gms | German Medical Science

Objective: Inflammatory disorders occasionally present as intracranial mass lesions that cannot be distinguished clinically or radiologically from an intracranial tumor. Despite the enormous evolution in the noninvasive diagnostic methods, pathological tissue examination often remains the last step in establishing the proper diagnosis.

Method: Patient data sets from 3066 surgeries with intracranial mass lesions performed within a 10-year period were evaluated in a retrospective study. Sixty-five patients (2.1%) were identified, in whom the histological examination confirmed an inflammatory nature of the intracranial mass. Clinical and radiological data were collected and analysed.

Results: There were 35 women and 30 men. Age ranged between 8 and 106 years (mean age 52 years). In 58 patients (89%) only one lesion was identified on MRI, and in the other 7 patients (11%) two or more lesions were identified. The diameter of the mass lesion varied between 0.9 and 7 cm (mean diameter 2.5 cm). Lesions enhanced homogeneously with gadolinium in 27 patients (41.5%), heterogeneously in 14 (21.5%), ring-shaped in 14 (21.5%), and did not enhance at all in 10 patients (15.5%). The location of the lesions were as follows: 29 intracerebral, 9 intraorbital, 8 intracerebellar, 6 in the cerebellopontine angle, 5 in the brainstem, 5 intra-/suprasellar, 4 meningeal, 2 in the optical nerve, 6 in other locations. The histological results were as follows: 12 patients (18%) had a specific granulomatous inflammation (5 toxoplasmosis, 2 tuberculosis, 3 other bacterial infection, 1 mycotic infection, and 1 taenia solium infection); 38 patients (58%) had an unspecific granulomatous inflammation (10 foreign body reaction after prior surgery, 6 organized hematoma or infarction, 5 cholesterol granuloma, 3 granulomatous vasculitis, 2 sarcoidosis, 12 others). In 5 patients (8%) an inflammatory demyelinating disorder was diagnosed. In 10 patients (15%) unclassified inflammatory infiltrations were observed.

Conclusions: Inflammatory disorder can mimic all forms of intracranial tumors and therefore should be considered in the differential diagnosis of a mass lesion. The difficulties encountered in establishing the correct diagnosis of inflammatory disease are related to the etiologies, the radiologic appearance and the clinical presentation. When other diagnostic methods failed to establish the diagnosis, a surgical biopsy should be obtained to confirm the diagnosis before a therapeutic strategy is chosen.