Lipoma of the cerebellopontine angle Case report

MASASHI FUKUI, M.D., AKIRA TANAKA, M.D., KATSUTOSHI KITAMURA, M.D., AND TOSHIO OKUDERA, M.D.

Department of Neurosurgery, Neurological Institute, and Department of Radiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan The authors present a surgical case of a lipoma of the cerebellopontine angle in a 28-year-old woman. KFV WORDS

9 lipoma

9 cerebellopontine angle

I

NTRACRANIALlipoma is a rare tumor occuring most commonly in the midsagittal region. 2,' Except for those in the callosal area, reported eases were almost exclusively asymptomatic and were usually incidentally found at autopsy. 1,4,10 Reports of lipoma of the cerebellopontine angle treated surgically are extremely rare; 1 we are presenting such a case. Case Report

A 28-year-old woman had had occasional bifrontal region headache for about 10 years. Not until March, 1973, did she note hearing difficulty accompanied by a feeling of obstruction and tinnitus in the left ear. At the same time she felt a peculiar sensation of numbness around the left ear that gradually subsided in several months. In December, 1973, she suddenly felt giddy upon standing up, and when she immediately lay down, she felt a typical vertigo. The tinnitus, hearing difficulty, and feeling of obstruction of the left ear persisted and she was admitted on February 15, 1974. Examination. The patient was slightly obese but otherwise unremarkable on 544

9 surgical removal

physical examination. Neurological examination revealed only loss of hearing of the left ear, later identified as of mixed type. Caloric response of the ear was normal. Plain skull x-ray films revealed a sharply demarcated defect of the left petrous pyramid (Fig. 1). The margin of the defect was rather osteosclerotic. Tomograms revealed a bone defect involving the left jugular foramen, jugular tuberculum, and internal auditory meatus. A brain scan was negative. Vertebral angiography by transfemoral catheter technique revealed no displacement of the vessels in the posterior fossa except for the left petrosal vein which was equivocally displaced laterally. The peripheral portion of the left anterior inferior cerebellar artery, however, was abnormally dilated and more tortuous than usual (Fig. 2). No tumor stain was noted. Left carotid angiography revealed no abnormality. Fractional pneumoencephalography demonstrated an obliteration of the left cerebellopontine cistern. Cerebrospinal fluid (CSF) pressure was as high as the level of the foramen magnum with the patient in the sitting position. The CSF contained 2 lymphocytes/cu mm and 26.5 mg/100 ml of protein.

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Lipoma of the cerebellopontine angle Operation. A left suboccipital craniectorny was performed on March 12, 1974. A yellowish, soft, grossly globular tumor was found, thinly encapsulated, in the left cerebellopontine angle, occupying the concave defect of the left petrous bone. The tumor was firmly attached to the arachnoid membrane of the left cerebellar hemisphere and the brain stem, but not to the dura of the petrous bone. The left 7th, 8th, 9th, and 10th cranial nerves were embedded in the tumor, while the left 5th and 12th cranial nerves were slightly displaced. A large tortuous vessel ran from the inferior pole of the tumor upward along the posterior border. The tumor was partially removed intracapsularly, preserving the embedded cranial nerves. The postoperative course was uneventful, and the patient was discharged 15 days postoperatively. At present, 2 years after operation, she is doing well, but the hearing loss of the left ear remains unchanged. Histological Examination. The tumor was composed of mature adipose tissue containing a small number of abnormally thick

FIG. 1. Plain skull film showing a large, sharply outlined defect of the left petrous pyramid (arrows). The margin of the defect is osteosclerotic.

arteries, engorged veins, and capillaries. No other hamartomatous elements were found in the tumor. The histological diagnosis was lipoma (Fig. 3).

FIG. 2. Vertebral angiograms, anteroposterior (left), and lateral (right), showing abnormal dilatation and tortuosity of the left anterior inferior cerebellar artery at the cerebellopontine angle (arrows).

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M. Fukui, A. Tanaka, K. Kitamura and T. Okudera

FIG. 3. Histological section of the tumor showing mature adipose tissue and an abnormally thick artery. The tumor was diagnosed histologically as lipoma (angiolipoma). H & E, • 110.

Discussion

In cases o f intracranial lipoma, symptoms of a space-occupying lesion were reported to be very rare. TM Epileptic attacks and mental problems were reported in many cases but were regarded as the results of co-existing central nervous system dysgenesis? Budka ~ also stressed the paucity of focal symptoms in intracranial lipomatous hamartoma (intracranial lipoma); among 4290 neurosurgical biopsies the lesion was found only once, while 12 other cases were found at autopsy (four of which were in a series of 1560 routine autopsies). It is thus considered extremely rare to encounter an intracranial lipoma at surgery, especially at sites other than the corpus callosum. As far as we know, the case of Budka a is the only other case of lipoma of the cerebellopontine angle found at surgery. In that case, slowly progressing local symptoms, such as trigeminal neuralgia, vertigo with nausea, vomiting, nystagmus, and deafness, were 546

present. As accompanying lesions, a dermoid cyst of the ovary, a fibroadenoma of the breast, and an incomplete lumbosacral spina bifida were noted. In our case the symptoms were occasional headache, hearing difficulty, tinnitus, feeling of obstruction of the ear, and episodic vertigo. The disturbance of the 8th cranial nerve and the sharply outlined defect of the ipsilateral petrous pyramid in x-ray films suggested a mass lesion in the cerebellopontine angle, but acoustic neurinoma was less likely because of normal caloric response of the ear and normal content of C S F protein. Absence of tumor stain in angiograms tended to rule out meningioma, metastatic tumor, hemang i o b l a s t o m a , glomus jugulare t u m o r , and ceruminous tumor, sa A benign extra-axial tumor probably of congenital origin was our preoperative diagnosis. In cases of callosal lipoma, dilatation, tortuosity, and irregularity of the pericallosal artery were reported as the angiographic characteristics) The angiographic findings of the anterior inferior cerebellar artery in our case are similar to those of the pericallosal artery in callosal lipoma. As in the case of Budka, 1 the t u m o r in our patient could not be totally removed because many cranial nerves and large vessels were incorporated in it. A similar condition was well demonstrated in an autopsy reported by Krainer.' These tumors are usually not true neoplasms but of maldevelopmental origin?,+,e,lo References

1. Budka H: Intracranial lipomatous hamartomas (intracranial "lipomas"): a study of 13 cases including combinations with medulloblastoma, colloid and epidermoid cysts, angiomatosis and other malformations. Acta Neuropathol 28:205-222, 1974 2. Demus H: Neue Gesichtspunkte zur Entstehung der pialen Lipome. Ein Beitrag zur Klinik, Pathologie, Entstehungsweise und Herkunft der Fettgeschwtllste des Zentralnervensystems. Arch Psyehiatr Nervenkr 209:426-442, 1967 3. Henschen F: Tumoren des Zentralnervensystems und seiner Hiillen, in Lubarsch O, Henke F, Rossle R (eds): Handbuch der speziellen pathologischen Anatomie und Histologie, Band 3. Berlin/G~ttingen/Heidelberg: Springer-Verlag, 1955, pp 413-1040 J. Neurosurg. / Volume 46 / April, 1977

Lipoma of the cerebellopontine angle 4. Krainer L: Die Hirn- und Rflckenmarkslipome. Virchows Arch Pathol Anat 295: 107-142, 1935 5. Norman D, Newton TH: Ceruminous tumors of the cerebeliopontine angle. Neuroradiology 10:1-4, 1975 6. Russell DS, Rubinstein L J: Tumours of the Nervous System, ed 2. London: Edward Arnold, 1971, pp 25-26 7. Takahashi M, Okudera T, Tomanaga M, et al: Angiographic diagnosis of acoustic neurinomas: analysis of 30 lesions. Neuroradiology 2:191-200, 1971 8. Wolpert SM, Carter BL, Ferris E J: Lipomas of the corpus callosum: an angiographic analysis. Am J Roentgenol Radium Ther Nucl Med 115:92-99, 1972

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9. Zettner A, Netsky MG: Lipoma of the corpus callosum. J Neuropathol Exp Neurol 19: 305-319, 1960 10. Ztilch K J: Biologie und Pathologie der Hirngeschwtllste, in Olivecrona H, TSnnis W (eds): Haodbueh tier Neurochirurgie III. Berlin: Springer-Verlag, 1956, pp 496-500 Address for Dr. Tanaka: Department of Neurosurgery, Faculty of Medicine, Fukuoka University, Fukuoka 814, Japan. Address for Dr. Okudera: Research Institute of Brain and Blood Vessels, Akita, Akita 010, Japan. Address reprint requests to: Masashi Fukui, M.D., Department of Neurosurgery, Neurological Institute, Faculty of Medicine, Kyushu University, Fukuoka 812, Japan.

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Lipoma of the cerebellopontine angle. Case report.

Lipoma of the cerebellopontine angle Case report MASASHI FUKUI, M.D., AKIRA TANAKA, M.D., KATSUTOSHI KITAMURA, M.D., AND TOSHIO OKUDERA, M.D. Depart...
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