Aims: Morphological, immunophenotypic and genetic heterogeneity amongst mantle cell lymphomas (MCLs) can lead to difficulties in diagnosis and management. The aim was to describe the clinical and pathological features of MCLs with aberrant expression of CD10.
Methods and results: Of 17 specimens from 13 patients, 14 expressed CD10 and three (presenting before or after a CD10+ specimen) did not. All expressed cyclin D1 and carried the t(11;14)(q13;q32)/CCND1-IGH translocation. Similar to non-selected MCL patients, most patients had disseminated disease and an adverse clinical course. Five specimens showed pleomorphic blastoid morphology and blastoid transformation was associated with a change in phenotype, including gain or loss of CD10. Additional phenotypic variations likely to cause diagnostic difficulty were present in eight specimens: five were CD5− and five (all CD10+) expressed Bcl-6. One Bcl-6+ case carried a BCL-6 translocation and three others had extra copies of the BCL-6 gene. Sequence analysis of the immunoglobulin heavy chain variable region in five cases showed only one to have low-level somatic mutation, indicating that they did not arise from germinal centre B cells.
Conclusions: Expression of CD10 by MCL is often associated with other variant morphological, immunophenotypic or genetic features, but does not reflect derivation from germinal centre B cells.