Blastic transformation of mantle cell lymphoma: genetic evidence for a clonal link between the two stages of the tumour

Blastic Transformation of a Mantle Cell Lymphoma Presenting as an Enlarging Unilateral Orbital Mass

Mantle cell lymphoma (MCL) is an uncommon form of non-Hodgkin lymphoma predominantly affecting male individuals of advanced age. Approximately 1-9% of cases of lymphoma affecting the orbital and ocular adnexal regions are attributed to MCL. We describe the case of a 65-year-old man with a 24-year history of MCL with initial remission followed by multiple relapses who presented with acute-onset binocular diplopia and proptosis of the left eye. Subsequent imaging demonstrated a new left superior orbital mass. Biopsy of the mass revealed two clonally related, yet distinct cellular components demonstrating the classical mantle cell morphology and large cells that appeared to have transformed to the blastoid variant of MCL. Transformation of classical MCL to the blastoid variant of MCL is rare, with few reports in the literature. The blastoid variant of MCL tends to be aggressive and associated with a poor prognosis. The case we describe represents perhaps the first report of MCL transformation observed in the orbit.

Cytopathology in the diagnosis of lymphoma

FNA is a simple, safe, and an inexpensive sampling technique that plays an important role in the evaluation of lymphadenopathy. The key to enhancing the accuracy of FNA diagnosis of lymphoma is the multi parameter approach in which the cytomorphologic features are evaluated in correlation with the results of ancillary studies and clinical context. A full understanding of the current lymphoma classification, clinical features associated with each lymphoma subtype and the impact of the diagnosis on patient management is essential in FNA diagnosis of lymphoma. It is also important to recognize the limitations of FNA in the primary diagnosis of some subtypes of lymphoma, and tissue biopsy should be recommended for a definitive diagnosis and subclassification in such cases.

Mantle cell lymphoma shows three morphological evolutions of classical, intermediate, and aggressive forms, which occur in parallel with increased labeling index of cyclin D1 and Ki-67

Although the 2008 World Health Organization classification defines two subtypes of mantle cell lymphoma (MCL), classical and aggressive, we often encounter MCL with both features in the same site. We named this feature "MCL with focal aggressive form (intermediate MCL)". In the present study, we reclassified 237 patients with cyclin D1 (CCND1)-positive MCL on the basis of the concept of intermediate MCL, and analyzed the correlation of this reclassification with immunohistochemical detection of CCND1, Ki-67, p53, p27(Kip1), and p21(WAF/Cip1). The median overall survival was 77, 31, and 18 months for classical, intermediate, and aggressive MCL, respectively, showing a statistically significant difference (P < 0.0001). The expression levels of CCND1, Ki-67, p53, and p21(WAF/Cip1) in aggressive MCL (mean 80.1 +/- 27.8%, 73.7 +/- 28.9%, 31.0 +/- 69.0%, and 10.4 +/- 24.8%, respectively) were higher than those in classical MCL (mean 58.1 +/- 36.7%, 25.2 +/- 25.5%, 6.5 +/- 24.3%, and 2.5 +/- 13.0%, respectively) and intermediate MCL (mean 75.7 +/- 31.4%, 30.8 +/- 33.3%, 21.0 +/- 57.4%, and 4.8 +/- 16.5%, respectively). Significantly different levels of Ki-67 and p21(WAF/Cip1) were only recognized between intermediate and aggressive (P < 0.05 and P < 0.0001, respectively), whereas those of CCND1 and p53 were only between classical and intermediate (P < 0.0001 and P < 0.05, respectively). There were no significant differences in p27(Kip1) among the three groups. The subsequent discriminant analysis with independent prognostic factors clearly demonstrated that the morphological evolution of MCL occurs in parallel with increased labeling index of CCND1 and Ki-67. The diagnosis of intermediate MCL thus proved to be of major significance and should enable the design of more tailored therapies.

Sequence analysis proves clonal identity in five patients with typical and blastoid mantle cell lymphoma

Mantle cell lymphoma (MCL) is typically composed of small irregular lymphoid cells. Blastoid variants, composed of lymphoblast-like (classic type) or large (pleomorphic type) cells, arise de novo or in patients with typical MCL. Although it has been assumed that blastoid variant represents histologic transformation of typical MCL, the clonal relationship between the two tumors has rarely been assessed at the molecular level. We identified five patients with typical MCL who subsequently developed the blastoid variant. There were two men and three women with a median age of 65 years (range, 34-70) at diagnosis of typical MCL involving lymph nodes. The median interval between typical and blastoid MCL was 36 months (range, 11-103). Subsequent blastoid variant MCL involved soft tissue (two), lymph node (one), ileum (one), or rectum (one). All typical and blastoid neoplasms were positive for CD20, cyclin D1, and monotypic surface immunoglobulin light chain, and all typical cases were positive for CD5. Two blastoid neoplasms lost CD5 expression, one of which aberrantly expressed CD10. Immunostaining for Ki-67 showed a median proliferative fraction of 20% in typical and 70% in blastoid neoplasms. Sequence analysis of the VDJ regions of the rearranged IgH allele proved clonal identity in each set of paired samples in all five patients. These results support the concept that blastoid MCL arising in patients with typical MCL represents histologic transformation of the original neoplastic clone.

Blastoid and common variants of mantle cell lymphoma exhibit distinct immunophenotypic and interphase FISH features

AIMS

The recognition of blastoid variant (BV) of mantle cell lymphoma (MCL) is based on morphological criteria. Our aim was to analyse 18 MCL cases including four BV-MCL for their clinicopathological features, proliferation index, cyclin D1 and CDK4 expression and interphase fluorescence in-situ hybridization (FISH) pattern.

METHODS AND RESULTS

BV-MCL versus common MCL was characterized by a shorter overall duration of response after first-line therapy (11 months versus 28 months) and shorter overall survival (20 months versus 42 months). Interphase FISH showed a t(11;14) fusion pattern in all MCL tested cases. However, the four blastoid cases were characterized by extra copies of CCND1 signals. Using additional probes of chromosomes 11, 18, 21, these signals were shown to be the result of hypotetraploidy and not of a specific amplification of the normal or the translocated CCND1 allele. Moreover, the BV-MCL cases were characterized by a combined high percentage of cells expressing cyclin D1 and/or CDK4 with a proliferation (MIB-1-Ki67) index above 50%. Such features allowed the recognition of areas of large cell transformation in the case of secondary BV-MCL.

CONCLUSIONS

Since distinction between BV and common MCL is of clinical relevance, our data underline the need to add phenotypic and cytogenetic criteria to cytomorphology for a better recognition of BV-MCL.

Histopathology, cell proliferation indices and clinical outcome in 304 patients with mantle cell lymphoma (MCL): a clinicopathological study from the European MCL Network

Mantle cell lymphoma (MCL) is a distinct lymphoma subtype with a particularly poor clinical outcome. The clinical relevance of the morphological characteristics of these tumours remains uncertain. The European MCL Network reviewed 304 cases of MCL to determine the prognostic significance of histopathological characteristics. Cytomorphological subtypes, growth pattern and markers of proliferation (mitotic and Ki-67 indices) were analysed. In addition to the known cytological subtypes, classical (87.5%), small cell (3.6%), pleomorphic (5.9%) and blastic (2.6%), we identified new pleomorphic subgroups with mixtures of cells (classical + pleomorphic type; 1.6%) or transitions (classical/pleomorphic type; 1.6%), which, however, did not differ significantly in overall survival time. Exactly 80.5% of cases displayed a diffuse growth pattern, whereas 19.5% of cases had a nodular growth pattern, which was associated with a slightly more favourable prognosis. A high proliferation rate (mitotic or Ki-67 indices) was associated with shorter overall survival. Cut-off levels were defined that allowed three subgroups with different proliferation rates to be discriminated, which showed significantly different clinical outcomes (P < 0.0001). Based on this large clinicopathological study of prospective clinical trials, multivariate analysis confirmed the central prognostic role of cell proliferation and its superiority to all other histomorphological and clinical criteria.

Growth pattern and distribution of follicular dendritic cells in mantle cell lymphoma: a clinicopathological study of 96 patients

Mantle cell lymphoma (MCL) is an aggressive lymphoma with accepted risk factors such as proliferation markers. To date, the different follicular dendritic cell (FDC) patterns have never been analyzed in comparison with the overall survival time. Lymph node biopsy specimens from 96 patients were analyzed by conventional morphology and immunohistochemistry with antibodies against cluster differentiation (CD)20, CD5, CD23, cyclin D1, and FDC (Ki-M4P). Two groups can be distinguished with different FDC patterns: a nodular pattern in 79 cases and a diffuse pattern in 17 cases. A Kaplan-Meier analysis revealed significantly better survival for the nodular group (p=0.0312). This group was subdivided into a group with a nodular FDC pattern similar to the FDC distribution in primary follicles (PF-nodular in 72 cases) and one with a nodular FDC pattern resembling the colonization of germinal centers (GCs) by tumor cells (GC-nodular in seven cases). A Kaplan-Meier analysis showed that patients with MCL with a PF-nodular FDC pattern had a significantly better clinical outcome than patients with the other two patterns (p=0.0033). If only cases with classical cytology (n=79) were analyzed (blastoid types excluded), patients with a PF-nodular FDC pattern had a better clinical outcome (p=0.0008). The distribution of FDC in MCL is a diagnostic tool for identifying patients with a better clinical prognosis.

Blastoid variant of mantle cell lymphoma: late progression from classical mantle cell lymphoma and quantitation of minimal residual disease

OBJECTIVES

Classical mantle cell lymphoma (MCL) and its blastoid variant (MCL-BV) are characterized by an extremely poor prognosis. Long-time survivors are rare, only very few patients with an overall survival over 10 years have been reported. We present a case of a 41-year-old male with a 12 yr history of MCL stage I to show, that very late relapses in MCL are possible and may present as a transformation into an aggressive blastoid variant and to illustrate the value of quantitative minimal residual disease (MRD) monitoring for treatment guidance.

METHODS

Diagnostic lymph node and bone marrow samples were investigated by immunohistochemistry. Clonality analysis was performed by immunoglobulin heavy chain gene (IGVH) and t(11;14) PCR. The MRD assessment was done by real-time quantitative PCR (RQ-PCR) on available follow-up samples.

RESULTS

By histologic review and sequencing of the clonal IGVH and t(11;14) PCR products we demonstrated a common clonal origin of the leucemic MCL-BV and the classical MCL diagnosed 12 yr earlier. Quantitative MRD assessment revealed significant MRD levels after intensive conventional chemotherapy including Rituximab. Therefore, treatment was early intensified by myeloablative radio-chemotherapy and allogeneic peripheral stem cell transplantation from an unrelated HLA-identical donor. This did not translate into a sustained remission as reflected by persisting MRD levels after transplantation and the patient died from rapid progressive disease 3.5 months after transplant.

CONCLUSION

This report presents a rare case of long-term survivor of MCL with a progression of the original MCL cell clone to MCL-BV and demonstrates the clinical value of quantitative MRD assessment for optimized therapeutic management.

Cell cycle alterations in the blastoid variant of mantle cell lymphoma (MCL-BV) as detected by gene expression profiling of mantle cell lymphoma (MCL) and MCL-BV

Overexpression of cyclin D1 is necessary but by itself insufficient for the development of mantle cell lymphoma (MCL). To identify pathways in the pathogenesis of MCL and the blastoid variant (MLC-BV), we compared the gene-expression profiles of microdissected normal mantle cells, MCL, and MCL-BV by oligonucleotide microarrays and quantitative reverse transcriptase PCR (QRT-PCR). We identified and confirmed the overexpression of several genes in MCL-BV that are involved in the cell cycle control at the G1/S and G2/M checkpoints or inhibit apoptotic cell death. The highly expressed cyclin dependent kinase 4 (CDK4) is a cell cycle kinase that associates with cyclin D1 for the progression through the G1/S checkpoint, whereas overexpression of cdc28 protein kinase 1 (CKS1) blocks the inhibition of the cyclin D1/CDK4 complex by the CDK inhibitor p27/Kip1. Other highly expressed genes in MCL-BV that promote the cells through the G1/S-checkpoint include the oncogenes B-Myb, PIM1, and PIM2, and passage through the G2/M-checkpoint is enhanced by high levels of cdc25B. Furthermore, two highly expressed genes that inhibit apoptosis are defender against cell death (DAD1) and RSK1. In summary, our microarray and QRT-PCR analyses identified several candidate genes whose expression increased when comparing normal follicular mantles with MCL and MCLBV, suggesting a potential pathogenic role in the evolution of MCL-BV.

Pathology of lymphoma progression

Reflecting the stepwise process of oncogenesis, lymphomas may cumulatively develop a more aggressive phenotype during the course of disease, a process referred to as lymphoma progression. Although morphological, clinical and biological aspects of lymphoma progression do not always overlap, changes in lymphoma morphology frequently indicate alterations in the clinical and biological behaviour of the disease. Indolent and aggressive lymphomas in disease progression can either be clonally related or represent clonally unrelated neoplasms. We propose to use the term 'lymphoma progression' in a biological sense denoting only clonal development of and within a lymphoma entity. The term 'composite lymphoma' should be used as a merely descriptive morphological designation for different lymphoma entities in one individual irrespective of clonal relationship. Many types of aggressive B-cell non-Hodgkin's lymphomas and Hodgkin's lymphomas are reported to secondarily develop in lymphoma progression. Genetic changes associated with lymphoma progression frequently abrogate the differentiating effects of alterations occurring in indolent lymphomas, leading to increased cell proliferation. Within different lymphoma entities, high-risk disease variants mimicking lymphoma progression exist.