halo appearance

A generic term for a doughnut-shaped light density within and surrounded by rounded darker dense zones
Dermatology See Target lesions
Imaging, breast A rim of lower attenuation surrounding a benign well-circumscribed and radiodense fibroadenoma when seen by mammography
Imaging, CT See CT halo sign
Imaging, heart A halo of radiolucency seen on a plain AP chest film in pneumopericardium
Imaging, GI tract A ‘halo’ may be seen in duodenal ulcers, where the radiocontrast settles in a fixed location, typically in an ulcer within a mound of radiolucent edema surrounding the crater; alternatively, ‘halo’ refers to a saccular collection of radiocontrast surrounded by radiolucency, seen in the rare intraluminal duodenal diverticulum, causing a windsock deformity
Imaging, gynaecologic The ‘halo’ or wall sign is a smooth-contoured delineation of one tissue density from another, classically seen in a mature cystic teratoma or dermoid of the ovary on a plain abdominal film, or a contrast-enhanced CT, which is enhanced by the fibrous capsule investing the low-Hounsfield-unit mass which corresponds to keratinaceous debris, sebum and hair
Imaging, liver An avascular radiolucency surrounded by radiodensity, due to increased vascularity, seen by hepatic angiography in hemangiomas. CT, MRI and ultrasonography have reduced the utility of hepatic angiography to very specific applications; a ‘paradoxical’ halo may appear as an extrahepatic density, simulating an intrahepatic mass. Interestingly, a hypoechoic halo around a liver mass—by ultrasonography—should steer the diagnosis away from haemangioma
Imaging, obstretrics Spaulding’s halo sign A semispherical shadow seen on a plain film of the maternal abdomen, corresponding to the skull of a dead infant which is covered by edematous skin and soft tissue over the skull
Imaging, renal Hypernephroma halo A radiolucent rim surrounding perinephric fat caused by a diffuse renal mass, first described in renal cell carcinoma that may be seen in abscesses, haematomas, disseminated malignancy and, if left-sided, pancreatitis
Pathology, bone A rimming of osteocytic lacunae, seen by microscopy in X-linked hypophosphatemia due to delayed maturation
Pathology, breast An annular rim of stromal edema seen in gynaecomastia due to acid mucopolysaccharides—e.g., hyaluronic acid—which surrounds ducts with epithelial hyperplasia; a similar change is seen in fibroadenomas

halo appearance

adjective Referring to a doughnut-shaped light density within and surrounded by a rounded darker dense zones Bone pathology A rimming of osteocytic lacunae, seen by LM in X-linked hypophosphatemia, due to delayed maturation Cardiac imaging A halo of radiolucency seen on a plain AP chest film in pneumopericardium GI imaging The 'halo' may be seen either in duodenal ulcers, where the radiocontrast settles in a fixed location, typically occurring in an acute ulcer within a mound of radiolucent edema surrounding the crater; alternately, 'halo' refers to a saccular collection of radiocontrast surrounded by radiolucency, seen in the rare intraluminal duodenal diverticulum, causing a windsock deformity Gynecologic imaging The 'halo' or wall sign is a smooth-contoured delineation of one tissue density from another, seen in a mature cystic teratoma or dermoid on a plain abdominal film, enhanced by the fibrous capsule investing these benign tumors Hepatic imaging An avascular radiolucency surrounded by radiodensity, which corresponds to ↑ vascularity, seen by hepatic angiography in hemangiomas Obstetric imaging Spaulding's halo sign A semispherical shadow seen on a plain film of the maternal abdomen, corresponding to the skull of a dead infant that is covered by edematous skin and soft tissue over the skull Renal imaging Hypernephroma halo A radiolucent rim surrounding perinephric fat caused by a diffuse renal mass, first described in renal cell carcinoma or hypernephroma that may be seen in abscesses, hematomas, disseminated malignancy and pancreatitis.
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