Journal of Neurosciences in Rural Practice | July - December 2010 | Vol 1 | Issue 2 125

Frontal intraparenchymal “White epidermoid cyst”: A rare occurrence

Letters to the Editor

from C5 to D6 [Figures 2-7]. It was decided to continue conservative treatment with ATT and steroids. On it, the patient showed gradual improvement.

Tubercular meningitis (TBM) is the commonest chronic meningitis in India. Syringomyelia can rarely develop as an acute or chronic complication of TBM. The incidence of CNS TB is related to the prevalence of TB in the community, and it is still the most common type of chronic CNS infection in developing countries, like India. The incidence of intracranial tuberculomas as a complication of TBM varies between 1% and 28%.[1,2] The most frequent outcome in tuberculoma patients is the resolution of tuberculomas and complete clinical recovery within 12 weeks to 1 year with antitubercular therapy.[3] Many cases have been reported of patients developing tuberculomas post-TBM but the development of syringomyelia following TBM is very rare. TBM may rarely be followed by the development of a syrinx even aft er apparently successful chemotherapy. No medical treatment is known for patients with syringomyelia following TBM. However, a chronic, stable clinical course is common. Surgical treatment most likely will be necessary[4,5] though ideal treatment of syrinx following TBM is not known. However, our patient has been doing well on ATT without surgery. There has not been any progress of weakness and the condition of the patient remains stable. Thus, though rare acute or chronic syringomyelia can present as a complication of TBM or tuberculoma.

Santosh R Ramanathan, Tina AhluwaliaSenior Resident Max Superspecialty Hospital,

Saket, New Delhi-110017, India

Address for correspondence:Dr. Ramnath Santosh Ramanathan,10 Pragati Apts., Bhairavnath Road, Maninagar, Ahmedabad – 380 028,

Gujarat, India. E-mail: dr.santosh7@gmail. com

DOI: 10.4103/0976-3147.71734

References

1. Garcia-Monco JC. Central nervous system tuberculosis. Neurol Clin 1999;17:737-59.

2. Garg RK. Tuberculosis of the central nervous system. Postgrad Med J 1999;75:133-40.

3. Unal A, Sutlas PN. Clinical and radiological features of symptomatic central nervous system tuberculomas. Eur J Neurol 2005;12:797-804.

4. Sudo K, Miyazaki Y, Tajima Y, Matsumoto A, Tashiro K, Miyasaka K. Spontaneous resolution of idiopathic syringomyelia. Neurology 2002;58:1576-7.

5. Rusbridge C, Greitz D, Iskandar BJ. Syringomyelia: current concepts in pathogenesis, diagnosis, and treatment. J Vet Intern Med 2006;20:469-79.

Sir,Epidermoid cysts are benign, slow growing, extra-axial rare inclusion lesions accounting for approximately 0.5%–1.5% of all brain tumors. Cerebellopontine angle, petrous apex, suprasellar region, and the fourth ventricle are the usual locations. Only few cases of parenchymal epidermoid cysts have been reported.[1,2] Frontal lobe epidermoid cyst is extremely unusual.[2] They present with seizures. The symptoms of raised intracranial pressure are conspicuous by their absence. Although computed tomography (CT) scan usually shows a low-density area without contrast enhancement, abnormal CT fi ndings have been reported.[3] Magnetic resonance imaging (MRI) plays an important role in the diagnosis of intraparenchymal epidermoid cysts. They are usually hypointense on T1-weighted sequences and hyperintense on T2-weighted sequences. There may be unusual variation in MRI features..[3] Epidermoid cyst with hyperintensity on T1-weighted images is termed as white epidermoid.[4] We report a rare case of frontal intraparenchymal “white epidermoid cyst” managed at our institute.

A 39-year-old male was admitted with a history of repeated generalized tonic–clonic seizures for 8 months. Neurologic examination revealed no abnormality. CT scan brain showed a 3 × 2.5 × 2 cm, well-defi ned hypodense mass lesion not enhancing on contrast in the right frontal lobe without perilesional edema [Figure 1]. MRI study showed a similar size contrast nonenhancing lesion, which was hyperintense on T1-weighted images and hypointense on T2-weighted images [Figure 2a and b]. With these imaging fi ndings, a preoperative diagnosis of dermoid cyst vis-à-vis lipoma was considered. Complete removal of the lesion was carried out through a right frontal craniotomy. The cyst was yellowish, thin-walled, containing thick, dirty brown, grumous, oily material [Figure 3]. No hair or other dermal elements were observed. Histopathologic examination showed features of epidermoid cyst, namely, keratinizing squamous epithelium arranged in laminated layers with a thin layer of fi brous connective tissue [Figure 4].

MRI appearance depends on the chemical composition of the intracystic contents (cholesterol, keratin, and

Published online: 2019-09-25

126 Journal of Neurosciences in Rural Practice | July - December 2010 | Vol 1 | Issue 2

Figure 2: (a) MRI brain T1-weighted image (coronal view) showing hyperintense lesion in the right frontal lobe. (b) MRI brain T2-weighted image (axial view) showing hypointense lesion in the right frontal lobeFigure 3: Intraoperative photograph showing yellowish cystic lesion

Figure 4: Histopathologic section of the resected specimen showing lamellar keratin fl akes. (H and E stain)

Letters to the Editor

Figure 1: CT brain (axial view) showing a hypodense lesion in the right frontal lobe

calcium). The hypointensity on T1-weighted images is due to cholesterol in crystalline form or from calcium. On T2-weighted images, the commonly seen hyperintensity is due to keratin. These lesions usually do not show enhancement on administration of contrast. However, occasionally, they may show mild enhancement, however, exact mechanism of the same is not clear. Abnormal MRI fi ndings include heterogenous appearance on T1- and T2- weighted images.[5] Rarely, these lesions are hyperintense on T1-weighted images and hypointense on T2-weighted images, as in this case. This is because of the higher protein content in the cyst. Horowitz studied fi ve patients having epidermoid cyst and described hyperintensity on T1-weighted images. He felt that this was because of high lipid concentration comprising mixed triglycerides and unsaturated fatt y acid residues.[6] No details were reported regarding T2-weighted images.

Since fat (cholesterol) is an irritant for the pachymeninges, care should be taken during excision of these lesions. Due

Journal of Neurosciences in Rural Practice | July - December 2010 | Vol 1 | Issue 2 127

Real-time intraoperative ultrasonography in the surgical resection of brain lesions: A cheap, eff ective, and quick alternative

Sir,Neuronavigational systems are becoming more and more available in neurosurgical operation theaters and have become a standard form of accessories in the operating room for surgical resection of brain and spinal cord lesions.[1] Many intraoperative guiding systems have been developed, including intraoperative

magnetic resonance imaging (MRI; Brain suit) for this purpose,[2,3] however, these instruments are quite expensive. Therefore, the need for intraoperative real-time imaging has becomes more important, although it may not be that effi cient but it can partially overcome the problem of the cost. Apart from this it is cheap, portable, and accurate and may be more useful while working with limited resources.[1] Five consecutive brain tumor cases in supratentorial region as well as in infratentorial region were operated and a real-time neuronavigation system was used by senior author in the near past [Figure 1]. Multiple images were taken at the start of operations, during the procedures, and at the end of the procedure. At the end, the extent of tumor excision was assessed and if there was any tumor left , further excision was performed keeping in mind “safe resection.” Postoperative CT or MRI images were performed and compared with the extent shown in intraoperative ultrasonography (USG) to correlate the extent of tumor excision and reliability vis-a-vis CT or MRI imaging. It was found that the real-time intraoperative USG helped us to guide the extent of tumor and extent of excision or decompression of the tumors and correlated quite well as inferred with the postoperative CT or MRI imaging.

The intraoperative USG images may be as good as if not superior to good quality MRI images.[4,5] The intraoperative USG imaging may easily be performed through the same opening as used for resection of tumor. [1] Most neurosurgeons are familiar with the MRI images than the USG because they interpret MRI images every day in clinical practice, but Neurosurgeons who have started using USG and want to explore the possibilities

Letters to the Editor

to the cystic nature of the lesion, greater care should be taken to ensure that the cyst does not rupture thereby leading to chemical meningitis. For the same reason, needle aspiration should be avoided and every att empt should be made to excise the cyst completely.

Batuk Diyora, Naren Nayak, Dhananjay Kale, Hanmant Kamble, Alok Sharma

Department of Neurosurgery, L.T.M.G. Hospital, Sion (W), Mumbai – 400 022, India

Address for correspondence:Dr. Batuk Diyora,

Department of Neurosurgery, 2nd Floor, L.T.M.G. Hospital, Sion (W), Mumbai – 400 022, India.

E-mail: bddiyora@hotmail.com

DOI: 10.4103/0976-3147.71735

References

1. Kumari R, Guglani B, Gupta N, Chaturvedi S. Intracranial epidermoid cyst: Magnetic resonance imaging features. Neurol India 2009;57:359-60.

2. Hamada Y, Kishi H, Matsuo S. Intraparenchymal epidermoid cyst of the right frontal lobe: A case report. No Shinkei Geka 1985;13:695-9.

3. Gualdi GF, Di Biasi C, Trasimeni G, Pingi A, Vignati A, Maira G. Unusual MR and CT appearance of an epidermoid tumor. AJNR Am J Neuroradiol 1991;12:771-2.

4. Wagle WA, Jaufmann B, Mincy JE. Magnetic resonance imaging of the Fourth ventricular epidermoid tumors. Arch Neurol 1991;48:438-40.

5. Vion-Dury J, Vincentelli F, Jiddane M, Van Bunnen Y, Rumeau C, Grisoli F, et al. MR imaging of epidermoid cysts. Neuroradiology 1987;29:333-8.

6. Horowitz BL, Chari MV, James R, Bryan RN. MR of intracranial epidermoid tumors. AJNR Am J Neuroradiol 1990;11:299-302.

Figure 1: Intraoperative pre-excision images (a and b), intraoperative postexcision images (c and d)