Malignant classification

Chromosomal translocations have become a hallmark of many lymphomas and are helpful in the diagnosis and classification of lymphoid malignancies. NHL often involves extranodal sites and does not spread through contiguous lymph nodes. 

Bittner, M., et al., "Molecular Classification of Cutaneous Malignant Melanoma by Gene Expression Profiling," Nature, 406, 536-540 (2000). 

The division between benign and malignant is useful but too simple. To be a little more precise, we can add the classification of dysplastic tissue. Dysplastic cells are not yet fully malignant but are on their way to getting there. Finally, the term neoplastic is frequently used to describe malignant cells or tumors. So we have the sequence normal, benign, dysplastic, malignant (neoplastic). 

Southern blotting and polymerase chain reaction are being used for detecting B- and T-cell clonality in lymphoproliferative diseases, including mantle cell lymphoma and lymphoma of the breast (Medeiros and Carr, 1999). Molecular genetic tests are currently important ancillary tools for the diagnosis and classification of malignancy, and their role is likely to increase in the future. 

Alizadeh AA, Ross DT, Perou CM, van de Rijn M. Towards a novel classification of human malignancies based on gene expression patterns. J Pathol 2001 195 41-52. 

K12. Kipps, T. J., Advances in classification and therapy of indolent B-cell malignancies. Semin. 

Microarray-based gene expression profiling for gene and pathway discovery, functional classification of genes, and new tumor sub-classifications have also been applied to various other malignancies including lung, bladder and prostate cancer, and cutaneous melanoma (reviewed in Refs. 77 80). 

Wittekind C, Greene FL, Hutter RVP, Kliimpfinger M, Sobin LH, editors. TNM Atlas Illustrated Guide to the TNM Classification of Malignant Tumours. 5th ed, Hoboken Wiley-Lyss, 2005. 

This classification allows for seronegative patients to be classified as having PNS (no. 1). In addition, the set of definitions takes into consideration that new antibody specificities are still being characterized (no. 3). Different clinical subtypes are still being described in association with well-known antibodies, and such cases are also included. Finally, a negative screening for malignancy does not exclude PNS, as spontaneous remission is known to occur. As cancer is ultimately detected in the majority of patients with symptoms and a well-characterized antibody, the number of false positives is probably low (no. 4). 

Lymphomas are a heterogenous group of malignancies that arise from immune cells residing predominantly in lymphoid tissues. Differences in histology have led to classification as Hodgkin s and non-Hodgkin s lymphoma (HL and NHL, respectively), which are addressed separately in this chapter. 

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