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 edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

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2017 WHO histological classification of odontogenic and maxillofacial bone tumors

2017 WHO histological classification of odontogenic and maxillofacial bone tumors lays out a classification system for neoplasms and other tumors related to the odontogenic apparatus. Classification Malignant odontogenic tumors odontogenic carcinomas ameloblastic carcinoma primary intraosse...


Cerumen, also known as earwax, is a natural secretion produced by, and found within the external auditory canal (EAC). It has important roles as part of the first-line of defense of the ear from micro-organisms and optimizing function of the tympanic membrane and EAC. Secretion Cerumen is secr...

Charcot-Leyden crystals

Charcot-Leyden crystals consist of collections of bipyramidal crystalloid made up of eosinophilic membrane proteins, which occur in:  asthma other eosinophilic lung disease 2 certain cases of sinusitis (e.g. allergic fungal sinusitis) They may be detected in the sputum or sinus secretions wi...


A choristoma is simply a collection of microscopically normal cells or tissues in an abnormal location. This is different to a hamartoma which is derived only from local tissues. Examples include: adrenal choristoma (myelolipoma) nasopharyngeal choristoma facial nerve choristoma optic nerve...

Gene expression classifier

A gene expression classifier (GEC) test is a developing technology in the analysis of indeterminate thyroid nodules, using cells from a fine needle aspiration. The most common commercially available GEC in the United States is known as AFIRMA. The test is designed to use molecular markers to he...

Hernia (general)

Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening. The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...

Hurthle cell

Hurthle cells are a type of oncocyte arising from thyroid follicular epithelial cells. Pathology Under microscopy, Hurthle cells are larger than typical follicular cells, with abundant mitochondria. Cancers of Hurthle cell origin can be benign adenomas or malignant carcinomas and consist of a...


Iodine (chemical symbol I) is one of the trace elements. Its biological importance is its central place in the physiology of the thyroid gland and, in radiology, as the key chemical constituent of most of the radiographic, fluoroscopic, and CT contrast media. Chemistry Basic chemistry Iodine ...


The term lamellated (or laminated which means the same thing) is a radiopathological term used to describe the layered appearance of many calculi, including those of the renal tract, the salivary glands, and the biliary tree. The internal structure of these calculi has been likened to that of an...


p16 is a widely used immunohistochemical marker indicating expression of the cell cycle protein cyclin-dependent kinase inhibitor 2A, which is upregulated by human papillomavirus (HPV) infection. In the uterine cervix, p16 positivity supports the diagnosis of a high-grade squamous intraepithelia...

Psammoma bodies

Psammoma bodies are round microscopic calcific collections. It is a form of dystrophic calcification. Necrotic cells form the focus for surrounding calcific deposition. They have a lamellated concentric calcified structure, sometimes large enough to be seen on CT.  Psammoma bodies are found in ...

Senile calcific scleral plaques

Senile calcific scleral plaques, also known as senile scleral plaques, are benign scleral degenerations common in elderly individuals. They are a common incidental finding on CT imaging. Epidemiology The prevalence of senile scleral plaques increases with age, from ~2.5% at age 60, to 25% at a...


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 (...

WHO classification of eye tumors

The World Health Organization (WHO) classification of eye tumors is a widely used pathologic classification system of neoplasms of the orbit. The current revision, part of the 4th edition of the WHO series, was published in 2018 and is reflected in the article below 1. Classification Tumors of...

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