Our data indicate that prostasin may be implicated in normal prostate biology and is able to suppress prostate cancer invasion in vitro.

Ten adult white patients (21-75 years old; six women, four men) presented with large cell lymphoma of the liver. Each complained of abdominal pain and/or an abdominal mass, and five had B-symptomatology of weight loss, fever (one patient), and night sweats (three patients). At laparotomy (eight patients) or by computerized tomography, liver-spleen scan and lymphangiogram (two patients with percutaneous liver biopsy only), the liver was the sole site of involvement, although subsequent staging procedures revealed bone marrow involvement in three patients. Initial biopsy interpretation was incorrect in four cases which were diagnosed as poorly differentiated carcinoma. Although uncommon, the differential diagnosis of primary liver lymphoma should be entertained when patients present with solitary (three cases) or multiple (six cases) liver defects, particularly when alpha-fetoprotein and carcinoembryonic antigen levels are normal. One patient had diffuse hepatomegaly. Treatment included biopsy (eight patients) or resection (two patients) followed by combination chemotherapy. All patients are alive from 0 to over 10 years (mean, 2.4; median, 1.8 years): six in complete remission, two with less than 6-months follow-up, and two with recurrent lymphoma. Examination of this group of patients along with 19 cases identified in the literature suggests that this is a more treatable disease than primary liver carcinoma.

The cytopathologic characteristics of the inflammatory and lymphoid thyroid lesions as seen in fine-needle aspirate smears of 103 patients are reviewed, with emphasis on pitfalls and association with other neoplasms. The cytologic diagnoses were as follows: subacute thyroiditis, 3; Hashimoto's thyroiditis (HT) with or without Hürthle cell nodule, 77; HT and Hürthle cell tumor, 2; HT and follicular neoplasm, 3; HT and papillary carcinoma, 5; lymphoma, 3; HT and nodular colloid goiter, 10. Fourteen patients were operated. Five erroneous diagnoses were uncovered; inexperience was the main reason for the mistakes. The greatest diagnostic difficulties are encountered in cases of Hürthle cell nodules and malignant lymphoma, but mistakes are likely to disappear after reasonable experience. Thyroid antibodies are of no help in sorting diagnostic problems, because a positive titer is only corroborative evidence of underlying HT and does not rule out an associated tumor. Conversely, a negative titer does not discard the diagnosis of HT. The association of nodular colloid goiter and HT is depicted. Problems of sampling and staining technic are discussed.

Mesenteric fibromatosis (MF) and gastrointestinal stromal tumors (GISTs) are distinct lesions, but they often are confused with each other. Correct identification is essential because of their vastly different therapeutic and prognostic connotations. We reviewed 25 cases of MF with involvement of the wall of the gastrointestinal tract and found that GIST was the most common misdiagnosis (13 [52%]). MF was characterized by a spatially homogeneous proliferation of wavy spindle cells without atypia, associated with collagen deposition (often of the keloidal type), and an infiltrative border. Most cases displayed prominent muscular arteries and dilated, thin-walled veins. The mitotic count was relatively low, and no atypical mitotic figures were identified. These features are sufficiently characteristic of MF to permit distinction from GIST on the basis of routinely stained sections in the large majority of the cases, but immunohistochemical analysis provides a supporting role in the few equivocal cases.

Three-hundred and seventy intraoperative cytologies are presented and compared with synchronously performed frozen sections. Cytologic smears and frozen sections were misinterpreted in 1.6% and 0.8% of cases, respectively; the rate of diagnostic errors between the two techniques is comparable given the lack of experience with intraoperative cytology at the beginning of the study. Intraoperative cytology is a suitable technique for a variety of lesions, but it is most helpful in the field of neuro-oncological pathology, certain infectious diseases, lesions of the hematopoietic system, and most epithelial tumors. Cytologic smears afford better morphologic preservation and detail than frozen sections. Techniques are outlined and discussed. Diagnostic criteria of selected cases are presented, and pitfalls are analyzed.