|Year : 2022 | Volume
| Issue : 1 | Page : 136-138
What's that in the infratemporal fossa?
Abhishek Mahajan, Renuka Ashtekar, Ujjwal Agarwal, Shreya Shukla
Department of Radiology, Tata Memorial Centre and Homi Bhabha National Institute, Mumbai, Maharashtra, India
|Date of Submission||31-Oct-2021|
|Date of Decision||23-Dec-2021|
|Date of Acceptance||17-Jan-2022|
|Date of Web Publication||24-Feb-2022|
Fellowship in Cancer Imaging, MRes (KCL, London), FRCR (UK), Consultant Radiologist, The Clatterbridge Cancer Centre NHS Foundation Trust, Pembroke Place, Liverpool, L7 8YA
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Mahajan A, Ashtekar R, Agarwal U, Shukla S. What's that in the infratemporal fossa?. Cancer Res Stat Treat 2022;5:136-8
| Case History|| |
A 31-year-old female patient with no prior comorbidities presented with a painless swelling in the left cheek that had been gradually increasing over the preceding 4 years. On clinical examination, the swelling measured 4 cm × 3 cm and was found to be extending up to the zygoma with fullness in the left temporal region. It was intraorally palpable along the vestibule till the upper retromolar trigone posteriorly. Magnetic resonance imaging (MRI) revealed a T1-hypointense and T2-heterogeneously hyperintense enhancing lesion in the left infratemporal fossa (ITF), along with anterior temporal dural enhancement [Figure 1] and [Figure 2]. No significant restriction was observed on diffusion-weighted images.
|Figure 1: Axial T1-weighted (a), T2-weighted (b), and post-contrast images (c and d) demonstrate an ill-defined T1-isointense and T2-heterogeneously hyperintense infiltrative lesion in the left infratemporal fossa, involving the retromolar trigone and the masticator space. On post-contrast images, this lesion shows marked enhancement, with associated subtle dural enhancement (arrow)|
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|Figure 2: Coronal post-contrast images demonstrate the lesion in the left infratemporal fossa, reaching up to the left cavernous sinus with subtle dural enhancement as seen in (a). The lesion is seen involving the temporalis muscle and inferiorly extending into the left buccal space as seen in (b)|
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What is the diagnosis, given the clinical and radiological features, and what should be done next? Once you have finalized your answer, read on.
| Differential diagnoses and further management|| |
The differentials considered were schwannoma, meningeal hemangiopericytoma, extracranial meningioma, and the rare possibility of an inflammatory pseudotumor. Schwannomas show intense enhancement, whereas meningeal hemangiopericytomas often show flow voids with the erosion of the adjacent bone. On MRI, inflammatory pseudotumors are T1-isointense, and T2-hyperintense and show marked post-contrast enhancement. It is difficult to radiologically distinguish these entities from meningiomas, and a histopathological confirmation is often required. In view of the increasing swelling and radiological diagnostic dilemma, a computed tomography (CT)-guided biopsy of the left infratemporal lesion was performed, which revealed a spindle and epithelioid cell tumor arranged in a syncytium infiltrating the fibroadipose tissue along with nuclear inclusions. These findings were suggestive of meningothelial meningioma of the left ITF. The case was subsequently discussed in a multidisciplinary joint clinic, and as surgery would have entailed radical resection with a high risk of postoperative trismus and neurological deficits, a decision was made to follow-up the patient with regular MRI examination. Moreover, as the patient was relatively asymptomatic, no further treatment, apart from referral to the pain clinic, was suggested.
| Final diagnosis|| |
The final diagnosis was meningothelial meningioma of the left infratemporal fossa.
| Discussion|| |
Meningiomas are relatively common, however, extracranial meningiomas constitute only about 1%–2% of all meningiomas. Extracranial meningiomas most commonly involve the scalp, followed by the ear and the temporal bone. Hoye et al. have postulated four theories for extracranial extension pathways:
- Type A: Direct extracranial extension of a primary tumor through foramina, sutures, etc.
- Type B: Extracranial growth from arachnoid cells within sheaths of cranial nerves
- Type C: Extracranial growth from embryonic rests of arachnoid without foraminal or cranial nerve communication
- Type D: Distant metastases of intracranial meningioma
Our case demonstrated temporal dural enhancement, suggesting Type A pattern of spread. Certain theories postulate that extradural meningiomas arise due to the entrapment of meningothelial cells within the skull sutures if congenital or within fracture lines, as in post-traumatic cases. Meningocytes may be trapped in the subcutaneous tissues due to defects in neural tube closure leading to cutaneous meningiomas. Meningiomas may also arise from multipotent mesenchymal cells.
Broadly, meningiomas may be primary intradural (with or without a secondary extradural extension) and primary extradural (rare). Rarely (in 1%–2% of cases) meningiomas are known to arise from ectopic sites such as the head-and-neck, orbit, nose, paranasal sinus, oropharynx, and lungs. Extracranial meningiomas are further classified by Lang et al. as follows:
- Type I: Purely extracalvarial
- Type II: Purely calvarial
- Type III: Calvarial with extracalvarial extension
- Type II and III tumors could be categorized as convexity (C) or skull base (B) lesions. This is clinically relevant, as patients with IIC or IIIC tumors are reported to have lower recurrence rates compared to those with IIB or IIIB tumors.
Imaging features of typical meningiomas include dural-based masses which are T1-and T2-isointense and show characteristic intense enhancement on both MRI and CT scans.
Both intracranial and extracranial meningiomas share radiological features and appear isointense on T1-and T2-weighted images, with avid and homogenous contrast enhancement. Magnetic resonance spectroscopy spectrum of typical meningiomas exhibits a high choline peak (Cho) with low or absent N-acetylaspartate (NAA) and creatine (Cr). A relatively specific marker for meningiomas is the presence of alanine resonance at 3.8 ppm in long echo time sequences. Magnetic resonance perfusion studies of meningiomas generally demonstrate increased relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF). Our patient demonstrated a predominant extracranial component with only a subtle intracranial clue to the diagnosis in the form of temporal dural enhancement. This highlights the importance of MRI in diagnosing meningiomas at uncommon locations.
Rushing et al. in their series of 146 cases of primary extracranial meningiomas showed that meningothelial meningiomas are the most common histological type.
Extracranial meningiomas are characteristically slow-growing neoplasms with good prognosis, with the longest survival being associated with younger age and complete resection. While surgical resection is the mainstay of treatment, complete resection is challenging given the large size, poor margins, and difficult location with high rate of complications, including cranial nerve palsies, facial disfigurement, ophthalmoplegia, and visual disturbances. Thus, a multidisciplinary approach is required, involving both neurosurgical and otorhinolaryngological expertise. Radiotherapy and radiofrequency ablation can be used to reduce the bulk of a large extracranial meningioma before surgery and to reduce the symptoms in palliative cases. As mentioned previously, a careful decision against surgery was made in our case based on the high risk of postoperative complications weighed against the relative benefit in an otherwise asymptomatic patient.
Extracranial meningiomas in the ITF should be distinguished from other ITF tumors, which can occasionally be possible based on imaging features.
- Meningeal hemangiopericytoma: They are typically hyperdense on CT with heterogenous enhancement. Unlike meningiomas, these lesions cause erosion of the adjacent bone without hyperostosis or calcification
- Schwannoma: These are heterogeneously hyperintense on T2-weighted images and may have cystic spaces within, unlike meningiomas which have a more homogeneous signal intensity. They often show intense post-contrast enhancement, similar to meningiomas
- Inflammatory pseudotumor: It is a quasineoplastic lesion consisting of inflammatory cells and myofibroblastic spindle cells and can involve diverse sites in the body, but most commonly involves the lungs and the orbit. On T1-weighted images, it appears hypointense to fat and isointense to muscles and T2-isointense to minimally hyperintense, with marked enhancement. Histopathological examination is the mainstay of diagnosis and reveals inflammatory cell infiltration with numerous lymphocytes and surrounding plasma cells accompanied by fibrosis.
Rare instances of isolated infections of the ITF may mimic tumors as well, with rare recorded cases of tuberculosis and aspergillosis presenting as swelling without fever.
| Conclusion|| |
Extracranial meningioma, particularly in the infratemporal location, is a rare entity and requires a high index of suspicion for early diagnosis. The radiologic features are similar to its intracranial counterpart, which may guide the diagnosis when presented with atypical locations such as the ITF. Knowledge of the various tumors that may be seen in the ITF can help distinguish a meningioma from other tumors.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]