CASE 9120 Published on 07.10.2011

Pneumosinus dilatans with intracranial meningioma

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

Arora A*, Kapoor A, Singh S, Upreti L, Puri SK

Department of Radiodiagnosis, G.B. Pant Hospital and *I.L.B.S Hospital, New Delhi, India.

Patient

40 years, female

Categories
Area of Interest Neuroradiology brain ; No Imaging Technique
Clinical History
A previously healthy 40-year-old lady presented with a long-standing bifrontal headache. Neurological examination was unremarkable.
Imaging Findings
Contrast enhanced MR imaging of brain revealed an enhancing extra-axial mass lesion in the left anterior cranial fossa with mild mass effect over the adjacent left frontal cerebral parenchyma. There was associated asymmetric enlargement of the adjacent left frontal sinus. The enlarged sinus demonstrated bulging convex margins towards the mass lesion. Based on the imaging findings, a pre-operative diagnosis of intra-cranial meningioma with pneumosinus dilatans was suggested and confirmed histopathologically.
Discussion
Pneumosinus dilatans (PSD), first described by Benjamin in 1918, refers to an abnormally dilated air-filled paranasal sinus without radiological evidence of osseous erosion, hyperostosis or mucosal thickening. Pneumosinus dilatans mainly involves the frontal sinus, followed by the sphenoid, maxillary and ethmoid sinuses in descending order of frequency [5]. The exact aetiopathogenesis of PSD remains uncertain.

It is frequently associated with intracranial and orbital meningiomas and arachnoid cysts [3]. Prior to the CT and MRI era, PSD was used as a helpful clue for identifying an underlying intracranial or orbital neoplasm [1, 2, 3]. In patients with progressive vision loss, the presence of sphenoid PSD helped in identifying optic nerve sheath and parasellar meningiomas. PSD is known to be an early sign of meningioma of the anterior chiasmatic angle [6]. Sphenoid sinus PSD can cause progressive optic atrophy and bi-temporal field defects [7].

Although PSD has been conventionally described on plain radiography, it can be very well diagnosed with CT and MR imaging [1, 3, 4]. The diagnostic criterion includes an abnormal enlargement and expansion of an air-filled paranasal sinus. CT of the head and paranasal sinuses is considered the imaging modality of choice [5]. An underlying intracranial lesion, if present, can be better characterised at MR imaging. Treatment of PSD is surgical and is recommended for cosmetic purposes [4].

To conclude, detection of PSD should alert the radiologist to look watchfully for an intracranial mass such as a meningioma or arachnoid cyst, especially when it appears intrinsic to the brain.
Differential Diagnosis List
Meningioma with pneumosinus dilatans
Pneumocele
Hypersinus
Final Diagnosis
Meningioma with pneumosinus dilatans
Case information
URL: https://www.eurorad.org/case/9120
DOI: 10.1594/EURORAD/CASE.9120
ISSN: 1563-4086

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