PRRX-NCOA1/2 rearrangement characterizes a distinctive fibroblastic neoplasm.

摘要: Fibroblastic/myofibroblastic neoplasms represent a broad, and occasionally diagnostically challenging, category of soft tissue neoplasms. A subset these tumors defy conventional classification. However, with the advent next-generation sequencing, identification disease-defining molecular alterations is gradually improving their subclassification. Following two index cases distinctive fibroblastic neoplasm fusion gene involving PRRX1 NCOA1, we performed retrospective review to further characterize this entity. We identified additional cases, including one between NCOA2. The average patient age was 38 years, three patients were female. Two occurred on neck, others involved groin thigh. Tumors centered in subcutis ranged from 2.3 14.0 cm (average 5.8 cm). Morphologically, they predominantly hypocellular, focal hypercellularity. They composed monomorphic spindle-stellate cells vague fascicular pattern. nuclei bland only rare mitotic activity, occasional multinucleation. intervening stroma typically abundant myxoid collagenous, frequent rope-like collagen bundles. Three had prominent vasculature ranging numerous small curvilinear vessels ectatic branching staghorn-like vessels. Immunohistochemistry negative for desmin, smooth muscle actin, S100, CD34, keratin, epithelial membrane antigen. Each treated by simple excision none associated local recurrence or metastasis. Based unique morphological attributes, believe represents novel tumor which have tentatively proposed name "PRRX-NCOAx-rearranged tumor."