Numerous multivariate chemometric approaches have been developed for LC-UV data acquired using a diode-array detector (DAD), but these methods have not been widely exploited for LC-MS data. Principal component analysis (PCA) and subsequent axis rotation within the reduced factor space are assessed for LC-DAD and LC-MS data as approaches for estimating the number of components (i.e. the rank of the data) under a single chromatographic peak for compounds whose UV-spectra are very similar. Multivariate techniques for LC-DAD data are shown to suffer from inherent limitations of sensitivity for the minor components. The novel technique in LC-MS of plotting the rotated PCA data in two-dimensional factor space generates characteristic ion clusters, giving a visual criterion of peak purity. Single ion chromatograms produced subsequently confirm the profile of each coeluting component and give evidence of the degree of peak overlap. The application of this new chemometric technique to the detection of low levels of coeluting impurities by LC-MS is discussed as a novel approach for the validation of LC separations in pharmaceutical research and development.

Chromatography, Liquid↗

PubMedDate not supplied

Fine needle aspiration cytology of mammary pseudoangiomatous stromal hyperplasia. A case report.

BACKGROUND: Pseudoangiomatous stromal hyperplasia (PASH) is an unusual benign breast lesion that may occasionally present as a palpable mass. CASE: This report describes the fine needle aspiration cytology (FNAC) features of a case of mammary PASH that presented as a palpable mass. This is the second description of the FNAC features of this lesion and the first reported case in which a diagnosis of phyllodes tumor was considered. The aspirate was cellular and contained cohesive groups of cells in which there was a dual population of epithelial and myoepithelial cells. Occasional cellular stromal fragments were present, as were typical, bipolar, bare nuclei. Admixed with the bare nuclei were large numbers of plump, spindle-shaped cells, some with intact cytoplasm. Histologic examination of the excised mass showed features typical of PASH. CONCLUSION: Mammary PASH may present as a palpable mass and is likely to be encountered in FNAC specimens. This diagnosis should be considered when one is confronted with an aspirate containing cohesive epithelial groups, cellular stromal fragments and large numbers of single, spindle-shaped cells. These features on FNAC may result in consideration of a phyllodes tumor. The single, spindle-shaped cells may be a characteristic cytologic feature of PASH.

Adult↗