Detection of a common mutation in factor V gene responsible for resistance to activated protein C causing predisposition to thrombosis

Hereditary predisposition to thrombosis due to activated protein C resistance (APCR) has been attributed to a missense mutation in the factor V gene at nucleotide 1691 (G to A), causing replacement of arginine at codon 506 with glutamine. Using an RFLP-PCR assay to detect this mutation, we measured a prevalence of 3.3% in healthy Caucasians and 1.25% in healthy African-Americans. In addition, we evaluated a total of 90 consecutive specimens submitted to the coagulation laboratory at the Medical College of Virginia for the presence of this mutation. We compared our results for 78 of these specimens with the values measured by a modified partial thromboplastin assay, the COATEST. Twelve of the 90 samples could not be tested using the COATEST because the patients were undergoing anticoagulant therapy. One of the latter 12 specimens was positive by the RFLP-PCR test. Using the genetic test as the definitive assay and the cutoff value established for distinguishing between normal and abnormal results by the COATEST, the COATEST had a sensitivity of 50% and specificity of 93% for the detection of factor V mutation. Analysis of the 90 samples stratified by ethnic groups revealed a frequency of mutation of 13.3% for Caucasians and 6.88% for African-Americans, although with the present sample size, the difference was not statistically significant. Although the COATEST is technically simpler to perform than the genetic test for diagnosing the presence of the factor V mutation, its use for this purpose is limited due to low sensitivity. Thus where this disorder is clinically suspected, submission of the specimen directly for genetic testing by RFLP-PCR or equivalent assay should be considered. J. Clin. Lab. Anal. 11:328–335, 1997. © 1997 Wiley-Liss, Inc.     

Pituicytoma with pleomorphism: A case report with cytological findings

Pituicytoma is a rare neoplasm, arising in the posterior pituitary or in the hypophyseal stalk, and its cytological findings have not yet been well-described. We have experienced a case of pituicytoma, which was difficult to diagnose intraoperatively, because of its cellular pleomorphism. A tumor measuring 18 mm in maximum diameter was found at the sella turcica in a Japanese woman in her forties. Both intraoperative crush cytology and histology of the resected tumor showed pleomorphic spindle or round cells, including multinucleated cells. Tumor cells were positive for TTF-1, S-100 protein, and vimentin, partially positive for glial fibrillary acidic protein and epithelial membrane antigen, and negative for synaptophysin, hormones of the anterior pituitary gland, CD34, Olig2, PAX8, and napsin A. Ki-67 labeling index was 2.0%. Tumors included in the differential diagnosis in general are pituitary adenoma, craniopharyngioma, germinoma, and metastatic tumor on the radiological standpoint, and pilocytic astrocytoma and meningioma on the cytological standpoint. However, our case was difficult to differentiate especially from high-grade glioma only by morphology, and immunohistochemistry including TTF-1 was helpful.