The search for meaningful prognostic markers in diffuse large B-cell lymphoma

Prognostic Significance of in situ Phenotypic Marker Expression in Diffuse Large B-cell Lymphomas

Diffuse large B-cell lymphomas (DLBCL) are the most common lymphoid malignancies, and encompass all malignant lymphomas characterized by large neoplastic cells and B-cell derivation. In the last decade, DLBCL has been subjected to intense clinical, phenotypic and molecular studies, and were found to represent a heterogeneous group of tumors. These studies suggested new disease subtypes and variants with distinct clinical characteristics, morphologies, immunophenotypes, genotypes or gene expression profiles, associated with distinct prognoses or unique sensitivities to particular therapy regimens. Unfortunately, the reliability and reproducibility of the molecular results remains unclear due to contradictory reports in the literature resulting from small sample sizes, referral and selection biases, and variable methodologies and cut-off levels used to determine positivity. Here, we review phenotypic studies on the prognostic significance of protein expression profiles in DLBCL and reconsider our own retrospective data on 301 primary DLBCL cases obtained on a previously validated tissue microarray in light of powerful statistical methods of determining optimal cut-off values of phenotypic factors for prediction of outcome.

The immunohistochemistry laboratory: looking at molecules and preparing for tomorrow

CONTEXT

Surgical and subspecialty pathologists rely heavily on the patient's clinical context, imaging studies, morphology, and on ancillary studies such as immunohistochemistry (IHC), cytogenetics, and molecular diagnostics in arriving at accurate, contemporary diagnoses. Lymphoma/leukemia classification has led the way in the number of antibodies used in IHC algorithmic diagnostic approaches to distinguish more than 40 diseases. As the era of genomics, transcriptomics, proteomics, and targeted pathway therapeutics unfolds-and as infusion of federal funds to programs such as Accelerating Clinical Trials of Novel Oncologic PathWays (ACTNOW) requires that correlative biomarker assays be performed in Clinical Laboratory Improvement Amendments of 1988 (CLIA)-certified IHC laboratories-we face changes and challenges for the future.

OBJECTIVE

To discuss the laboratory, pertinent daily diagnostic, prognostic, and therapeutic uses of IHC, and future directions and challenges.

DATA SOURCES

Recent literature review and ongoing current activities in our laboratory and institution.

CONCLUSIONS

Meticulous attention at the microscope by expert subspecialty pathologists using ancillary methods is important in making correct diagnoses. Awareness of the literature and interactions with our research colleagues, including clinical, basic, and translational scientists, continue to expand our insights into and understanding of complex diseases; this will ultimately provide prognostic information to assist in appropriate clinical management of our patients and development of new targeted or combination therapies. Multimodality correlations will continue, with morphology, imaging data, immunophenotyping, and genetics as well as steadily increasing integration of pathway signaling, genome, sequenome, transcriptome, and proteome data used in clinical settings.

Differential expression of the CD10 antigen (neutral endopeptidase) in primary versus metastatic malignant melanomas of the skin

The CD10 antigen is a neutral endopeptidase expressed by a variety of mesenchymal tumours (haemopoietic or not), including a subset of malignant melanomas. We investigated the expression of CD10 in formalin-fixed, paraffin-embedded tissue specimens of 72 cutaneous melanomas (28 primary, 26 metastatic to the skin and 18 lymph node metastases). The CD10 antigen was expressed by 18 of the 26 (69%) and 11 of the 18 (61%) melanomas metastatic to the skin or lymph nodes, respectively; in contrast, only six of the 28 primary melanomas (21.4%) expressed appreciable CD10 reactivity, and expression was usually lower (in terms of the percentage of immunoreactive cells) than that found in metastatic tumours. The sensitivity, specificity, and positive and negative predictive values of CD10 positivity for metastatic malignant melanoma were calculated to be 0.66, 0.79, 0.83 and 0.6, respectively. Our results suggest that the CD10 antigen is upregulated during the process of metastasis in melanomas. From a diagnostic point of view, the expression of CD10 appears to be an additional feature for the histological differential diagnosis between primary and metastatic melanomas.