Articles
Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
More than 200 results
Article
Malignant transformation
Malignant transformation is the term given to the process whereby either normal, metaplastic, or benign neoplastic tissue, becomes a cancer. The process usually occurs in a series of steps and the affected tissue gradually accumulates the genetic mutations that express a malignant phenotype. The...
Article
Neoplasm
Neoplasms, also known as tumors, are pathological masses, caused by cells abnormally proliferating and/or not appropriately dying. Neoplasms may be either benign or malignant. Malignant neoplasms are synonymous with cancers.
Benign neoplasms
clear origin (unless very large)
slow growth
usua...
Article
Sessile
Sessile is a pathological term which is used for lesions that are attached by their base, that is they lack a stalk i.e. are not pedunculated. It is most commonly used for intraluminal polyps in the GI tract.
History and etymology
Sessile is derived from the Latin word "sessilis" which means s...
Article
Ballistics (overview)
Ballistics is the scientific study of projectiles. Numerous variables determine initial projectile velocity, characteristics of flight, and the projectile's effects on the target. These can be divided into the fields of internal ballistics, external ballistics, and terminal ballistics. Understan...
Article
Glial fibrillary acid protein (GFAP)
Glial fibrillary acid protein (GFAP) is a commonly used target for immunohistochemistry and is positive in many glial cells and tumors of glial origin. GFAP is the building block for intermediate filaments which are abundant in the cytoplasms particularly of astrocytes.
Related pathology
Alex...
Article
Klebsiella
Klebsiella is a genus of Gram-negative, oxidase-negative, rod-shaped bacteria, which is relatively commonly encountered in the healthcare environment. It has numerous species, including K. pneumoniae, K. aerogenes, and K. rhinoscleromatis 1. Klebsiella may cause a range of infections, most commo...
Article
Transcriptome
The transcriptome refers to the set of all transcribed RNA, including the messenger RNA (mRNA), which is eventually is translated into proteins, as well as non-coding RNA molecules (e.g. transfer RNA (tRNA), ribosomal RNAs (rRNA), microRNA, etc.).
Unlike the genome, which is fixed (barring spo...
Article
Perivascular pseudorosettes (ependymoma)
Perivascular pseudorosettes are a common histologic feature of central nervous system ependymomas. They represent sections through papillary structures composed of tumor cells arranged radially around a central vessel. Between the central vessel and the tumor cells is a relatively microscopicall...
Article
Phlegmon
Phlegmon (plural: phlegmons) refers to soft connective tissue inflammation, usually in the context of infectious disease. It is distinct from an abscess, which is a collection of pus walled-off by granulation tissue.
Terminology and Usage
Historically and contemporaneously, phlegmon is used in...
Article
Arias-Stella reaction
An Arias-Stella reaction is a common gynecological histological finding in curettage specimens of gestational endometrium describing a non-neoplastic lesion that is easily confused with uterine malignancy 1,2.
Pathology
An Arias-Stella reaction is due to hormonal hyperstimulation causing atypi...
Article
Gliosis
Gliosis is a reactive process occurring after some time following most types of central nervous system injuries and is the result of focal proliferation of glial cells, particularly astrocytes.
Terminology
Although the terms astrocytic gliosis or astrocytosis are often used interchangeably wi...
Article
Thyroseq
Thyroseq® is an expanded gene classifier test designed for further evaluation of indeterminate thyroid nodules on fine needle aspiration (FNA). In particular, it is designed to further evaluate nodules that show atypia of undetermined significance/follicular lesion of undetermined significance (...
Article
Endochondral ossification
Endochondral ossification is one of the two key methods of bone formation (the other being intramembranous ossification). Endochondral ossification occurs in ossification centers within a cartilaginous mold (anlagen) of a bone, progressively replacing that mold with bone 4. After primary ossific...
Article
Mesenchyme
Mesenchyme, or mesenchymal connective tissue, is a type of undifferentiated connective tissue. It is predominantly derived from the embryonic mesoderm, although may be derived from other germ layers, e.g. mesenchyme derived from neural crest cells (ectoderm).
The term mesenchyme is often used t...
Article
Prostatic acid phosphatase
Prostatic acid phosphatase (PAP) also known as prostatic specific acid phosphatase (PSAP) is an enzyme generated by prostatic glandular tissue.
Usage
It can be used in immunohistochemistry to identify prostatic tissue including prostatic epithelium and prostatic ducts and is usually expressed ...
Article
Glycosaminoglycans
Glycosaminoglycans (GAGs), formerly known as mucopolysaccharides, are biomolecules produced by almost all mammalian cells, as well as in many vertebrates and invertebrates, but have not been described in plants 1. They are constituent elements of proteoglycans and are found within the cells in t...
Article
CA 19-9
CA 19-9 (carbohydrate antigen 19-9 or cancer antigen 19-9) is a serum antigen (monosialoganglioside) that has increased diagnostic use in the management of several malignancies, mainly of hepatopancreaticobiliary origin. It is non-specific, however, and can rise in both malignant and non-maligna...
Article
CSF alpha-fetoprotein
Alpha-fetoprotein (AFP) in the cerebrospinal spinal fluid (CSF) has been reported as a tumor marker for some intracranial tumors with yolk sac elements, and teratoma 1.
Interpretation
Elevation
intracranial yolk sac tumor
intracranial embryonal carcinoma
congenital CNS tumors with yolk sac ...
Article
CDKN2A/p16
CDKN2A (cyclin-dependent kinase inhibitor 2A) is a tumor suppressor gene that encodes for the p16 protein, involved in the CDK4/6–RB1 cell-cycle pathway 5.
p16 is a widely used immunohistochemical marker indicating expression of the cell cycle protein, which is upregulated by human papillomavi...
Article
John Cunningham virus
John Cunningham virus, also known as human polyomavirus 2, universally known as the JC virus, is a ubiquitous double-stranded DNA virus of the polyomaviridae family 1. In immunocompromised individuals, reactivation can lead to a variety of disease of the central nervous system, the most common o...
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