|Year : 2022 | Volume
| Issue : 3 | Page : 295-299
MRI Evaluation of Salivary Gland Involvement by Buccal Squamous Cell Carcinoma
Department of Oral Medicine and Radiology, S P Dental College and Hospital, DMIMSDU, Sawangi-M, Wardha, Maharastra, India
|Date of Submission||23-Apr-2022|
|Date of Decision||11-Aug-2022|
|Date of Acceptance||12-Aug-2022|
|Date of Web Publication||26-Sep-2022|
Department of Oral Medicine and Radiology, S P Dental College and Hospital, DMIMSDU, Sawangi-M, Wardha (Maharastra) - 442 001
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: The salivary gland involvement by oral squamous cell carcinoma (OSCC) and diagnostic delays may influence the recurrence and survival of OSCC cases. Aims and Objective: To estimate salivary gland involvement in buccal OSCC cases. Materials and Methods: For 91 histopathologically proven cases of buccal OSCC, the primary tumor and salivary gland were evaluated using magnetic resonance imaging (MRI) sequences as T1-T2-weighted, diffusion-weighted, short tau inversion recovery, and contrast-enhanced images. Results: Out of 91 buccal OSCC patients, 10 (10.98%) cases showed salivary gland involvement, primarily the ipsilateral submandibular gland involvement with heterogeneous enhancement and few areas of necrosis. Conclusion: The considerable proportion of buccal OSCC cases with salivary gland involvement as evaluated in MRI was demonstrated in the present study. The study findings underscore the need for careful pre-treatment evaluations toward salivary gland involvement, especially in occult cases.
Keywords: Buccal mucosa, magnetic resonance imaging, oral cancer, salivary glands
|How to cite this article:|
Panchbhai A. MRI Evaluation of Salivary Gland Involvement by Buccal Squamous Cell Carcinoma. J Indian Acad Oral Med Radiol 2022;34:295-9
|How to cite this URL:|
Panchbhai A. MRI Evaluation of Salivary Gland Involvement by Buccal Squamous Cell Carcinoma. J Indian Acad Oral Med Radiol [serial online] 2022 [cited 2022 Dec 10];34:295-9. Available from: http://www.jiaomr.in/text.asp?2022/34/3/295/356949
| Introduction|| |
Oral squamous cell carcinoma (OSCC) is aggressive in nature, grows rapidly, and penetrates well with a high recurrence rate. Being soft tissue malignancy, the squamous cell carcinoma (SCC) of buccal mucosa (buccal OSCC), is considered as most aggressive and prevalent oral cancer in the range 14.2 to 63.3%.,,,,,
A high incidence of loco-regional failure and recurrence are observed in the case of buccal OSCC; the inadequate treatment and intrinsically aggressive nature may be the possible reasons behind it. Owing to its aggressive nature, there may be a likely possibility of involvement of salivary glands and glandular lymph nodes in addition to anatomic structures in the immediate vicinity.,,,,
Magnetic resonance imaging (MRI) is the most advantageous modality for anatomical detail and soft tissue characterization. The extent of invasion, lymphadenopathy, and occult metastasis can be evaluated better using MRI compared to other advanced imaging modalities.,,,,,,
Clinical examination and tumour, node and metastases (TNM) staging cannot evaluate the depth of invasion and metastasis, especially occult. Besides, histopathological evaluation can be done only on the excised tissue specimen. Hence, the role of imaging may be crucial in a comprehensive evaluation of the region of interest proved as the excellent soft tissue discrimination through its various image sequences to provide complete evaluation of tumor and structures in its vicinity for metastatic involvement.,,,,,
The present work aimed to assess the parotid and submandibular gland involvement by buccal OSCC through MRI evaluation.
| Materials and Methods|| |
The present cross-sectional study was conducted in a dental hospital in India for which the prior scrutiny and ethics committee approval was obtained (Institutional ethics committee, DMIMSDU/Ethic/18-19/7785, 21.12.18).
At the outset, voluntary written consent obtained study sample was included using convenient sampling, taking 95% of the confidence interval. The 91 histopathologically proven cases of buccal OSCC were included in the study. The metastasis was ruled on the basis of long-term case history through clinical evaluation and co-existence of any other malignancy in the patient.
For each study participants, thorough clinical examination, TNM staging,, and histopathological evaluation were done. The MRI evaluation (GE Brivo355) was done using various sequences as T1-weighted, T2-weighted, diffusion-weighted, contrast, and short tau inversion recovery (STIR).
MRI protocol for images to be obtained (GE Brivo355, 1.5 Tesla)
- frFSE: l/160
- FOV: 28 X 28
- WW 1433, WL 716
- TR 4997, TE 110
Sample size calculation
Z value = 1.96, level of significance at 5%, i.e., 95% confidence interval P = prevalence (31.47%), = 0.3147
d = desired margin of error (7%), = 0.07
SS = 86.26
The images in 3 planes, axial, coronal, and sagittal, were evaluated in all MRI sequences using criteria as margins, extent, and signal intensity of lesion, and the involvement of salivary glands by buccal OSCC [Figure 1].
|Figure 1: Buccal OSCC of the right side (a) involving the right parotid gland (b) (Axial section, T2 weighted)|
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The observations were tabulated for analysis. For this cross-sectional study, the frequency distribution and percentage of each variable derived and the descriptive statistics was applied using Chi-square test using SPSS Software Company.
| Results|| |
The age-wise and gender-wise distribution of 91 buccal OSCC is shown in [Table 1].
Observations about buccal OSCC with salivary gland involvement
In 10 buccal OSCC patients (10.98%) that showed salivary gland involvement, two cases involved parotid gland, six involved submandibular gland, and two of them showed involvement of both parotid and submandibular glands [Table 1], [Figure 2]. Imaging characteristics of buccal OSCC involving salivary glands were summarized in [Table 2]. Signal intensity of buccal OSCC on MRI images ranged from hypo intense to iso intense on T1-weighted, hypo intense to hyper intense on T2 weighted and STIR, and heterogeneously enhancing on contrast-enhanced sequences. The diffusion-weighted sequence revealed the restricted diffusion in 4 cases of buccal OSCC [Table 2].
|Figure 2: Buccal OSCC (a) involving the left submandibular gland (b)(sagittal section, T2-weighted contrast-enhanced)|
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|Table 2: Imaging characteristics of buccal OSCC involving salivary glands|
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Observations about salivary glands involved by buccal OSCC
The salivary gland involvement was shown as heterogeneous enhancement; four cases showed through direct spread from the lesion, five cases were involved by spread from adjacent lymph nodes, and a case revealed multiple necrotic metastatic intra parotid lymph nodes [Table 3].
|Table 3: Mode of involvement and imaging characteristics of involved salivary glands in buccal OSCC|
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MRI features with suspicion of salivary gland involvement
In addition to the clear or obvious salivary involvement by buccal OSCC, the careful interpretation of MRI images revealed findings pertaining to salivary glands that may raise the suspicion of its involvement. These MRI features included unilaterally bulky or enhancing gland, altered signal intensity of glandular architecture, involvement of masticator space, and loss of fat planes. Notably, these features were observed in 21 cases (23.07%) of buccal OSCC, suggesting possible salivary involvement.
| Discussion|| |
In the present study, the involved 10 buccal OSCC cases were in tumor stage 4 with N2b and N2c; only one case was in stage 3, which was corresponding to the findings by Naidu et al. and Chen et al., According to O'Brien staging, a tumor size of more than 2 cm and invasion depths more than 5 mm is associated with greater involvement of parotid gland.
Salivary gland involvement by buccal OSCC
The ipsilateral salivary gland involvement was corresponding to most of the previous studies.,, However, Shivakumar et al., reported contralateral intra-parotid node involvement.
In the present study, out of 10 buccal OSCC cases, six cases involved submandibular gland, two cases involved parotid gland, and two cases showed involvement of both parotid and submandibular glands. The present study observation of lesser parotid gland (2.19%) involvement than submandibular (6.59%) was in contradiction to the findings of various previous studies.,, Stanley et al. found nine out 20 to be metastatic malignancies.
The various previous studies assessed submandibular gland involvement by OSCC and revealed their observations.,,,,,,,
Mode of involvement of salivary gland by buccal OSCC
The four involved cases showed direct spread from the lesion and five cases from adjacent lymph node. Notably, one case revealed multiple necrotic intra parotid lymph nodes. This observation was in accordance with studies by Panda et al. and Chen et al., Contradictorily, the metastatic spread is extremely rare in case of submandibular gland.,,,, A study by Fives et al. established a novel way of involvement through a spread along Wharton's ducts. The intra parotid lymph nodes are at risk for nodal metastasis.,,,,,
Locoregional failure of buccal OSCC vis-a-vis salivary gland involvement
There are no rigid boundaries of the buccal space; hence, buccal OSCCs could spread to multiple oral sub sites and/or adjacent structures, such as Stensen's duct, gingivobuccal sulcus, pterygomandibular raphe, retromolar trigone, floor of mouth, masticatory muscles and space, bone, skin, pharynx, investing fascia, skull base, and salivary glands.,, Additionally, accessory parotid tissue may be present in the buccal space just anterior to the parotid gland in around 20% of people.,
| Conclusion|| |
The present study showed greater involvement of salivary gland, especially the submandibular gland than previously. Imaging should be considered as an essential adjunct in evaluation considering the limitations in clinical and histopathological evaluation, although the radiological findings necessitate confirmation by histopathological evaluation.
In the present study, the careful work out of the MRI images revealed features indicating the future possibilities of salivary gland involvement in such cases in addition to clear or obvious involvement. This may be crucial especially in cases of delayed interventions. Such cases with suspicion may need long-term follow-ups considering the possibility of recurrence.
The study revealed the considerable proportion of buccal OSCC cases that involved salivary gland underscoring the need of ruling out salivary gland involvement using systematic work out, especially in cases with occult involvement.
Limitations and future prospects
The study could not include the long-term follow-up of buccal OSCC cases with radiological features with suspicion of future salivary involvement. The study has laid a platform towards the research in this direction; future study may be conducted with long-term follow-up.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]