Gemistocytic astrocytoma (anaplastic)
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Left frontoparietal para-falcine ill-defined cortical based space-occupying lesion with gyral swelling showing the following :
- size: averaging 2.5x1.5x1.8 cm, in maximum AP, SS and CC dimensions
- signal pattern: T1 hypo, T2 hyperintensity with no detected appreciable post-contrast enhancement
- vasogenic edema: surrounded by grade I perifocal edema
- mass effect: mild effacement of the related cortical sulci
- enhancement pattern: heterogeneous enhancement with small central none enhancing spot
- SWI: no blooming
- diffusion-weighted imaging: the lesion shows no diffusion restriction. The mean ADC value of the lesion = 1.382 x 10-3 mm2/sec
Spectroscopy (TE 135 msec)
- Cho/Cr ratio =0.81
- Cho/NAA ratio=1.56
- NAA/Cho ratio = 0.64
- NAA/Cr ratio = 0.52
- Lactate peak is detected
The short echo time TE 30 msec spectroscopy showed reduction in the choline levels with high MI levels.
The imaging features are suspicious for neoplastic lesion, especially when furthur assessed using MRI perfusion and diffusion tensor imaging (not available). The patient underwent surgery and pathology revealed gemistocytic anaplastic astrocytoma. It has a variety of imaging appearances, with the gemiocytic type characterized by post-contrast enhancement. Anaplastic astrocytomas lack frank necrosis, unlike glioblastomas.
Specimen: left frontoparietal intra-axial lesion, excision biopsy.
Gross: several grayish white friable pieces of tissue about 6 cm in aggregate.
- cellular tumor tissue formed of astrocytic cells showing oval vesicular nuclei against a fibrillary background
- focal nuclear atypia, as well as mitotic figures, are noted
- a prominent gemistocytic component is identified
- no necrosis or vascular proliferation are noted in submitted biopsy
Case courtesy Dr. Mohaked Kaed, Radiology consultant, Alexandria, Egypt.