The group of so-called fibrohistiocytic tumors encompasses those tumors that were formerly believed to show evidence of hybrid fibroblastic and histiocytic differentiation. In truth, the neoplastic cells in these lesions likely represent either modified fibroblasts/myofibroblasts, or cells of histiocytic lineage,…
Introduction Tumors with myofibroblastic and fibroblastic differentiation comprise an ever-expanding and diverse group of largely spindle cell neoplasms. Some are characterized by recurrent gene fusions, resulting in chimeric transcription factors that initiate proliferative programs driving tumorigenesis and fibrous phenotype, while…
Immunohistochemistry Overview This section covers selected applications of immunohistochemistry (IHC) in the diagnosis of soft tissue and bone neoplasms, emphasizing the applications of IHC to the common differential diagnoses in soft tissue and bone pathology, including: (1) small, blue, round…
Sarcomas are a heterogeneous group of rare mesenchymal malignant tumors. These tumors can arise in all sites of the body and are classified by their line of differentiation according to the type of mature tissue they resemble, either muscle, fat,…
Introduction In order to provide the maximum degree of transparency to stained tissue sections, the refractive index of the mounting medium must approximate to that of dried protein, i.e. between 1.53 and 1.54. This is especially important for photographing slides.…
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Introduction The pH of a solution is defined as the logarithm to base 10 of 1 divided by the concentration of the free hydrogen ions in solution (i.e. pH = log 10 1/[A + ] = −log 10 [H +…
Introduction Most solutions in histology are made using water as a solvent. The agent dissolved in water to make an aqueous solution is the solute. Solutions typically are made as volume to volume or weight to volume. Concentrated formaldehyde is…
Introduction SI Units (Système International d’Unités, ) are used throughout this text. Under ISO 15189 ( ) there are two standards relating to measurement and measurement units (ISO 15189 standards F3.3 and F3.4). To attain ISO 15189 accreditation, laboratories must…
Introduction The histological diagnosis is often clear from light microscopic examination of tinctorial-stained slides. However, in cases with varying differential diagnoses, or where molecular subtleties will add to case interpretation, immunohistochemistry may be employed to reach a conclusion. In certain…