No abstract

Fine-needle aspiration (FNA) is a valuable technique to use in the evaluation of breast lesions; however, inadequate and discrepant diagnoses do occur. To identify the source and nature of inaccuracies related to the method we studied 39 cases in which FNA posed diagnostic problems. These problems could be attributed to sampling errors (71.8%), to the criteria of adequacy we use at our institution (25.6%), and to interpretation (2.6%). The nature of the breast lesion (68%) was the most common cause of inadequate sampling, followed by the experience of the aspirator (32%).

In patients with MG who underwent MMT, bcl-2, bax, and Ki67 expression correlates positively or reversibly with the microscopic findings of thymus. Increased apoptosis and proliferation accompany advanced disease stage and possible worse prognosis.

The light microscopic and ultrastructural features of five asymptomatic peripheral carcinoids presented as distinct pulmonary solitary nodules are described. By conventional microscopy the tumors displayed a variety of histologic patterns, the most unusual one showing tumor cells embedded in a richly vascular hyalinized stroma and forming papillary structures or cystic spaces lined by low cuboidal cells which ultrastructurally bore a strong resemblance to intermediate or transitional forms between types I and II pneumocytes. A striking feature of these tumors was their rich vasculature associated with a marked perivascular sclerosis composed of basement membrane‐like material and collagen fibrils most likely produced by the increased numbers of pericytes surrounding these sclerotic vessels. The clinical implications, biologic behavior, and association of these tumors with other pulmonary neoplasms are also discussed.