Ki67 staining pattern as a diagnostic tool in the evaluation of lymphoproliferative disorders

Bryant, R J
Banks, P M
O'Malley, D P

Department of Pathology, College of Medicine, University of Vermont, Burlington, VT, USA (Bryant)
¹Department of Pathology, Carolinas Medical Center, Charlotte, NC, USA
²Division of Hematopathology, Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA

Address for correspondence: Ronald J Bryant MD, Department of Pathology, College of Medicine, University of Vermont, 89 Beaumont Ave., Burlington, VT 05405, USA. e-mail: [email protected]

Abbreviations: CAS, Castleman's disease; FH, follicular hyperplasia; FL, follicular lymphoma; FVFL, floral variant of FL; MPF, mixed pattern hyperplasia; MZL, marginal zone lymphoma; PTGC, progressively transformed germinal centre; SLL, small lymphocytic lymphoma

Date of submission 7 July 2005, Accepted for publication 6 October 2005

Histopathology 48(5):p 505-515, April 2006.

Aims

To evaluate a group of lymphoid proliferations using only Ki67-stained slides to determine the value of the pattern of proliferating cells in diagnosis. Ki67 immunohistochemistry allows evaluation of the distribution of proliferating cells in addition to simply determining the proliferation rate of cells.

Methods and results

Three observers, using a Ki67-stained slide only, studied 149 cases from five diagnostic groupings: follicular hyperplasia, mixed pattern hyperplasia, localized Castleman's disease, follicular lymphoma and marginal zone lymphoma. The sensitivity for benign lesions varied from 94% to 97% among the three observers. Follicular lymphomas were recognized as neoplastic with a sensitivity of 96% and 100% by two of the observers. Marginal zone lymphoma was recognized as neoplastic in 67–73% of cases.

Conclusions

The Ki67 stain alone is a powerful tool for distinguishing benign from malignant proliferations within the selected groups. Nuances and pitfalls in the interpretation of Ki67 staining pattern are discussed.