Sectioning bone: review of a special histology specimen

The significance of histological examination in the classification and diagnosis of clinical conditions relies on the expertise of the histology laboratory in managing the wide spectrum of specimen types submitted for analysis. From receipt of the tissue sample to presentation of a slide for microscopy examination, histologists must consider the composition of the specimen to determine how it should be handled. The majority of samples follow a routine cycle of dehydration and paraffin wax embedding in preparation for microtomy.

However, due to its high calcium content, bone is a particularly difficult tissue to section, with the density of a sample also being an important factor to consider in contributing to the risk of shattering. Cutting undecalcified bone sections requires resin embedding, specialised microtomy and modified staining techniques.

An iliac bone biopsy is procedurally very difficult to perform and uncomfortable for the patient, as it requires removal of a 4-mm core, which must include both bony plates of the iliac crest. As a consequence, most laboratories decalcify specimens, enabling them to be embedded in paraffin wax and processed as standard. Nitric acid and formic acid are used as decalcification agents, with the latter being more suitable for laboratories performing downstream molecular analysis because, unlike nitric acid, it does not destroy DNA.