[Reactive Lymphadenopathies]

Reactive Lymphadenopathies Abstract. A lymphadenopathy, i. e. lymph node enlargement, is a relatively frequent finding in both children and adults and in the vast majority of cases corresponds to reactive changes that disappear spontaneously within several weeks. In cases with a marked or persistent enlargement of the lymph node or an unusual clinical presentation, further investigation is warranted, which relies, in addition to clinical, laboratory and radiological findings, upon the histological examination of the enlarged lymph node - being the crucial task thereof the discrimination between malignant and benign processes. The capital importance of this is illustrated by the fact that reactive lymphadenopathies mistaken for lymphomas are among the most frequently misdiagnosed types of cancer. On the other hand, the recognition of more or less specific histopathological patterns of reactive changes serves to narrow down the various potential causes, including those that would otherwise only be recognised by the use of resource-intensive ancillary techniques. Hence, the narrower the differential diagnosis based on the histopathological examination is, the more targeted and efficient the application of these techniques can be. This review provides a summary of the essential histopathological features of some of the most common and best-characterised reactive lymphadenopathies. After a description of the most important morphological patterns of lymph node changes, we will discuss individual clinical pictures, from infectious and idiopathic processes to autoimmune diseases and drug-associated changes.