Retikulinstain

Retikulinstain, commonly referred to in English as reticulin stain, is a histological staining technique used to visualize reticular fibers in tissue sections. Reticular fibers form a fine, three‑dimensional meshwork mainly composed of type III collagen and produced by reticular cells, providing structural support to parenchymal and hematopoietic tissues.

The method relies on silver impregnation to deposit silver onto the reticular fibers, which are then reduced to metallic silver to appear dark against a lighter background. The procedure is typically applied to formalin-fixed, paraffin-embedded sections and is one of several silver-based reticulin staining protocols, with Gordon and Sweets and Gomori reticulin stains being among the most widely used. A counterstain is usually applied to improve contrast and tissue architecture.

Reticulin staining is routinely used to assess tissue architecture in various organs, including the liver, bone marrow, spleen, lymph nodes, and the pancreas. In the liver, it helps delineate hepatic lobular architecture and identify changes associated with fibrosis or cirrhosis (such as thickened, intersecting reticulin bands forming nodules). In bone marrow, an increased or abnormal reticulin network can indicate marrow fibrosis, myeloproliferative disorders, or other hematologic conditions. The technique is also valuable for examining lymphoid tissue architecture and detecting disruptions in the reticular framework seen in certain neoplasms.

Limitations include sensitivity to fixation and processing, potential fading of the silver reaction, and the semi-quantitative nature of interpretation, which relies on experienced histopathologists. Immunohistochemical approaches for reticular fibers exist but are less commonly used for routine assessment.