The reticulin stain is extensively used in the histopathology laboratory for staining liver specimens, but can also be used to identify fibrosis in bone marrow core biopsy specimens. Fibrosis or the excess formation of fibrous tissue is commonly demonstrated in bone marrow biopsy specimens that have myeloproliferative disorders (conditions that cause blood cells to grow abnormally in the paraffin processed bone marrow) such as polycythemia vera, primary or idiopathic myelofibrosis, essential thrombocytosis, or chronic myeloid leukemia (CML). Additionally, fibrosis can be noted on bone marrow specimens that have significant tumor metastasis. Because several neoplastic and non-neoplastic pathologic conditions can be associated with increased reticulin fibrosis, the pathologist must be certain to evaluate both the quantity and thickness of the fibers. Reticulin fibers cannot be visualized in a hematoxylin & eosin (H&E) stained slide. Reticulin fibers are agyrophilic. This means that these tissue elements will stain black with a silver solution using the aid of a chemical reducer, which brings the silver into a visible form. This silver staining process is known as silver impregnation.
Texts that instruct on histologic techniques will provide several variations of the reticulin stain. Examples of reticulin stain using different methodologies are the Gordon & Sweets, Wilder, Gridley, Snook, Laidlaw, and Gomori. However, all methodologies have identical staining steps that prepare the reticulin fibers for staining.
The reticulin stain used to demonstrate reticulin fibers for this course is Gordon & Sweets.
