Glioblastoma presenting with steroid-induced pseudoregression of contrast enhancement on magnetic resonance imaging

Abstract

Corticosteroid-induced reduction in contrast enhancement on radiographic imaging is most commonly associated with lymphoma but has been reported in other entities, including glioma. This finding may represent a diagnostic dilemma. Concern that steroid-induced cytotoxicity obscures histological diagnosis of suspected lymphoma may lead to postponement of a biopsy. If glioma is not considered in the differential diagnosis, reduction in tumor contrast enhancement may be misinterpreted as disease regression rather than a transient radiographic change. We report a case of a patient with an enhancing right temporoparietal mass adjacent to the atrium of the lateral ventricle. After treatment with dexamethasone was started, the mass exhibited marked reduction in contrast enhancement, with symptom improvement. The clinical course suggested lymphoma, and surgery was not performed. Subsequent screening for extra-axial lymphoma was negative. Two weeks later, the patient developed worsening symptoms, and repeat T1-weighted imaging showed interval increase in size and enhancement. The findings suggested a possible diagnosis of malignant glioma. The patient underwent a stereotactic-guided craniotomy for excision of the right temporoparietal mass lesion. Final histological diagnosis was glioblastoma multiforme, World Health Organization grade IV.

Figure 1

(a) Initial contrast-enhanced axial and coronal T1-weighted fast spin echo (FSE) sequence demonstrating an avidly enhancing temporoparietal mass in a 57-year-old female patient who presented with short-term memory loss, headaches, subtle left-sided weakness, and unsteady gait. There is enlargement of the splenium with nodular enhancement within the contralateral corpus callosum. Extensive areas of subependymal and leptomeningeal enhancement (arrowheads) are present. (b) Contrast-enhanced axial spoiled gradient recalled (SPGR) sequence demonstrating overall decreased enhancement with formation of centrally necrotic areas after 5 days of corticosteroid therapy. The patient's improved functional status and the radiographic regression of the mass suggested a diagnosis of lymphoma. (c) Axial and coronal T1-weighted, contrast-enhanced FSE image obtained two weeks later showing increased nodular enhancement along the inferior and medial margins of the dominant mass and evolution of the necrotic areas. These changes suggested a diagnosis of glioma.

Figure 2

Histological slide from the right parietooccipital biopsy with hematoxylin and eosin staining. (a) Low-magnification micrograph showing serpiginous areas of necrosis with pseudopalisading and vascular proliferation (Scale bar = 0.3 mm). (b) High-magnification micrograph showing hyperchromatic nuclei and frequent mitoses (Scale bar = 0.1 mm). These findings are consistent with a diagnosis of glioblastoma, WHO grade IV.