[High-grade gliomas with H3 G34R mutation: a clinicopathological study]

Objective: To analyze the clinicopathological features and probable mechanisms of high-grade gliomas with H3 G34R mutation. Methods: Five cases of high-grade gliomas with H3 G34R mutation were collected at Xuanwu Hospital, Capital Medical University, Beijing, China, from 2016 to 2019. The clinical and pathological data for each case was retrospectively reviewed. Results: The 5 patients (2 males and 3 females) aged from 15 to 45 years (mean 23 years), and had a history of headache or motor weakness. Four of them were younger than 20 years of age. Magnetic resonance imaging showed that the lesions of 3 cases were seen separately in frontal lobe, parietal lobe or temporal lobe, 1 case involved both frontal lobe and parietal lobe, and otherwise multiple lobes were involved in 1 case. Contrast enhancement could be observed in 2 cases. Pathological examination showed that glioblastoma was the most common entity, with or without primitive neuronal component. All 5 cases showed that H3 G34R was diffusely positive in tumor nuclei with ATRX loss. Moreover, p53 was overexpressed in 4 cases. None of them showed Olig2 expression. Two patients showed disease progression after surgery at 18 months and 24 months, respectively. The latter of the two deceased 3 months after tumor progression. Conclusions: The clinicopathological and molecular genetics features of high-grade gliomas with H3 G34R mutation have relatively similar clinicopathological and genetic features, and more commonly seen in young adults (vs. older adults). Thus, these tumors may be discussed further as a distinct tumor entity.