| halo nevus | A benign, sometimes multiple, melanocytic nevus in which involution occurs with a central brown mole surrounded by a uniformly depigmented zone or halo. Synonym: leukoderma acquisitum centrifugum, Sutton's disease, Sutton's nevus. (05 Mar 2000) |
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| anaemic halo | Pale, relatively avascular areas in the skin seen around vascular spiders, cherry angiomas, and sometimes in acute macular eruptions. (05 Mar 2000) |
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| glaucomatous halo | A yellowish white ring surrounding the optic disk, indicating atrophy of the choroid in glaucoma. Synonym: glaucomatous ring. A halo surrounding lights, caused by corneal oedema in glaucoma. Synonym: rainbow symptom. (05 Mar 2000) |
| halo | <radiobiology> The cold, dense plasma formed outside the last closed flux surface during a vertical displacement event. The large currents which flow through this plasma stop the displacement and transfer the force to the vacuum vessel. If care is not taken in design, the halo currents can be large enough to threaten the structural integrity of the vacuum vessel or in-vessel components. Whereas the centre of a tokamak plasma is too hot for material probes to survive, probes (such as magnetic-field coils) can sometimes be placed in the halo, and can measure things such as the halo current. See: vertical instability. (09 Oct 1997) |
| halo blight | Halo blight is a fatal plant disease which attacks legumes and is caused by the bacteria Pseumonas phaseolicola. The plant develops yellow-ringed, water-soaked spots, then withers and dies without rotting. (09 Oct 1997) |
| halo cast | A cast applied to the shoulders in which metal bars are set that extend over the head to a halo, from which traction may be applied to the head by means of tongs or a halter. (05 Mar 2000) |
| halo current | <radiobiology> Currents in the halo region of a plasma discharge. See: halo. (09 Oct 1997) |
| halo effect | The effect (usually beneficial) that the manner, attention, and caring of a provider have on a patient during a medical encounter, regardless of what medical procedure or services the encounter involves, the influence upon an observation of the observer's perception of the characteristics of the individual observed (other than the characteristics under study) or the influence of the observer's recollection or knowledge of findings on a previous occasion. (05 Mar 2000) |
| halo melanoma | <tumour> A rare condition in which a melanoma is surrounded by an irregular area of depigmentation. (05 Mar 2000) |
| halo sign | <radiology> Narrow, radiolucent ring surrounding breast lesion, indicates benign tumour, rare exceptions: intracystic carcinoma, papillary carcinoma, carcinoma arising in fibroadenoma (12 Dec 1998) |
| halo sign of hydrops | A discredited roentgenographic sign of foetal hydrops caused by scalp oedema so that a definite corona surrounds the skull. (05 Mar 2000) |
| halo traction | Application of skeletal traction to the head by means of a halo device. (05 Mar 2000) |
| halo vision | A condition in which coloured or luminous rings are seen around lights. (05 Mar 2000) |
| senile halo | Circumpapillary halo seen in choroidal atrophy of the aged. (05 Mar 2000) |
| acquired nevus | A melanocytic nevus that is not visible at birth, but appears in childhood or adult life. (05 Mar 2000) |
| balloon cell nevus | A nevus in which many of the cells are large, with clear cytoplasm. (05 Mar 2000) |