PMC5843968_01
Preoperative MRI revealing a left occipital mass mimicking glioblastoma (left upper: T1-weighted image, right upper: T2-weighted image, left lower: diffusion-weighted image, right lower: Gd enhancement)
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F1
Contrast-enhanced magnetic resonance imaging (MRI) showed heterogeneous enhancement in the left occipital lobe [Figure 1].
Intraoperative picture revealing the red fluorescent tumor under 5-aminolevlinic acid fluorescence (left: no fluorescence, right; with fluorescence)
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F2
We administered 5-ALA (Nobelpharma, Tokyo, Japan) at 20 mg/kg prior to her procedure, and biopsied the internal lesion that appeared as red fluorescence under blue light (ZEISS OPMI PENTERO 900) [Figure 2].
HE stain and immunohistochemistry (a) HE, (b) CD68, (c) GFAP, (d) PEPT1, (e) ABCG2, (f) FECH. All of them are x200. HE stain shows aggregation of macrophages and lymphocytes and no tumor cells because of high expression of CD68 that prove the presence of macrophages and normal expression of GFAP that prove no tumor cells. High expression of PEPT1 and no expression of ABCG2 and FECH indicates increased accumulation of intracellular PpIX
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F3
Histopathological examination with hematoxylin-eosin (HE) staining revealed [Figure 3a] signs of infection, inflammation characterized by the accumulation of neutrophils, lymphocytes, and macrophages positive for CD68 in immunohistochemistry (IHC) [Figure 3b]. We determined that the cause of the intraoperative fluorescence was inflammatory change and ruled out GBM [Figure 3c]. Because specific enzymes or transporters in the porphyrin-biosynthesis pathway are factors in 5-ALA-induced false-positive fluorescence, we performed an analysis with IHC and found high expression of peptide transporter 1 (PEPT1) [Figure 3d] and low expression of ATP-binding cassette transporter G2 (ABCG2) [Figure 3e] and ferrochelatase (FECH) [Figure 3f].
Postoperative MRI at 30 months revealing no recurrence of the lesion in the left occipital lobe (left: Gd enhancement, center: T2-weighted image, right: diffusion-weighted image)
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F4
Follow-up MRI at 30 months showed no recurrence and an unchanged postoperative cavity [Figure 4].