Tissue Molecular Techniques in Lymphoproliferative Disorders: Contribution to Diagnosis, Prognosis, Therapy and Follow up. Bridging Molecular Pathology with Clinical Practice

Molecular data are an essential component in the study of neoplasias. The important and incumbent role of molecular pathology in clinical practice is evident in the last classification of the World Health Organization (WHO) in 2008 for the tumors of the hematopoietic and lymphatic tissues, where incorporated are all the new molecular data and entities defined by genetic criteria. It is now recognized that a genetic abnormality can be considered diagnostic for an entity. At the same time the diagnostic approach of lymphoproliferative disorders is multifactorial; morphological, immunohistochemical and genetic characteristics, along with clinical data, are required for the diagnosis.In the hematopathology laboratory, the molecular techniques used in every day practice regarding tissues are polymerase chain reaction (PCR) and in situ hybridization (ISH) using either a fluorescence chromogen (FISH) or plain chromogenic in situ hybridization (CISH). The usefulness of these molecular techniques in lymphoproliferative disorders is to document B- or T- cell clonality, including diagnosis of lymphoma, differential diagnosis between a reactive lymphadenopathy and lymphoma, staging, follow up, and detection of early stages of a lymphoma, and to detect genetic abnormalities, numerical or structural, diagnosis of certain lymphoma subtypes encompassing distinction of subtypes within the same entity with different biological behavior, prognostic indices, and indices of response to certain therapeutic regimens