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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 8  |  Issue : 2  |  Page : 41-43

“Face mask sign” on Tc-99m methylene diphosphonate bone scan


Department of Nuclear Medicine and PET-CT, Kamalnayan Bajaj Hospital, Aurangabad, Maharashtra, India

Date of Submission28-Jul-2020
Date of Decision28-Aug-2020
Date of Acceptance28-Aug-2020
Date of Web Publication5-Oct-2020

Correspondence Address:
Prathamesh Vijay Joshi
Department of Nuclear Medicine and PET.CT, Kamalnayan Bajaj Hospital, Beed Bypass Road, Aurangabad . 431 010, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jomr.jomr_16_20

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  Abstract 


Although bone scan is a sensitive imaging modality, it is nonspecific, and there are multiple potential causes of abnormal isotope uptake that can mimic metastatic disease. A 67-year-old male, a known case of prostate carcinoma, underwent bone scan for skeletal evaluation. His prostate biopsy had revealed adenocarcinoma of the prostate. His serum prostate-specific antigen level was 11.8 ng/ml. The scan showed increased tracer uptake in bilateral maxillary sinuses mimicking shape of the face mask. To characterize the abnormal tracer uptake in the bilateral maxillary sinuses and rule out the metastatic lesion, single-photon emission computed tomography–computed tomography (SPECT-CT) correlation was obtained. The SPECT-CT revealed mucosal thickening obliterating sinus space in the bilateral maxillary sinuses, suggesting the uptake secondary to maxillary sinusitis. On questioning, the patient admitted of having chronic history of pain along the sides of the nose and yellowish nasal mucus discharge. We concluded the uptake to be result of the bilateral maxillary sinusitis. We propose that such uptake pattern can be designated as 'face mask sign' on bone scan.

Keywords: Bone scan, prostate carcinoma, chronic sinusitis, face mask sign, maxillary sinusitis, single-photon emission computed tomography–computed tomography


How to cite this article:
Joshi PV, Kulkarni M, Kumar K. “Face mask sign” on Tc-99m methylene diphosphonate bone scan. J Oral Maxillofac Radiol 2020;8:41-3

How to cite this URL:
Joshi PV, Kulkarni M, Kumar K. “Face mask sign” on Tc-99m methylene diphosphonate bone scan. J Oral Maxillofac Radiol [serial online] 2020 [cited 2020 Nov 28];8:41-3. Available from: https://www.joomr.org/text.asp?2020/8/2/41/297220




  Introduction Top


Bone scan is frequently used for evaluation of suspected or known skeletal metastases in patients with malignancy. However not all lesions seen on bone scan are neoplastic/ metastatic and sometimes benign pathologies also can be incidentally detected on bone scan. We describe an interesting pattern seen on bone scan of a prostate carcinoma patient, which lead to diagnosis of maxillary sinusitis.


  Case Report Top


A 67-year-old male, a known case of prostate carcinoma, underwent bone scan for skeletal evaluation. His prostate biopsy had revealed adenocarcinoma of the prostate with Gleason's score 4 + 4 = 8. His serum prostate-specific antigen level was 11.8 ng/ml. His previous surgical history included laminectomy of C4 to C6 and L3 to L5 vertebrae, 2 years ago for spinal stenosis. The bone scan was performed on GE NM 630 dual-head gamma camera, 3 h after intravenous injection of 740 MBq of Tc-99m methylene diphosphonate (MDP). The whole body bone scan [Figure 1]a and [Figure 1]b showed increased tracer uptake in the cervical and lumbar vertebrae, which corresponded to postoperative vertebrae and degenerative changes seen on single-photon emission computed tomography–computed tomography (SPECT-CT) (not shown in images). Abnormal increased tracer uptake was seen in the bilateral maxillary sinuses mimicking shape of face mask [Figure 1]c.
Figure 1: A 67-year-old male, a known case of prostate carcinoma, underwent bone scan for skeletal evaluation. The whole body bone scan (a and b) showed increased tracer uptake in the cervical and lumbarvertebrae which corresponded to postoperative vertebrae. (c) In addition to these findings, abnormal increased tracer uptake was seen in the bilateral maxillary sinuses mimicking shape of face mask

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To characterize the abnormal tracer uptake in the bilateral maxillary sinuses and rule out the metastatic lesion, SPECT-CT correlation was obtained. The SPECT-CT [Figure 2]a - CT, [Figure 2]b - SPECT, and [Figure 2]c - SPECT-CT fusion] revealed mucosal thickening obliterating sinus space in the bilateral maxillary sinuses, suggesting the uptake secondary to maxillary sinusitis. On questioning, the patient admitted of having chronic history of pain along the sides of the nose and yellowish nasal mucus discharge. We concluded the uptake to be result of chronic maxillary sinusitis.
Figure 2: To characterize the abnormal tracer uptake in the bilateral maxillary sinuses and rule out the metastatic lesion, SPECT- CT correlation was obtained. The SPECT-CT ([a] CT, [b] SPECT, and [c] SPECT-CT fusion) revealed mucosal thickening obliterating sinus space in the bilateral maxillary sinuses suggesting the uptake secondary to maxillary sinusitis. SPECT: Single-photon emission computed tomography, CT: Computed tomography

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  Discussion Top


Bone scintigraphy is frequently performed as part of the routine staging of patients with a wide variety of primary malignancies. Although it is a sensitive imaging modality, it is relatively nonspecific, and there are many potential causes of increased isotope uptake that can mimic metastatic disease.[1] Sinusitis is a known cause of abnormal Tc-99 m MDP uptake in nasal sinuses and it needs to be distinguished from metastatic disease involving skull.[2] SPECT/CT is reported to be potentially useful for this site to obviate additional skull radiographs or CT.[3] In previous study, it had been shown that marked accumulation of Tc-99m MDP indicates inflammatory metabolic changes of the sinus bony walls, predicting a severe clinical course and the necessity of aggressive treatment.[4] In our case, the Tc-99m MDP uptake in the bilateral maxillary sinuses was incidentally seen and it resulted in an uptake pattern mimicking “face mask.” Further correlation with SPECT-CT and clinical history lead to diagnosis of maxillary sinusitis.


  Conclusion Top


We present intriguing uptake of Tc-99m MDP in the bilateral maxillary sinuses as a result of sinusitis and we propose that such uptake pattern can be designated as 'face mask sign' on bone scan.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Moran DE, O'Neill AC, Heffernan EJ, Skehan SJ. Not everything that is hot on a staging bone scan is malignant: A pictorial review of benign causes of increased isotope uptake. Can Assoc Radiol J 2012;63:280-8.  Back to cited text no. 1
    
2.
Wale DJ, Wong KK, Savas H, Kandathil A, Piert M, Brown RK. Extraosseous findings on bone scintigraphy using fusion SPECT/CT and correlative imaging. AJR Am J Roentgenol 2015;205:160-72.  Back to cited text no. 2
    
3.
Gnanasegaran G, Cook G, Adamson K, Fogelman I. Patterns, variants, artifacts, and pitfalls in conventional radionuclide bone imaging and SPECT/CT. Semin Nucl Med 2009;39:380-95.  Back to cited text no. 3
    
4.
Ostfeld E, Aviel A, Pelet D. Bone scintigraphic diagnosis in acute frontal sinusitis. Acta Otolaryngol1982:94;557-61.  Back to cited text no. 4
    


    Figures

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