Li He Shaun Lim, Luo Baiwen, Sharon Chan Pei Yi, Po Yin Tang, Min Wei Chen, Ru Xin Wong, Toh Tan Boon, Edward Kai-Hua Chow, Mohamad Farid Bin Harunal Rashid, and Valerie Shiwen Yang
Background: Gastrointestinal Stromal Tumours (GIST) are c-kit positive mesenchymal tumours that constitute the most common nonepithelial neoplasms of the gastrointestinal tract, commonly metastasizing to the liver and peritoneum. Intracranial metastasis of GIST is extremely rare, with only 19 cases previously reported worldwide, thus presenting a diagnostic challenge and unique treatment considerations.
Case presentation: A 49-year-old gentleman presented with an acute onset of left-sided weakness and an unsteady gait. His past medical history is significant for pulmonary cryptococcosis and localised high risk gastric GIST harbouring KIT exon 11 deletion. He had undergone a R0 gastric wedge resection six years ago, completed three years of adjuvant imatinib, and had been on routine surveillance for the past three years.
A computed tomography and magnetic resonance imaging scan of the brain revealed a large intra-axial lesion in the right parietal lobe and two smaller brain lesions. Further imaging studies of the chest, abdomen and pelvis found no evidence of local recurrence of GIST, and no evidence of distant metastases. A right craniotomy and excision of the right parietal lobe lesion was performed. Immunohistochemical examination demonstrated malignant spindled to epithelioid cells that were strongly positive for CD34, CD117 and DOG1, establishing the diagnosis of GIST. Further mutational analysis revealed a 24-nucleotide deletion in exon 11 consistent with the mutation seen in the primary gastric GIST resected six years ago. The patient was subsequently treated with palliative systemic imatinib with good response.
Conclusions: Isolated intracranial metastasis of GIST is exceedingly rare. We describe a treatment strategy that appears effective for patients with intracranial GIST metastasis, which includes surgical resection and palliative systemic treatment with imatinib. Further work is needed to determine the disease and patient factors which predispose to development of brain metastases in GIST and whether specific mutations are associated with distinct patterns of metastasis.
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