and leiomyomata were positive for progesterone and estrogen receptor, vimentin, desmin, smooth muscle actin, and muscle-specific actin. Cytokeratin expression was absent. CD 34 exhibited weak staining in leiomyomata, but was absent from myometrium. Progesterone receptor appears to be uniformly expressed in LPD nodules from premenopausal and postmenopausal women, a finding supporting the contention that hormones influence the development of LPD in all cases, regardless of menopausal status.