Aspergilloma Masquerading as Meningioma: An Experience of Two Cases and Review of Literature
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.266244
Source of Support: None, Conflict of Interest: None
Fungal infections of the central nervous system are rare and usually occur in immunocompromised patients. They may present clinically and radiologically such as a space-occupying lesion (SOL). Such lesions, especially when extraaxial, keep masquerading as tumors, such as meningioma, owing to similar radiographic appearance. However, such fungal infections have a very poor prognosis in light of angioinvasion and late recognition. There have been a few such reported cases reiterating this observation, making early diagnosis and treatment with maximal surgical resection and antifungal agents imperative for better clinical outcome. Moreover, surgery in such cases without prior suspicion can be dangerous. We present our experience of two such cases of aspergilloma masquerading preoperatively as meningioma.
A 30-year-old male presented to our emergency department with one episode of generalized tonic–clonic seizure. He complained of progressive diminution of vision in the right eye along with occasional right-sided headache for the last 6 months. There was no history suggestive of any immunosuppressive state. On examination, perception of light was positive on the right side with fundus examination revealing right primary optic atrophy. There was no other neurological deficit. Hematological and biochemical investigations were normal except for the slightly raised leukocyte count of 16000 per mm 3. His computed tomography (CT) of the head revealed subarachnoid hemorrhage in the interhemispheric fissure and right sylvian fissure. Contrast-enhanced magnetic resonance imaging (MRI) revealed extraaxial, right medial temporal enhancing lesion which was straddling the planum sphenoid and right anterior clinoid process (measuring 24 × 12 × 24 mm) and compressing the chiasm [Figure 1]. Impression was meningioma based on these findings. His cerebral angiography showed bilobed, broad-necked right internal cerebral artery (ICA) bifurcation aneurysm and vasospasm in the right ICA communicating segment. He was operated with a diagnosis of meningioma with ICA aneurysm with the plan of aneurysm clipping and tumor excision. The lesion was whitish, soft-to-firm with gritty areas straddling the clinoid, and extending over the planum. It was densely adherent to the ICA, and hence, a subtotal excision was performed. A provisional diagnosis of fungal granuloma was made and later confirmed by histopathology as aspergilloma. He was started on Amphotericin B. Patient recovered well with a Glasgow coma scale (GCS) score of E4VtM6 after surgery.
His neurological status deteriorated on postoperative day 6. His CT showed increased mass effect with midline shift towards left for which right frontotemporoparietal decompressive craniectomy was done, following which his GCS improved to E4VtM6. He developed hydrocephalous later and required insertion of ventriculoperitoneal shunt. He was recuperating well but developed fresh subarachnoid hemorrhage with intraventricular hemorrhage and died 4 weeks later.
A 34-year-old female presented to our emergency department after an episode of generalized tonic–clonic seizure. She had a history of headache for the last 6 weeks. Her GCS in the emergency room was E2VtM4. Magnetic resonance imaging (MRI) showed a large heterogenous extraaxial lesion centered on the right lateral sphenoid wing, and a provisional diagnosis of right sphenoid wing meningioma was made [Figure 2]A. She underwent right frontotemporoparietal craniotomy and Simpson's grade 3 excision of the tumor. The lesion was grayish white, soft-to-firm, moderately vascular, and was found attached to greater wing of sphenoid; hence, a diagnosis of meningioma was considered. The brain was edematous at the time of closure for which lax duroplasty was done. On postoperative day 1, patient had a GCS of E1VtM2, and CT revealed a large infarct in the middle cerebral artery (MCA) and posterior cerebral artery (PCA) distribution leading to right temporal lobe edema. Histopathological examination revealed a diagnosis of aspergilloma with septate fungal hyphae and giant cells [Figure 2]B, and she was immediately started on voriconazole in light of this finding. However, she deteriorated 6 days following the surgery and died.
Intracranial aspergillosis presenting as a SOL in the brain is a rare entity. It usually spreads hematogenously from a pulmonary source or arises primarily from paranasal sinuses and spreads intracranially by contiguous spread and by eroding through the base of the skull. Thus, in cases with intracranial SOL with coexistent sinopulmonary fungal infections, one must consider fungal lesion to be the most likely differential.
However, none of the cases that we present here and a majority of those documented in the literature had any signs of primary pathology in the lungs or in paranasal sinuses, suggesting that obscure primary may also be seen in immunocompetent patients. This might be the cause of a low index of suspicion in these cases. In nearly all the cases of intracranial aspergilloma reported in the literature, the patients were immunocompetent, as seen in our cases as well.,,, It is probably because granuloma formation required for such presentation occurs only when immune system is functioning well. The clinical and radiological picture of a fungal granuloma is consistent with meningioma, which remains the usual preoperative diagnosis in such cases. On reviewing the literature, we came across a few reported cases of aspergilloma mimicking a meningioma [Table 1].
There are few subtle differences in MRI findings, which may give a clue towards fungal etiology. Aspergillus is isointense to hypointense on T1 weighted, hypointense on T2 weighted, and shows homogenous contrast enhancement following gadolinium injection. On the other hand, meningioma shows hyperintensity in the T2-weighted images. This difference is attributable to high iron content in Aspergillus. Rarely, angioinvasive fungi can cause plaque-like thickening of dura and mimic en-plaque meningiomas. On reviewing the literature, we came across a few radiological markers, which can distinguish the two entities,, as summarized in [Table 2].
However, mostly diagnosis of aspergilloma is made only after the histopathology report is available, as found by Crivelli et al. It is also noted that, because fungal infection is not suspected even intraoperatively, fungal cultures are usually not sent.
Aspergillus can lyze the vascular wall resulting in secondary vascular complications such as aneurysms, intracranial hemorrhage, or infarcts, further complicating the clinical course. This seems to be a major reason for the dismal outcome in a majority of such patients. In both of our cases, the ultimate cause for death were cerebrovascular complications, which seem to occur with greater frequency postoperatively after the fungal ball has been manipulated during surgery, as observed by Verma et al. Their patient was found to have left MCA infarct on postoperative day 2 and died 2 weeks after the surgery following initial improvement. However, Crivelli et al. and Zafar et al. reported favorable long-term outcomes after starting the antifungal therapy. The reason for this might be the location of the lesion which was the optic foramen  and orbit, respectively. We suspect that the distance of the lesion from major vascular structures rendered these patients less likely to suffer ischemic complications, as observed by us and Verma et al.
A high degree of suspicion with early diagnosis and initiation of antifungal therapy seems to be the only way to improve the outcome of this highly fatal disease. Schwartz et al., reported that voriconazole is more efficacious than amphotericin B in the management of central nervous system Aspergillus. We are of the opinion that starting antifungal therapy with new agents such as voriconazole preoperatively and radical surgical removal before angioinvasion sets in under antifungal cover is the answer to this elusive and fatal disease.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]