Immunohistochemical evaluation of H3K27 trimethylation in malignant peripheral nerve sheath tumors

Publication date: Available online 31 January 2018 Source:Pathology - Research and Practice Author(s): Hiroshi Otsuka, Kenichi Kohashi, Masato Yoshimoto, Shin Ishihara, Yu Toda, Yuichi Yamada, Hidetaka Yamamoto, Yasuharu Nakashima, Yoshinao Oda The histological definitive diagnosis of malignant peripheral nerve sheath tumor (MPNST) is quite difficult because the morphological features are not specific and no useful immunohistochemical marker has been identified. Loss-of-function mutations in EED or SUZ12, which encode the core subunit of polycomb repressive complex 2 (PRC2), were reported in MPNSTs, and the mutations were shown to cause inactivation of PRC2, leading to loss of trimethylation of histone H3 at lysine 27 (H3K27me3). Immunohistochemistry of H3K27me3 is expected to be a specific marker for MPNSTs. We evaluated immunohistochemical expression of H3K27me3 in MPNSTs with heterologous components and metachronous cases of MPNSTs. Among 145 MPNST samples, 50 (34.5%) showed complete loss of staining, and 45 (31.0%) showed partial loss of staining. Regarding the backgrounds of MPNSTs, 74 samples of neurofibromatosis type 1 (NF-1)-associated MPNST demonstrated 26 (35.1%) complete and 26 (35.1%) partial loss of H3K27me3. Among MPNSTs with heterologous component, almost all of MPNSTs with epithelioid differentiation (8/9 samples, 88.9%) retained H3K27me3, and malignant Triton tumors without epithelioid component lacked H3K27me3 at high rate (91.7%). Five of 20 meta...
Source: Pathology Research and Practice - Category: Pathology Source Type: research