Glioblastoma pseudoprogression

Case contributed by A.Prof Frank Gaillard

Presentation

Headache and seizure.

Patient Data

Age: 65 years
MRI

A peripherally enhancing mass with central non-enhancement is seen in the inferior parietal lobule with surrounding edema. Some non-enhancing tumor appears present below the mass. Features are those of a high-grade glioma (glioblastoma). 

The patient went on to have a resection. 

Histology

MICROSCOPIC DESCRIPTION: The sections show features of a densely cellular astrocytic tumour. The tumour cells have hyperchromatic and pleomorphic nuclei. Some neoplastic gemistocytes are present. Scattered mitotic figures are identified. There are foci of microvascular proliferation. Areas of palisaded necrosis are present. No oligodendroglial component is seen. The features are those of glioblastoma. Small numbers of tumour cells are p53 positive. IDH1-R132H immunostain is negative. ATRX shows no loss of staining (non-mutated).

FINAL DIAGNOSIS: glioblastoma, IDH-wild-type (WHO Grade IV).

Treatment

The patient was commenced on routine Stupp protocol.

MRI

MRI - 2 weeks post surgery

Expected postoperative appearances with minimal enhancement at the resection margins compatible with post-surgical change. Note: no residual enhancing tissue was present on the immediate post-op scan (not shown). 

MRI

MRI - 6 weeks post surgery

6 weeks post op scan demonstrates more pronounced enhancement along the resection margins. Marginal increase in T2 signal elevation around the cavity. 

MRI

MRI - 17 weeks (4 months) post surgery

Approximately 4 months post surgery, after radiotherapy has finished, there intense peripheral enhancement and florid vasogenic edema around the lesion. The enhancing component demonstrates only minor elevation of cerebral blood volume (rCBV) and only thin reduction of ADC values, difficult to interpret due to the presence of blood products best seen on SWI. MRS (not shown) was equivocal dominated by lipid-lactate peak. 

It was felt that most of the findings were compatible with pseudoprogression rather than true progression. 

MRI

MRI - 21 weeks (5 months) post surgery

Repeat MRI a month after the last one (5 months post surgery) continued to demonstrate prominent contrast enhancement and edema. CBV remains relatively low. ADC values are generally facilitated. MRS is dominated by lipid lactate with only small choline elevation. 

Case Discussion

Despite the opinion that most of the changes seen were likely to represent pseudoprogression the patient has substantial symptoms from mass effect not improved with steroids. The decision was made to perform a repeat biopsy/resection of the enhancing component. 

Histology

MICROSCOPIC DESCRIPTION:

Sections show predominantly necrotic tissue with dystrophic calcification. Fragments of viable tumor are present demonstrating moderate nuclear and cellular pleomorphism. No mitoses or microvascular proliferation are identified. Immunohistochemistry results show tumor cells stain: GFAP: Positive IDH-l R132H: Negative (not mutated) ATRX: Positive (not mutated) p53: Negative Topoisomerase labeling index: Approximately 10%.

FINAL DIAGNOSIS: Predominantly necrotic, residual/recurrent Glioblastoma, IDH-l wild-type (WHO Grade IV).

Discussion

As is usually the case, histology demonstrated a combination of treatment effect and tumor. The issue is not whether or not there is any tumor present, but rather which process dominates. In this instance, the imaging findings and histology are consistent with pseudoprogression being the dominant process. The patient is thus being kept on maintenance Temazolamide and edema and enhancement are abating. 

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Case information

rID: 59198
Published: 27th Mar 2018
Last edited: 28th Mar 2018
Inclusion in quiz mode: Included

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