Frontal lobe fungal abscess

Case contributed by RMH Neuropathology

Presentation

Previous history of renal transplant.

Patient Data

Age: 43
Gender: Male
CT

In the brain there are three ring-enhancing lesions: one in the right frontal lobe and two in the left frontal lobe. The ventricles are normal in size and appearance. There is no midline shift. The basal cisterns are unremarkable. There is a small amount of fluid in the right ethmoid sinus with loss of the lamina papyracea at this location. There is mild mucosal thickening of the left maxillary antrum. The remaining imaged paranasal sinuses are clear. There is no bony destruction. The orbital contents are unremarkable

In the chest, there are innumerable cavitating lesion throughout the lung with air fluid levels. The pleural spaces are clear. The mediastinal structures are unremarkable with no lymphadenopathy. The pericardial space is clear. 

MRI

MRI brain (without contrast)

There a total of 4 supratentorial intra-axial mass lesions demonstrated, scattered throughout bilateral frontal lobes.  On T2-weighted imaging, these lesions demonstrate a low signal rims, with marked surrounding FLAIR high signal, in keeping with surrounding oedema. The central content of three of the lesions (two left frontal and one right posterior frontal), demonstrate internally restricting content.

Minimal susceptibility blooming is demonstrated along the posterior margin of the larger left frontal corona radiata lesion, possibly representing inspissated proteinaceous material or blood products.

There is no hydrocephalus and the midline remains central. There is an equivocal punctate focus of restricted diffusion within the middle of the medulla that cannot be well correlated on other sequences, likely artefact-related.

Conclusion:

There is a total of four intra-axial lesions - two in each of the frontal lobes. The imaging findings of these lesions are consistent with small abscesses - based on the clinical history, likely fungal.

Minimal thickening of the posterior margin of the left ocular globe may represent infective change, however, clinical/fundoscopic correlation advised.

MRI

3 years later

 

Since prior interval studies (not shown, in which marked improvement had occurred) There has been significant increase in the degree of high FLAIR signal in the right frontal and parietal lobe compared to previous. Within this region there appear to be two discrete lesions of susceptibility in keeping with haemorrhage. There is mild increase in mass effect on the right lateral ventricle with no midline shift. The high FLAIR signal in the left frontal lobe has reduced in size and is now seen to surround two discrete lesions, both of which have internal susceptibility in keeping with blood products.

Prosthetic left eye again demonstrated.

CONCLUSION:

Significant increase in oedema and mild mass-effect surrounding at least two right frontal lobe lesions since previous. Reduction in oedema surrounding at least two left frontal lobe lesions. Whether all due to aspergillus, or other pathogens such as nocardia or toxoplasma cannot be determined.

Pathology

MICROSCOPIC DESCRIPTION: The sections show brain parenchyma in which there is a circumscribed lesion with an epicentre at the interface between cortex and white matter. The lesion is multilocular with locules filled with necrotic inflammatory debris. Dystrophic calcification is also noted. The debris is surrounded by a layer of intensely inflamed granulation tissue. Peripheral to this is a layer of fibrous tissue. Brain parenchyma surrounding the lesion shows intense fibrillary astrocytic gliosis and oedema. Focal acute cerebritis is also noted. Fungal elements with morphology of pesudohyphae, hyphae and yeast forms are identified in Grocott and PAS stained sections. No organisms are identified in Gram stained sections. In particular, no filamentous Nocardia-like organisms are seen. No acid fast organisms are seen in Fite and Ziehl-Neelsen stained sections. The features are of an abscess of likely fungal aetiology. No evidence of tumour is seen.

DIAGNOSIS: "Right frontal subcortical lesion": Abscess of likely fungal aetiology.

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Case information

rID: 39747
Case created: 18th Sep 2015
Last edited: 20th Sep 2015
Inclusion in quiz mode: Included

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