Liu, Huifei

We report comprehensive characterization of an unusual collision tumor comprising extramedullary plasmacytomas and nasopharyngeal angiofibroma in a pediatric patient, which has yet to be reported. Histologically, the nasopharyngeal angiofibroma showed typical morphology with a diffuse, dense plasmacytic infiltrate in the stroma. The neoplastic plasma cells showed a spectrum of well-differentiated, plasmablastic, and anaplastic morphology, Epstein-Barr virus encoded RNA (EBER) positivity, and aberrant immunophenotype. Fluorescence in situ hybridization using a plasma cell myeloma targeted panel detected gains of 1q21.3 ( CKS1B, x3), 3q27 ( BCL6, x4), and 11q22.3 ( ATM, x3), but no rearrangement of ALK and MYC. A 50-gene next generation sequencing lymphoma panel failed to detect any pathogenic mutation. Plasmacytoma with EBER positivity and plasmablastic morphology must be distinguished from plasmablastic lymphoma due to different clinical management and prognosis. This case highlights the importance of a thorough pathological evaluation of a mass lesion with synchronous neoplastic processes.

Context.— Pleomorphic hyalinizing angiectatic tumor (PHAT) of soft parts, hemosiderotic fibrolipomatous tumor (HFLT), and myxoinflammatory fibroblastic sarcoma (MIFS) are 3 distinct entities of low-grade spindle cell mesenchymal neoplasm. These tumors have similar clinical presentations and partially overlapping but distinctive pathologic features. A recurrent translocation, t(1;10)(p22;q24), has been detected in a subset of PHAT, HFLT, MIFS, and HFLT/MIFS hybrid cases. Translocation t(1;10)(p22;q24) involves transforming growth factor β-receptor 3 (TGFBR3) and meningioma-expressed antigen 5 (MGEA5) genes on chromosomes 1p22 and 10q24, respectively. However, the percentage of translocation in PHAT, HFLT, and MIFS varies significantly among different studies. The relationship among these tumors has been a controversial topic among experts. Objective.— To discuss the diagnostic and functional significance of translocation t(1;10)(p22;q24) TGFBR3/MGEA5 rearrangement in HFLT, PHAT, and MIFS. Data Sources.— PubMed was used for this study. Conclusions.— Diagnosis of HFLT, PHAT, and MIFS is challenging because of a lack of unique morphologic, immunophenotypic, molecular, and cytogenetic markers. The recurrent t(1;10)(p22;q24) translocation and/or TGFBR3/MGEA5 rearrangement was reported in 55 patients, with a relatively even distribution among HFLT, PHAT, and MIFS (17 HFLT, 15 MIFS, 13 MIFS/HFLT, and 10 PHAT). This indicates that current morphology-based diagnostic criteria do not identify reliably the subset of soft tissue tumor with t(1;10) translocation. Genetic heterogeneity of these tumors is supported by the recent detection of a mutually exclusive, second recurrent genetic change, t(7;17) TOM1L2-BRAF translocation or BRAF amplification, in a subset of MIFS.