Novel morphologic findings in PLAG1‐rearranged soft tissue tumors

• Published in: Genes chromosomes & cancer Vol. 60; no. 8; pp. 577 - 585
• Main Authors: Logan, Suzanna J., Schieffer, Kathleen M., Conces, Miriam R., Stonerock, Eileen, Miller, Anthony R., Fitch, James, LaHaye, Stephanie, Voytovich, Kyle, McGrath, Sean, Magrini, Vincent, White, Peter, Wilson, Richard K., Mardis, Elaine R., Cottrell, Catherine E., Koo, Selene C.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.08.2021; Wiley Subscription Services, Inc
• Subjects: Adolescent; CD34 antigen; Chemotherapy; Child, Preschool; COL3A1; Collagen Type III - genetics; Desmin; DNA-Binding Proteins - genetics; Female; fibromyxoid; fibrovascular; Homeodomain Proteins - genetics; Humans; Male; Mitosis; Neoplasia; Oncogene Proteins, Fusion - genetics; PLAG1; Proteins - genetics; soft tissue; Soft Tissue Neoplasms - genetics; Soft Tissue Neoplasms - pathology; Soft Tissue Neoplasms - surgery; Soft Tissue Neoplasms - therapy; Transcription Factors - genetics; Tumorigenesis; Tumors; ZFHX4; COL3A1; fibrovascular; soft tissue; PLAG1; ZFHX4; fibromyxoid
• ISSN: 1045-2257; 1098-2264
• DOI: 10.1002/gcc.22953

Oncogenesis in PLAG1‐rearranged tumors often results from PLAG1 transcription factor overexpression driven by promoter‐swapping between constitutively expressed fusion partners. PLAG1‐rearranged tumors demonstrate diverse morphologies. This study adds to this morphologic heterogeneity by introducing two tumors with PLAG1 rearrangements that display distinct histologic features. The first arose in the inguinal region of a 3‐year‐old, appeared well‐circumscribed with a multinodular pattern, and harbored two fusions: ZFHX4‐PLAG1 and CHCHD7‐PLAG1. The second arose in the pelvic cavity of a 15‐year‐old girl, was extensively infiltrative and vascularized with an adipocytic component, and demonstrated a COL3A1‐PLAG1 fusion. Both showed low‐grade cytomorphology, scarce mitoses, no necrosis, and expression of CD34 and desmin. The ZFHX4‐/CHCHD7‐PLAG1‐rearranged tumor showed no evidence of recurrence after 5 months. By contrast, the COL3A1‐PLAG1‐rearranged tumor quickly recurred following primary excision with positive margins; subsequent re‐excision with adjuvant chemotherapy resulted in no evidence of recurrence after 2 years. While both tumors show overlap with benign and malignant fibroblastic and fibrovascular neoplasms, they also display divergent features. These cases highlight the importance of appropriate characterization in soft tissue tumors with unusual clinical and histologic characteristics.