Subtypes of human atypical lymph nodes, defined based on comparative morphological analysis.

Background. Lots of articles describe structure of lymph nodes with blood in their sinuses, but there are still many controversies between them due to the absence of single system of classification. Objective. The purpose of this work was to characterize the structure of human atypical lymph nodes and offer the new system of their classification. Methods. Atypical lymph nodes were taken during autopsy from patients who died due to cardiovascular or respiratory pathology. Standard histological methods were used including staining with hematoxylin and eosin. Results. Based on comparative morphological study we subdivided all atypical lymph nodes into three subtypes. I - Hemolymph node – it receives mixture of blood and lymph; during filtration through the system of sinuses all erythrocytes are eliminated, while efferent lymph vessels receive pure lymph. Such nodes are usually revealed close to kidneys and spleen. II – Hemal nodes – they receive blood through direct communication between blood vessels and sinuses; depending on the type of afferent vessel they are further subdivided into arterial and venous. Their efferent vessels contain blood with comparatively high content of leukocytes. III – Hyperemic lymph node – there are no afferent vessels bringing blood to the sinuses, but there are lots of dilated blood vessels with signs of hemoconcentration. All atypical lymph nodes contain different number of extravasated erythrocytes, assuming the possibility to filtrate blood antigens. Conclusion. Analyzing different types of human lymph nodes we offer a new system of their classification; the major criteria are summarized in the article