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Neuroradiology Case of the Week
Case 419
June 2009
Derek Lasher, Ashwani K. Sharma, MD and
P-L Westesson, MD, PhD, DDS
Clinical
Presentation: Patient is a 65-year-old female who presented with an asymptomatic left neck mass.
Imaging Findings: On MR imaging, T1-weighted images show a homogeneous, hyperintense lesion that does not enhance with contrast agent. On fat-saturated images, signal loss is expected. T2-weighted images are expected to follow the fat signal.
CT findings for NECT include a well-defined, homogeneous, low attenuated mass with a fat density expected at -65 to -120 Hounsfield units (HU).
Ultrasonographic findings expected are as follows: A compressible, well-defined mass, elliptical in shape with the long axes oriented parallel to the skin, with 75% being hyperechoic, and 25% being isoechoic relative to the muscle.
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| Figures 1A-D: Axial post-contrast CT of the lower neck reveals mass in the left supraclavicular region. CT density is -110 HU. The mass is insinuating in the intermuscular planes. There are septa in the mass. No solid nodular component noted. No abnormal enhancement is noted in the mass.
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Diagnosis: Lipoma
Discussion: Lipomas are slow-growing, benign neoplasms made up entirely of fat, and are the most common variety of soft tissue tumor. They are found in approximately 1% of the population, with higher frequency in males. They are liable to occur anywhere on the body, though 15% are found in the head/neck region. Multiple occurrences are found in 5% of cases.
Lipomas are characterized by their homogeneity of mature fat cells that are well encapsulated by a thin, fibrous membrane. They generally lack any notable internal structure, though 8% of benign lipomas have a small, non-fatty soft tissue element. Patients generally present without any symptoms other than the mass itself, though overly large specimens have a tendency to displace surrounding structures, which could lead to associated symptoms. Differential diagnoses for lipomas include: dermoid tumor, craniofacial teratoma, lymphangioma, and liposarcoma. Lipomas do not generally require treatment, though surgical debulking may be performed for cosmetic reasons, or to reduce the compression of surrounding structures.
Upon MR imaging, T1-weighted images show a homogeneous, hyperintense lesion that does not enhance with contrast agent. On fat-saturated images, signal loss is expected. T2-weighted images are expected to follow the fat signal. CT findings for NECT include a well-defined, homogeneous, low attenuated mass with a fat density expected at -65 to -120 HU. Ultrasonographic findings expected are as follows: A compressible, well-defined mass, elliptical in shape with the long axes oriented parallel to the skin, with 75% being hyperechoic, and 25% being isoechoic relative to the muscle.
Prognosis for benign lipomas is excellent, with a low rate of recurrence.This is, however, possible if it is not entirely removed upon resection.
References:
- Nickloes TA, Sutphin DD, Radeboid K. Lipomas. eMedicine, January 15, 2009. http://emedicine.medscape.com/article/191233-overview.
- Harnsberger HR, Hudgins PA, Wiggins RW III, et al. Diagnostic Imaging: Head and Neck. Amirsys, 2004, pgs IV-2-6 to IV-2-9.
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