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Journal ArticleDOI

Pathogenesis of intracranial lipoma: an MR study in 42 patients.

01 Oct 1990-American Journal of Roentgenology (AJR Am J Roentgenol)-Vol. 155, Iss: 4, pp 855-864
TL;DR: The relative frequencies of the locations of the lipomas correspond to the temporal sequence of dissolution of the meninx primitiva, the mesenchymal anlage of the Meninges, and this finding supports the concept of lipoma formation as a result of abnormal persistence and maldifferentiation of theMeninx.
Abstract: Intracranial lipomas are uncommon lesions whose development remains poorly understood. To clarify the anatomic and embryologic features of intracranial lipomas, we retrospectively reviewed the MR scans of 42 patients with 44 intracranial lipomas. Interhemispheric lipomas were the most common, accounting for 45% of cases. The remainder of the lesions were clustered in the quadrigeminal/superior cerebellar (25%), suprasellar/interpeduncular (14%), cerebellopontine angle (9%), and sylvian (5%) cisterns. Fifty-five percent of the lesions were associated with brain malformations of varying degrees. Intracranial vessels and nerves were noted to course through 16 (36%) of the lesions. The relative frequencies of the locations of the lipomas correspond to the temporal sequence of dissolution of the meninx primitiva, the mesenchymal anlage of the meninges. This finding supports the concept of lipoma formation as a result of abnormal persistence and maldifferentiation of the meninx. This embryologic concept of the development of intracranial lipomas explains the high frequency of callosal and other brain hypoplasias. Intracranial lipomas are neither hamartomas nor true neoplasms; rather, they are congenital malformations.
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Journal ArticleDOI
TL;DR: The chemical shift phenomenon refers to the signal intensity alterations seen in magnetic resonance (MR) imaging that result from the inherent differences in the resonant frequencies of precessing protons.
Abstract: The chemical shift phenomenon refers to the signal intensity alterations seen in magnetic resonance (MR) imaging that result from the inherent differences in the resonant frequencies of precessing protons. Chemical shift was first recognized as a misregistration artifact of image data. More recently, however, chemical shift has been recognized as a useful diagnostic tool. By exploiting inherent differences in resonant frequencies of lipid and water, fatty elements within tissue can be confirmed with dedicated chemical shift MR pulse sequences. Alternatively, the recognition of chemical shift on images obtained with standard MR pulse sequences may corroborate the diagnosis of lesions with substantial fatty elements. Chemical shift can aid in the diagnosis of lipid-containing lesions of the brain (lipoma, dermoid, and teratoma) or the body (adrenal adenoma, focal fat within the liver, and angiomyolipoma). In addition, chemical shift can be implemented to accentuate visceral margins (e.g., kidney and liver).

160 citations

Journal Article
TL;DR: It is suggested that the mesenchyme formed by the prechordal plate, notochord, and neural crest play an important part in the early development of the brain and that anomalies of the meschyme underlie this disorder as well as other forms of holoprosencephaly.
Abstract: PURPOSE To describe the imaging features of a brain anomaly found on studies of three patients, and to speculate on the embryologic basis leading to the development of this abnormality. PATIENTS AND METHODS Clinical records (three patients), MR scans (two patients), and CT scans (two patients) of three patients with fusion of the middle portions of the cerebral hemispheres in the presence of nearly normal anterior interhemispheric fissures were retrospectively reviewed. The results were correlated with the present theories of brain development in an attempt to classify the anomaly and define the underlying embryologic abnormalities. RESULTS All three patients with middle interhemispheric fusion were severely developmentally delayed. Associated anomalies were identified in all three and included neuronal migration anomalies, callosal dysgenesis, and hypoplasia of the anterior falx cerebri. Correlation of the imaging findings with theories of brain development lead to the suggestion that this anomaly is the result of deficient or dysplastic mesenchyme, which leads to disordered brain development. CONCLUSION Middle interhemispheric fusion may be considered as a variant of holoprosencephaly. It is suggested that the mesenchyme formed by the prechordal plate, notochord, and neural crest play an important part in the early development of the brain and that anomalies of the mesenchyme underlie this disorder as well as other forms of holoprosencephaly.

144 citations

Journal ArticleDOI
TL;DR: In cases in which diagnostically specific T1-weighted imaging features are lacking, findings obtained with other MR pulse sequences and other modalities can help narrow the differential diagnosis: An elevated glutamine or glutamate level at MR spectroscopy is suggestive of hepatic encephalopathy; a popcorn ball-like appearance at T2- Weighted imaging, of cavernous malformations; and hyperattenuation at computed tomography, of mineral deposition disease.
Abstract: Knowledge about the physical properties of substances that produce high signal intensity at T1- weighted MR imaging provides a solid foundation for the differential diagnosis of intracranial lesions with a bright appearance on T1-weighted images.

128 citations

Journal Article
TL;DR: Neurocutaneous melanosis appears to involve the brain in specific locations that can be detected on MR imaging, and knowledge of these locations can aid in differentiating metastases, secondary to malignant degeneration of the large cutaneous nevi, from melanotic deposits that are a part of the disease.
Abstract: PURPOSE To describe the MR findings of neurocutaneous melanosis in the brain and correlate these with the known pathology and proposed embryologic basis of this disorder. METHODS The brain (seven patients) and spine (three patients) MR scans of seven patients with neurocutaneous melanosis were retrospectively reviewed. In two patients, findings were confirmed at surgery. The pattern of central nervous system involvement was also correlated with known pathologic studies regarding frequency and location of melanotic deposits. RESULTS Five patients had regions of T1 shortening in the cerebellum; three of these also had T2 shortening. Five patients had regions of T1 shortening in the anterior temporal lobes. Other areas of involvement included the pia mater over the cerebellum (two patients), pons (one patient), medulla (one patient), and left parietal lobe (one patient). Only two lesions showed enhancement, edema, or necrosis; both were proved malignant melanomas at biopsy. No pial enhancement was detected. CONCLUSION Neurocutaneous melanosis appears to involve the brain in specific locations that can be detected on MR imaging. Knowledge of these locations can aid in differentiating metastases, secondary to malignant degeneration of the large cutaneous nevi, from melanotic deposits that are a part of the disease. Identification of malignant degeneration of the melanotic deposits is difficult; at present, it depends on the identification of growth, edema, or necrosis of the deposits.

122 citations

Journal ArticleDOI
TL;DR: With the magnetic resonance imaging techniques now available, lipomas can be reliably differentiated from other masses within the CPA and IAC, so histopathologic diagnosis is rarely necessary, and conservative follow‐up is the best treatment option for patients with these rare lesions.
Abstract: Objective: To evaluate lipomas of the internal auditory canal (IAC) and cerebellopontine angle (CPA). Study Design: Retrospective review. Methods: Review of a multi-institutional series of 17 lipomas of the IAC/CPA, combined with a Medline review of the 67 cases reported in the world literature. Results: This series of 17 IAC/CPA lipomas is the largest reported series to date, bringing the total number of documented cases to 84. There appears to be a nearly 2:1 male to female predominance. Sixty percent were leftsided lesions, and three were bilateral. Hearing loss, dizziness, and tinnitus were the most common presenting symptoms. Surgical resection was performed in 52 (62%) of these lesions; however, total tumor removal was accomplished in only 17 (33%), which is most likely because of the fact that these tumors tend to have a poorly defined matrix and a dense adherence to neurovascular structures. Sixty-eight percent of patients experienced a new deficit postoperatively, 11% were unchanged, and only 19% improved with no new deficit. Only one documented case of tumor growth was identified; however, the reported follow-up was short (average, less than 3 years). Conclusion: With the magnetic resonance imaging techniques now available, lipomas can be reliably differentiated from other masses within the CPA and IAC, so histopathologic diagnosis is rarely necessary. Because of the potential for significant morbidity with resection of these lesions, we believe that conservative follow-up is the best treatment option for patients with these rare lesions. Surgery is indicated only when significant progressive or disabling symptoms are present. Laryngoscope, 108:1459–1469, 1998

67 citations


Cites background from "Pathogenesis of intracranial lipoma..."

  • ...Cases With Reported Symptoms n (%) Hearing loss 49 (64) Dizziness 34 (44) Tinnitus 33 (43) Headache 12 (16) Trigeminal symptoms 10 (13) Facial nerve symptoms 6 (8) Ear pain 5 (6) Asymptomatic 4 (5) Seizures 3 (4) Cutaneous nevi 3 (4) Visual symptoms 2 (3) Gait disturbance 2 (3) Dysphagia 1 (1) Hoarseness 1 (1) Ptosis 1 (1) Proptosis 1 (1) Lower body parasthesias 1 (1) Arm dyskinesia 1 (1) Total 77 Fig....

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