“…The signal intensity of vascular structures within the tumors may reflect high flow (low signal intensity on all MR images regardless of pulse sequences) or low flow (high signal intensity on T2-weighted images). The tumors enhance after the administration of intravenous gadolinium-based contrast material and may demonstrate central areas of necrosis (4,77).…”
Section: Soft Tissue Angiosarcomamentioning
confidence: 99%
“…Although most soft tissue tumors occur in the trunk and extremities, the head and neck also are frequently involved. In fact, head and neck sarcomas represent an estimated 15% of sarcomas in adults and 35% of sarcomas in children (1)(2)(3)(4)(5)(6).…”
Section: Introductionmentioning
confidence: 99%
“…Arrowheads = flow voids. appearance, with regions of hemorrhage, necrosis, and cystic change(4,63,65).…”
The World Health Organization (WHO) system for defining and classifying soft tissue tumors is usually applied to lesions that occur in the trunk and extremities, but it also provides an excellent framework for characterizing nonepithelial extraskeletal tumors of the head and neck. Although nonepithelial extraskeletal tumors are in the minority among head and neck lesions, they are by no means rare. The WHO classification system recognizes nine major types based on histologic differentiation: adipocytic, fibroblastic or myofibroblastic, fibrohistiocytic, smooth muscle, skeletal muscle, vascular, pericytic, and chondro-osseous tumors, as well as soft tissue tumors of uncertain differentiation. Tumors of each histologic type may be further subclassified on the basis of their biologic behavior as benign, intermediate (ie, having malignant potential), or malignant. Imaging plays an important role in the noninvasive diagnosis and characterization of nonepithelial soft tissue tumors of the head and neck, providing clues about tumor grade, composition, extent, and involvement of adjacent structures. Although the imaging characteristics of many such tumors are nonspecific, consideration of the clinical history in concert with the imaging findings may help limit the differential diagnosis or even allow reliable diagnosis of some of these tumors.
“…The signal intensity of vascular structures within the tumors may reflect high flow (low signal intensity on all MR images regardless of pulse sequences) or low flow (high signal intensity on T2-weighted images). The tumors enhance after the administration of intravenous gadolinium-based contrast material and may demonstrate central areas of necrosis (4,77).…”
Section: Soft Tissue Angiosarcomamentioning
confidence: 99%
“…Although most soft tissue tumors occur in the trunk and extremities, the head and neck also are frequently involved. In fact, head and neck sarcomas represent an estimated 15% of sarcomas in adults and 35% of sarcomas in children (1)(2)(3)(4)(5)(6).…”
Section: Introductionmentioning
confidence: 99%
“…Arrowheads = flow voids. appearance, with regions of hemorrhage, necrosis, and cystic change(4,63,65).…”
The World Health Organization (WHO) system for defining and classifying soft tissue tumors is usually applied to lesions that occur in the trunk and extremities, but it also provides an excellent framework for characterizing nonepithelial extraskeletal tumors of the head and neck. Although nonepithelial extraskeletal tumors are in the minority among head and neck lesions, they are by no means rare. The WHO classification system recognizes nine major types based on histologic differentiation: adipocytic, fibroblastic or myofibroblastic, fibrohistiocytic, smooth muscle, skeletal muscle, vascular, pericytic, and chondro-osseous tumors, as well as soft tissue tumors of uncertain differentiation. Tumors of each histologic type may be further subclassified on the basis of their biologic behavior as benign, intermediate (ie, having malignant potential), or malignant. Imaging plays an important role in the noninvasive diagnosis and characterization of nonepithelial soft tissue tumors of the head and neck, providing clues about tumor grade, composition, extent, and involvement of adjacent structures. Although the imaging characteristics of many such tumors are nonspecific, consideration of the clinical history in concert with the imaging findings may help limit the differential diagnosis or even allow reliable diagnosis of some of these tumors.
“…Since the large tumor may make capsule very thin and closely cling to the adjacent normal tissue, and therefore indiscernible on MR images. Malignancies may grow pushing against adjacent structures and form a pseudocapsule as they enlarge [18,24]. The pseudocapsule consists of compressed fibrous connective tissue, normal tissue, vascularization, and inflammatory reaction [24].…”
“…Myxoid liposarcomas (Fig. 16) can appear cystic and can have elevated T2 signal intensity in non-lipomatous elements, with a tendency for reticular enhancement [60]. Ultrasound can be useful in myxoid subtypes, as sonography can demonstrate that the mass is not truly cystic, and further investigation with biopsy may be warranted.Fig.…”
The perinephric space, shaped as an inverted cone, sits between the anterior and posterior renal fasciae. It can play host to a variety of clinical conditions encountered daily in the reporting schedule for a radiologist. Lesions may be classified and diagnosed based on their imaging characteristics, location and distribution. A broad range of differential diagnoses can be attributed to pathology sitting within this space, often without clinical signs or symptoms. An understanding of commonly encountered conditions affecting the perinephric space, along with characteristic imaging findings, can illustrate and often narrow the likely diagnosis. The aim of this essay is to describe commonly encountered neoplastic and non-neoplastic entities involving the perinephric space and to describe their key imaging characteristics.Teaching Point• Despite often a bulky disease, perinephric lymphoma does not produce obstruction or stenosis.• In primarily fatty masses, defects within the renal capsule likely represent angiomyolipoma.• Consider paraganglioma if biopsy is planned; biopsy may lead to catecholamine crisis.
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