Clinicopathological Features and HOX Transcript Antisense RNA In Situ Hybridization Detection of Myxopapillary...

Objective To summarize the clinicopathological features,immunohistochemical characteristics,HOX transcript antisense RNA(HOTAIR)in situ hybridization status,treatment,and prognosis of myxopapillary ependymoma(MPE). Methods A total of 17 patients diagnosed with MPE based on pathological evidence in the Department of Pathology of Peking Union Medical College Hospital from November 2006 to July 2023 were selected,and the clinicopathological data of these patients were collected.Immunohistochemical staining for trimethylation at lysine 27 of histone H3 (H3K27me3),glial fibrillary acidic protein(GFAP),and epithelial membrane antigen(EMA)and alcian blue-periodic acid Schiff(AB-PAS)staining were performed in all the patients.Sixteen patients with spinal ependymomas were selected as the control group.Tissue microarrays were prepared from 17 MPE patients and the control group.HOTAIR ISH was performed and semi-quantitatively scored,and the scores of the two groups were compared by the Wilcoxon rank-sum test. Results The 17 MPE patients aged 14-64 years,with the mean age of(37.48±16.10)years and the male-to-female ratio of 0.7∶1.Their clinical manifestations mainly included lumbosacral and lower limb pains.Microscopically,tumor cells were arranged in a papillary pattern around fibrovascular axis,with abundant myxoid materials,and tumor cells were arranged in a loose meshwork in some patients.The immunohistochemical staining results showed that 17(100%),10(58.82%),and 8(47.06%)patients expressed GFAP,EMA,and D2-40,respectively,and 2(11.76%)patients lacked expression of H3K27me3.AB-PAS staining showed blue myxoid materials in all the 17(100%)patients.HOTAIR was expressed in both MPE and control groups,with higher semi-quantitative score in the MPE group than in the control group(P=0.004).Twelve patients were followed up,with a median follow-up period of 65.50 months,during which three patients showed recurrence.Conclusions MPE exhibits typical pathological features,and the combination with immunohistochemical staining for GFAP and EMA as well as AB-PAS staining facilitates diagnosis of this disease.A small number of patients loss the expression of H3K27me3.HOTAIR is highly expressed in MPE but lacks specificity,which limits its auxiliary diagnostic value.The overall prognosis of MPE is favorable,with a few patients experiencing recurrence.