Case of mesenchymal tumor with the PPP6R3-USP6 fusion, possible nodular fasciitis with malignant transformation.
Yasuyo TeramuraYukari YamazakiMiwa TanakaYoshiya SugiuraYutaka TakazawaKengo TakeuchiTakayuki NakayamaTakao KanekoYoshiro MushaYuki FunauchiKeisuke AeSeiichi MatsumotoTakuro NakamuraPublished in: Pathology international (2019)
Nodular fasciitis (NF) is a self-limiting benign disease that is characterized by rapid proliferation of fibroblastic and myofibroblastic cells. The characteristic gene fusion containing the USP6 gene is a genetic hallmark of NF and MYH9-USP6 is the most frequent fusion, suggesting that NF is not a reactive condition but a neoplastic disease. Malignant transformation of NF has been reported rarely as a single case associated with the PPP6R3-USP6 fusion. Here we report a case of soft part tumor of which the histological feature was a typical NF but showed aggressive and non-regressing growth with local invasion. Targeted RNA sequencing and fluorescence in situ hybridization analysis identified PPP6R3-USP6 with gene amplification. These findings indicate that the present case is the second case of malignant NF, and we suggest potential malignant transformation in certain NF cases.
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