J Neurosurg 48:1035-1037, 1978
Preoperative diagnosis of a ruptured intracranial dermoid cyst by computerized tomography Case report MARCO A. AMENDOLA,M.D., WILLIAM B. GARFINKLE,M.D., BERNARD J. OSTRUM, M.D., M. RICHARD KATZ, M . D . , AND RICHARD I. KATZ, M.D. Radiology Department, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, Departments of Neurology and Radiology, Temple University School of Medicine, and DiviSions of Neurologic Surgery, Neurology, and Radiology, Albert Einstein Medical Center, Philadelphia, Pennsylvania w' A case of ruptured intracranial dermoid cyst in the right middle fossa is reported. A definitive diagnosis of the lesion and the fact that it had ruptured was made possible by specific computerized tomographic findings. The findings were confirmed at surgery. KEY WORDS 9 computerized tomography intracranial dermoid cyst
I
NTRACRANIAL dermoid cysts have been diagnosed preoperatively with greater frequency since the advent of computerized tomography (CT). The characteristic CT appearance of fat gives presumptive evidence of the histology of the lesion. We are reporting a case of a ruptured intracranial dermoid cyst diagnosed preoperatively by CT. A unique feature of this case is that the fatty contents of the tumor spilled into the subarachnoid space with no extension into the ventricular system. Case Report
This 26-year-old right-handed salesman was seen in December, 1976, for evaluation of headaches and seizures. J. Neurosurg. / Volume 48 / June. 1978
9 preoperative diagnosis
9
The patient had an episode of generalized seizures 31/2 years before his present admission. After a negative work-up including radioisotope brain scan and electroencephalography (EEG), he was placed on Dilantin (phenytoin sodium) therapy. Eighteen months later he discontinued the Dilantin and was well until 2 weeks before admission, when he had another generalized seizure. In November, 1976, he had complained of daily bouts of bifrontal, non-throbbing headaches, which were usually worse in the morning. The rest of the history and physical examination were unremarkable. Examination. Cranial CT, performed in December, 1976, as an outpatient procedure, showed a large mass lesion in the right middle cranial fossa. Absorption values within the 1035
M. A. Amendola, et al.
FIG. 1. Computerized tomography section showing a low-absorption mass circumscribed by a calcification in the right temporal fossa. Readings beneath cursor indicate 55 Hounsfield units, that is, fat density.
FIG. 2. Coronal CT section showing the subtemporal location of the lesion. Note the calcific rim around the mass. ]036
Fie;. 3. Computerized tomography section showing fat-density lesions in the right Sylvian fissure and over the cerebral convexity.
mass were in the range of - 2 0 to - 6 0 Hounsfield units suggesting fat density (Fig. 1). A curvilinear rim of high absorption consistent with calcification partially circumscribed the lesion (Fig. 1). Computerized tomographic sections obtained in the coronal plane showed that the mass was subtemporal in location (Fig. 2). In addition, multiple small lesions, again with density measurements in the fat range, were scattered over the convexity of the brain and in the right Sylvian fissure (Fig. 3). N o enhancement was noted in the lesions in sections obtained after the intravenous injection of 100 cc of Renografin 60. The ventricular system was not enlarged and there was no shift of midline structures. No fat or fat-fluid levels were present in the ventricles. Findings were interpreted as a subtemporal dermoid cyst with rupture into the subarachnoid space. Ancillary studies included skull x-ray films and right brachial arteriogram. The skull films showed a calcified rim in the right middle fossa. The arteriogram demonstrated an avascular subtemporal extra-axial mass lesion. Operation. At surgery, yellowish cheesy material was found along the right Sylvian fissure. This material was traced to a capsule J. Neurosurg. / Volume 48 / June, 1978
CT diagnosis of ruptured intracranial dermoid cyst surrounding a mass that arose from the floor of the middle fossa and extended upward and posteriorly, compressing the tip of the temporal lobe. A tiny opening in the capsule of the cyst directly c o m m u n i c a t e d with the Sylvian fissure, which had a r a t h e r thick arachnoid m e m b r a n e . A d h e s i o n s to the medial surface of the t e m p o r a l lobe were noted. On histological e x a m i n a t i o n , the interrupted cyst wall was seen to be lined by stratified squamous epithelium. Within the underlying collagenous tissue, skin appendages consisting of hair follicles and m a n y sebaceous glands could be recognized. Postoperative Course. The patient had an uncomplicated postoperative course with full recovery. H e has had no further seizure activity. Discussion
Plain skull x-ray visualization of an intracerebral dermoid cyst as a radiolucent mass has been a rare occurrence. Only two cases have been r e p o r t e d " since it was first described by Gross in 1945) Recent a t t e n t i o n has been called by Maravilla s to the presence in horizontal-beam skull x-ray studies of an intraventricular fatfluid level secondary to the rupture of an intracranial dermoid cyst. Fat-fluid levels may be diagnosed by CT as in the case described by Cornell, et al. 1 In their case, the radiolucent area was at first thought to represent air until the absorption values at C T indicated the presence of fat. Diagnosis of fat-containing dermoid and epidermoid t u m o r s by C T scanning has been reported in several instances. 2-4 In 1977, Laster, et al., 7 reported for the first time the preoperative diagnosis of two intracranial dermoid t u m o r s that ruptured into the subarachnoid space. This diagnosis was made possible because of the typical C T appearance of fat globules free in the subarachnoid space along with fat-fluid levels in the lateral ventricles, plus the cystic-appearing tumor. In the present case the dermoid cyst ruptured only into the subarachnoid space and no intraventricular fat could be demonstrated at C T or at surgery. It is of interest to note that the rapidly fatal consequences of the escape of dermoid cyst contents into the cerebrospinai pathway anticipated by Russell and Rubinstein 1~ and J. Neurosurg. / Volume 48 / June, 1978
reported by Krieg 6 and Olivecrona 9 have not been observed in Laster's cases nor in ours. Notwithstanding, a chronic g r a n u l o m a t o u s arachnoiditis was certainly present in our case. The most irritant element is considered to be the cholesterol derived f r o m the breakdown of keratin. References
1. Cornell SH, Graf C J, Dolan KD: Fat-fluid level in intracranial epidermoid cyst. Am J Roentgenol 128:502-503, 1977 2. Davis KR, Roberson GH, Taveras JM, et al: Diagnosis of epidermoid tumor by computed tomography. Analysis and evaluation of findings. Radiology 119:347-353, 1976 3. Fawcett RA, Isherwood I: Radiodiagnosis of intracranial pearly tumours with particular reference to the value of computer tomography. Neuroradiology 11:235-242, 1976 4. Gawler J, Du Boulay GHD, Bull JWD, et al: Computer-assisted tomography (EMI scanner). Its place in investigation of suspected intracranial tumours. Lancet 2:4t9-422, 1974 5. Gross SW: Radiographic visualization of an intracerebral dermoid cyst. J Neurosurg 2:72-75, 1945 6. Krieg W: Aseptische meningitis nach Operation von Cholesteatomen des Gehirns. Zentralbl Neurochir 1:79-86, 1936 7. Laster DW, Dixon DM, Ball MR: Epidermoid tumors with intraventricular and subarachnoid fat: report of two cases. Am J Roentgenol 128:504-507, 1977 8. Maravilla KR: lntraventricular fat-fluid level secondary to rupture of an intracranial dermold cyst. Am J Roentgenol 128:500-501, 1977 9. Olivecrona H: On suprasellar cholesteatomas. Brain 55:122-134, 1932
10. Russell DS, Rubinstein LJ: Pathology of Tumors of the Nervous System, ed 3.
Baltimore: Williams and Wilkins, 1971, p 18 11. Zylak C J, Childe AE, Ross RT, et al: Lucent unilateral supratentorial dermoid cyst. Report of an unusual case. Am J Roentgenol Radium Ther Nucl Med 106:329-332, 1969
Address for Dr. Amendola: Radiology Department, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia. Address reprint requests to: William B. Gartinkle, M.D., Division of Radiology, Albert Einstein Medical Center, York and Tabor Roads, Philadelphia, Pennsylvania 19141. 1037
Preoperative diagnosis of a ruptured intracranial dermoid cyst by computerized tomography Case report MARCO A. AMENDOLA,M.D., WILLIAM B. GARFINKLE,M.D., BERNARD J. OSTRUM, M.D., M. RICHARD KATZ, M . D . , AND RICHARD I. KATZ, M.D. Radiology Department, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, Departments of Neurology and Radiology, Temple University School of Medicine, and DiviSions of Neurologic Surgery, Neurology, and Radiology, Albert Einstein Medical Center, Philadelphia, Pennsylvania w' A case of ruptured intracranial dermoid cyst in the right middle fossa is reported. A definitive diagnosis of the lesion and the fact that it had ruptured was made possible by specific computerized tomographic findings. The findings were confirmed at surgery. KEY WORDS 9 computerized tomography intracranial dermoid cyst
I
NTRACRANIAL dermoid cysts have been diagnosed preoperatively with greater frequency since the advent of computerized tomography (CT). The characteristic CT appearance of fat gives presumptive evidence of the histology of the lesion. We are reporting a case of a ruptured intracranial dermoid cyst diagnosed preoperatively by CT. A unique feature of this case is that the fatty contents of the tumor spilled into the subarachnoid space with no extension into the ventricular system. Case Report
This 26-year-old right-handed salesman was seen in December, 1976, for evaluation of headaches and seizures. J. Neurosurg. / Volume 48 / June. 1978
9 preoperative diagnosis
9
The patient had an episode of generalized seizures 31/2 years before his present admission. After a negative work-up including radioisotope brain scan and electroencephalography (EEG), he was placed on Dilantin (phenytoin sodium) therapy. Eighteen months later he discontinued the Dilantin and was well until 2 weeks before admission, when he had another generalized seizure. In November, 1976, he had complained of daily bouts of bifrontal, non-throbbing headaches, which were usually worse in the morning. The rest of the history and physical examination were unremarkable. Examination. Cranial CT, performed in December, 1976, as an outpatient procedure, showed a large mass lesion in the right middle cranial fossa. Absorption values within the 1035
M. A. Amendola, et al.
FIG. 1. Computerized tomography section showing a low-absorption mass circumscribed by a calcification in the right temporal fossa. Readings beneath cursor indicate 55 Hounsfield units, that is, fat density.
FIG. 2. Coronal CT section showing the subtemporal location of the lesion. Note the calcific rim around the mass. ]036
Fie;. 3. Computerized tomography section showing fat-density lesions in the right Sylvian fissure and over the cerebral convexity.
mass were in the range of - 2 0 to - 6 0 Hounsfield units suggesting fat density (Fig. 1). A curvilinear rim of high absorption consistent with calcification partially circumscribed the lesion (Fig. 1). Computerized tomographic sections obtained in the coronal plane showed that the mass was subtemporal in location (Fig. 2). In addition, multiple small lesions, again with density measurements in the fat range, were scattered over the convexity of the brain and in the right Sylvian fissure (Fig. 3). N o enhancement was noted in the lesions in sections obtained after the intravenous injection of 100 cc of Renografin 60. The ventricular system was not enlarged and there was no shift of midline structures. No fat or fat-fluid levels were present in the ventricles. Findings were interpreted as a subtemporal dermoid cyst with rupture into the subarachnoid space. Ancillary studies included skull x-ray films and right brachial arteriogram. The skull films showed a calcified rim in the right middle fossa. The arteriogram demonstrated an avascular subtemporal extra-axial mass lesion. Operation. At surgery, yellowish cheesy material was found along the right Sylvian fissure. This material was traced to a capsule J. Neurosurg. / Volume 48 / June, 1978
CT diagnosis of ruptured intracranial dermoid cyst surrounding a mass that arose from the floor of the middle fossa and extended upward and posteriorly, compressing the tip of the temporal lobe. A tiny opening in the capsule of the cyst directly c o m m u n i c a t e d with the Sylvian fissure, which had a r a t h e r thick arachnoid m e m b r a n e . A d h e s i o n s to the medial surface of the t e m p o r a l lobe were noted. On histological e x a m i n a t i o n , the interrupted cyst wall was seen to be lined by stratified squamous epithelium. Within the underlying collagenous tissue, skin appendages consisting of hair follicles and m a n y sebaceous glands could be recognized. Postoperative Course. The patient had an uncomplicated postoperative course with full recovery. H e has had no further seizure activity. Discussion
Plain skull x-ray visualization of an intracerebral dermoid cyst as a radiolucent mass has been a rare occurrence. Only two cases have been r e p o r t e d " since it was first described by Gross in 1945) Recent a t t e n t i o n has been called by Maravilla s to the presence in horizontal-beam skull x-ray studies of an intraventricular fatfluid level secondary to the rupture of an intracranial dermoid cyst. Fat-fluid levels may be diagnosed by CT as in the case described by Cornell, et al. 1 In their case, the radiolucent area was at first thought to represent air until the absorption values at C T indicated the presence of fat. Diagnosis of fat-containing dermoid and epidermoid t u m o r s by C T scanning has been reported in several instances. 2-4 In 1977, Laster, et al., 7 reported for the first time the preoperative diagnosis of two intracranial dermoid t u m o r s that ruptured into the subarachnoid space. This diagnosis was made possible because of the typical C T appearance of fat globules free in the subarachnoid space along with fat-fluid levels in the lateral ventricles, plus the cystic-appearing tumor. In the present case the dermoid cyst ruptured only into the subarachnoid space and no intraventricular fat could be demonstrated at C T or at surgery. It is of interest to note that the rapidly fatal consequences of the escape of dermoid cyst contents into the cerebrospinai pathway anticipated by Russell and Rubinstein 1~ and J. Neurosurg. / Volume 48 / June, 1978
reported by Krieg 6 and Olivecrona 9 have not been observed in Laster's cases nor in ours. Notwithstanding, a chronic g r a n u l o m a t o u s arachnoiditis was certainly present in our case. The most irritant element is considered to be the cholesterol derived f r o m the breakdown of keratin. References
1. Cornell SH, Graf C J, Dolan KD: Fat-fluid level in intracranial epidermoid cyst. Am J Roentgenol 128:502-503, 1977 2. Davis KR, Roberson GH, Taveras JM, et al: Diagnosis of epidermoid tumor by computed tomography. Analysis and evaluation of findings. Radiology 119:347-353, 1976 3. Fawcett RA, Isherwood I: Radiodiagnosis of intracranial pearly tumours with particular reference to the value of computer tomography. Neuroradiology 11:235-242, 1976 4. Gawler J, Du Boulay GHD, Bull JWD, et al: Computer-assisted tomography (EMI scanner). Its place in investigation of suspected intracranial tumours. Lancet 2:4t9-422, 1974 5. Gross SW: Radiographic visualization of an intracerebral dermoid cyst. J Neurosurg 2:72-75, 1945 6. Krieg W: Aseptische meningitis nach Operation von Cholesteatomen des Gehirns. Zentralbl Neurochir 1:79-86, 1936 7. Laster DW, Dixon DM, Ball MR: Epidermoid tumors with intraventricular and subarachnoid fat: report of two cases. Am J Roentgenol 128:504-507, 1977 8. Maravilla KR: lntraventricular fat-fluid level secondary to rupture of an intracranial dermold cyst. Am J Roentgenol 128:500-501, 1977 9. Olivecrona H: On suprasellar cholesteatomas. Brain 55:122-134, 1932
10. Russell DS, Rubinstein LJ: Pathology of Tumors of the Nervous System, ed 3.
Baltimore: Williams and Wilkins, 1971, p 18 11. Zylak C J, Childe AE, Ross RT, et al: Lucent unilateral supratentorial dermoid cyst. Report of an unusual case. Am J Roentgenol Radium Ther Nucl Med 106:329-332, 1969
Address for Dr. Amendola: Radiology Department, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia. Address reprint requests to: William B. Gartinkle, M.D., Division of Radiology, Albert Einstein Medical Center, York and Tabor Roads, Philadelphia, Pennsylvania 19141. 1037
