case_images: PMC11736860_01
case_images: (a) Sagittal soft-tissue window and (b) axial bone window CT scans show a large mass centered in the sphenoid bone, with resorption of the dorsum sellae and posterior sphenoid wall (arrows, a). Notice the extensive bone resorption in the central skull base (circle, b). (c) Coronal T2 short-tau inversion recovery, (d) sagittal T2-weighted image, and (e) contrast-enhanced sagittal T1-weighted images confirm the presence of a large central skull base mass (arrows, d, e), which abuts the posterior fossa posteriorly. Despite its large size, the mass respects the spheno-occipital synchondrosis (arrowheads, d, e) and restricts the pituitary fossa, with elevation of the pituitary gland (triangle, d, e).
case_images: tap-60-1-84_f001.jpg
case_images: PMC11736860_01_tap-60-1-84_f001.jpg
case_images: f1-tap-60-1-84
case_images: Initial magnetic resonance imaging (MRI) revealed a 42 x 32 x 30 mm mass centered on the clivus and extending to the sphenoid body, partially disrupting the spheno-occipital synchondrosis (Figure 1).
case_images: Photomicrograph showing: (a) Several multinucleated giant cells (hematoxylin and eosin staining; magnification 20x). (b) Scattered mitoses in smaller round cells (hematoxylin and eosin staining; magnification 40x).
case_images: tap-60-1-84_f002.jpg
case_images: PMC11736860_01_tap-60-1-84_f002.jpg
case_images: f2-tap-60-1-84
case_images: Importantly, no necrosis, pleomorphism, or osteoid/chondroid matrix was observed (Figure 2).
case_images: Sequencing electropherogram of a GCTB patient harboring a point mutation, c.103G>T (p.G35W), in the H3-3A gene. DNA was extracted from tumor sections (8 microm) using the Genomic DNA FFPE One-Step Kit for the Diatech MagCore  HF16Plus extractor (RBC Bio-science, Taiwan) according to the manufacturer's instructions. Mutation analysis was performed using PCR amplification of the DNA with a specific intronic primer of exon 2 of H3-3A (LRG_1410, NM_002107.7). Purified PCR products were sequenced using the BigDye Terminator v1.1 cycle sequencing kit (Life Technologies) and a 3130xL Genetic Analyzer (Life Technologies), following the manufacturer's instructions. The electropherogram represents the output from the Sanger sequencing analysis software, identifying a heterozygous missense mutation in the H3-3A gene, c.103G>T (p.G35W). This mutation results from the substitution of G with T, causing a change in amino acid 35 from glycine to tryptophan in the H3-3A protein sequence.
case_images: tap-60-1-84_f003.jpg
case_images: PMC11736860_01_tap-60-1-84_f003.jpg
case_images: f3-tap-60-1-84
case_images: H3.3 p.Gly35Trp mutation (Figure 3): this result raised our curiosity, as the pathogenic molecular variant described in the literature in 90% of GCTBs would be p.G34W (H3.3 p.Gly34Trp mutation). However, we verified that the correct nomenclature of the somatic mutation harbored by GCTBs, referring to the Locus Reference Genomic (LRG_1410; http://www.lrg-sequence.org/) of the H3-3A gene, requires us to describe it as c.103G>T (p.G35W) as also done in a recent case report.