Indian Journal of Nuclear Medicine
Home | About IJNM | Search | Current Issue | Past Issues | Instructions | Ahead of Print | Online submissionLogin 
Indian Journal of Nuclear Medicine
  Editorial Board | Subscribe | Advertise | Contact
Users Online: 308 Print this page  Email this page Small font size Default font size Increase font size


 
 Table of Contents     
CASE REPORT
Year : 2019  |  Volume : 34  |  Issue : 1  |  Page : 51-53  

F-18 fluorodeoxyglucose positron emission tomography/computed tomography in the evaluation of intradiploic epidermoid cyst


Department of Nuclear Medicine, SVIMS, Tirupati, Andhra Pradesh, India

Date of Web Publication17-Jan-2019

Correspondence Address:
Dr. Tek Chand Kalawat
Department of Nuclear Medicine, SVIMS, Tirupati - 517 507, Andhra Pradesh
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijnm.IJNM_129_18

Rights and Permissions
   Abstract 


Epidermoid cysts are benign rare congenital cysts which typically present between 3rd and 5th decade of life. They mostly arise from cerebellopontine angle or parasellar region, but sporadic cases arise from cranial dipole. Here, we present a case of 42-year-old female with painful soft swelling in the left frontal region, which on F-18 fluorodeoxyglucose (FDG) positron emission tomography–computed tomography is well-circumscribed non-FDG avid lesion. The patient underwent total resection of the cyst, and the defect produced by space-occupying lesion was repaired by cranioplasty.

Keywords: Cranial dipole, epidermoid cyst, F-18 fluorodeoxyglucose positron emission tomography/computed tomography, frontal bone


How to cite this article:
Medara ST, Manthri RG, VS KM, Shaik M, Kalawat TC. F-18 fluorodeoxyglucose positron emission tomography/computed tomography in the evaluation of intradiploic epidermoid cyst. Indian J Nucl Med 2019;34:51-3

How to cite this URL:
Medara ST, Manthri RG, VS KM, Shaik M, Kalawat TC. F-18 fluorodeoxyglucose positron emission tomography/computed tomography in the evaluation of intradiploic epidermoid cyst. Indian J Nucl Med [serial online] 2019 [cited 2019 Feb 16];34:51-3. Available from: http://www.ijnm.in/text.asp?2019/34/1/51/250362




   Introduction Top


Most of the epidermoid cysts arise in cerebellopontine angle or parasellar region. The uncommon location of presentation of epidermoid cyst is dipole of the skull.[1] The overall estimated incidence of epidermoid cyst accounts to 0.2%–1.8% of intracranial tumors.[2] Intradiploic epidermoid cysts are considered to be the inclusion of wrongly placed ectodermal embryonic tissue in neural groove or its vicinity [2] or may occur after trauma which results in implantation of epidermal cells into the bones.[3]


   Case Report Top


A 42-year-old female presented with a single episode of unprovoked generalized tonic–clonic seizures. Review of her history revealed on and off episodes of a frontal headache over a duration of 4 months and painless swelling in the left frontal region for 6 months. On examination, the patient was conscious, coherent and denied any history of trauma, fever, gait instability, and visual disturbances. Neurological examination was normal.

Her history revealed benign meningioma 10 years ago, which was a well-circumscribed tumor and patient underwent left frontal craniotomy with complete resection of tumor followed by cranioplasty.

Whole-body F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) is done under the suspicion brain secondaries in a patient with a headache. Scan findings revealed non-FDG avid circumscribed hypodense lesion in the left frontal bone, measuring 2.3 cm × 3.0 cm. The lesion is causing the destruction of inner table of left frontal bone and extending intracranially with tumor to gray matter ratio (TGR) of 0.3, suggestive of intradiploic epidermoid [Figure 1] and [Figure 2].
Figure 1: (a-c) A nonfluorodeoxyglucose avid well-circumscribed hypodense lesion in the left frontal bone measuring 2.3 cm × 3.0 cm causing destruction of inner table of left frontal bone and extending intracranially. (a-c) represent axial computed tomography, positron emission tomography, and fused positron emission tomography/computed tomography images respectively

Click here to view
Figure 2: (d-f) Represent coronal computed tomography, positron emission tomography, and fused positron emission tomography/computed tomography images, respectively

Click here to view


Under general anesthesia, total excision of cyst was performed, and the defect formed by space-occupying lesion was repaired by cranioplasty. Histopathology of cystic lesion revealed areas of laminated keratin with no foci of calcification or hemorrhage, confirming benign epidermoid cyst [Figure 3]. Postoperative recovery was uneventful, and the patient was discharged on the 6th postoperative day.
Figure 3: Histopathology of the lesion showing areas of laminated keratin with no foci of calcification or hemorrhage, confirming benign epidermoid cyst

Click here to view



   Discussion Top


Epidermoid cysts are slow growing tumors. Most commonly, they are intradural in location [1] of which the most common site is cerebellopontine angle. They are ectodermal remnants, which during embryonic development remain within the skull bone [2] or they may also develop after iatrogenic trauma.[3],[4] The most common site of bony epidermoid cysts is calvarium, and other sites include paranasal sinuses, mandible, maxilla, temporomandibular joint, tibia, femur, and distal phalanges.[5] In skull, intradiploic space constitutes 25% of all epidermoid cysts and they commonly present as subcutaneous swelling,[6] sometimes associated with headache,[7] tenderness, and focal neurological signs. Rarely, they may cause seizures due to their enormous growth and may undergo malignant transformation.[7],[8]

Epidermoid cysts are lytic lesions with the rim of sclerotic bone and may erode into inner and outer tables of skull.[2],[3],[6],[9],[10] These cysts may rupture, bleed, and contents may spill into cerebrospinal fluid leading to aseptic meningitis.[11],[12] Cysts may spread along and compress surrounding structures resulting in facial and trigeminal palsy.[12]

Diagnosis is based on clinical examination followed by CT and magnetic resonance imaging (MRI) and histopathology. CT reveals size, extent of cyst,[7] and dural infiltration.[6] On MRI, cyst mostly shows heterogeneous signal intensity on T1-Weighted images and hyperintense on T2-weighted images [6] without any contrast enhancement. Intracranial extension of the cyst can be identified.

F-18 FDG PET/CT normally shows non-FDG avid hypodense lesion in intradiploic cyst. It can differentiate enhancing tumors such as gliomas, meningiomas, metastatic tumors, central nervous system lymphoma from nonenhancing tumors such as dermoids, any radiation necrosis,[13] based on FDG avidity and TGR. TGR is nearly 1.05 in enhancing tumors, 0.85 in recurrence and further less in dermoids and radiation necrosis.[14] However, confirmation of diagnosis is based on histopathological findings.

The differential diagnosis includes hydatid cyst, aneurysmal bone cyst, cavernous hemangioma, eosinophilic granuloma, and Langerhans histiocytosis.[15] After proper surgical excision, the recurrence rate of 8.3%–25% has been reported.[16]


   Conclusion Top


Intradiploic epidermoid cysts are rare. They can cause symptoms as they grow to a large size. Early evaluation including imaging followed by timely surgical resection is important to avoid potential complications. F-18 FDG PET/CT can be helpful in the differential diagnosis of intracranial lesions based on FDG avidity and tumor to gray matter ratio, thus improving the patient outcome.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Ulrich J. Intracranial epidermoids. A study on their distribution and spread. J Neurosurg 1964;21:1051-8.  Back to cited text no. 1
    
2.
Toglia JU, Netsky MG, Alexander E Jr. Epithelial (epidermoid) tumors of the cranium. Their common nature and pathogenesis. J Neurosurg 1965;23:384-93.  Back to cited text no. 2
    
3.
Rao BD, Subrahmanyam MV, Prabhakar V. Giant intra-diploic epidermoids. Neurol India 1968;16:93-8.  Back to cited text no. 3
    
4.
Pear BL. Epidermoid and dermoid sequestration cysts. Am J Roentgenol 1970;110:148-55.  Back to cited text no. 4
    
5.
Guiard JM, Kien P, Colombani S, Caillé JM. Intradiploic epidermoid cysts in adults. CT contribution to diagnosis in 6 new cases. J Neuroradiol 1986;13:22-31.  Back to cited text no. 5
    
6.
Arana E, Latorre FF, Revert A, Menor F, Riesgo P, Liaño F, et al. Intradiploic epidermoid cysts. Neuroradiology 1996;38:306-11.  Back to cited text no. 6
    
7.
Ciappetta P, Artico M, Salvati M, Raco A, Gagliardi FM. Intradiploic epidermoid cysts of the skull: Report of 10 cases and review of the literature. Acta Neurochir (Wien) 1990;102:33-7.  Back to cited text no. 7
    
8.
Kveton JF, Glasscock ME 3rd, Christiansen SG. Malignant degeneration of an epidermoid of the temporal bone. Otolaryngol Head Neck Surg 1986;94:633-6.  Back to cited text no. 8
    
9.
Skandalakis JE, Godwin JT, Mabon RF. Epidermoid cyst of the skull; report of four cases and review of the literature. Surgery 1958;43:990-1001.  Back to cited text no. 9
    
10.
Boyko OB, Scott JA, Muller J. Intradiploic epidermoid cyst of the skull: Case report. Neuroradiology 1994;36:226-7.  Back to cited text no. 10
    
11.
Nager GT. Epidermoids involving the temporal bone: Clinical, radiological and pathological aspects. Laryngoscope 1975;85:1-21.  Back to cited text no. 11
    
12.
White AK, Jenkins HA, Coker NJ. Intradiploic epidermoid cyst of the sphenoid wing. Arch Otolaryngol Head Neck Surg 1987;113:995-9.  Back to cited text no. 12
    
13.
Di Chiro G, Hatazawa J, Katz DA, Rizzoli HV, De Michele DJ. Glucose utilization by intracranial meningiomas as an index of tumor aggressivity and probability of recurrence: A PET study. Radiology 1987;164:521-6.  Back to cited text no. 13
    
14.
Cremerius U, Bares R, Weis J, Sabri O, Mull M, Schröder JM, et al. Fasting improves discrimination of grade 1 and atypical or malignant meningioma in FDG-PET. J Nucl Med 1997;38:26-30.  Back to cited text no. 14
    
15.
Smirniotopoulos JG, Chiechi MV. Teratomas, dermoids, and epidermoids of the head and neck. Radiographics 1995;15:1437-55.  Back to cited text no. 15
    
16.
Yanai Y, Tsuji R, Ohmori S, Tatara N, Kubota S, Nagashima C, et al. Malignant change in an intradiploic epidermoid: Report of a case and review of the literature. Neurosurgery 1985;16:252-6.  Back to cited text no. 16
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

Top
  
 
  Search
 
  
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
    Abstract
   Introduction
   Case Report
   Discussion
   Conclusion
    References
    Article Figures

 Article Access Statistics
    Viewed41    
    Printed0    
    Emailed0    
    PDF Downloaded11    
    Comments [Add]    

Recommend this journal