Divergences in diagnosing nodular breast lesions of noncarcinomatous nature.

Nodular breast lesions of noncarcinomatous origin are often of fibroepithelial origin. They may cause classification problems when they are hypocellular or hypercellular; the latter setting may also raise the differential diagnosis of phyllodes tumors. Thirty equivocal nodular breast lesions were collected and one hematoxylin and eosin slide from each was assessed by six pathologists with special interest in breast pathology. The overall reproducibility of classifying these lesions into categories of fibroadenoma, phyllodes tumor or anything else was moderate (kappa value: 0.48). The lack of a uniform nomenclature was not felt disturbing for hypocellular lesions, but the discordant diagnosis of tumors resembling or representing phyllodes tumors was acknowledged to require intervention, such as more obvious implication of guidelines and quality assurance programs aiming at assessing diagnoses and prognostic parameters.