Superficial CD34‐positive fibroblastic tumor and PRDM10‐rearranged soft tissue tumor are overlapping entities: a comprehensive study of 20 cases

• DOI: 10.1111/his.14429
• Publication Date: 2021-06-14T08:21:47Z
• Authors: Raul Perret; Michael Michal; Richard A Carr; Valérie Velasco; Marian Švajdler; Marie Karanian; Alexandra Meurgey; Sandrine Paindavoine; Isabelle Soubeyran; Jean‐Michel Coindre; Romain Boidot; Céline Charon‐Barra; Damien Geneste; Noelle Weingertner; Daniel Pissaloux; Franck Tirode; Jessica Baud; François Le Loarer
• Keywords: Desmin; Comparative genomic hybridization

Superficial CD34-positive fibroblastic tumor (SCD34FT) and PRDM10-rearranged soft tissue (PRDM10-STT) are rare mesenchymal tumors. These lesions have clinicopathological similarities, but their relationship remains controversial. This study aimed to characterise a series of cases SCD34FT PRDM10-STT.Ten each PRDM10-STT were studied using immunohistochemistry, array-comparative genomic hybridisation (aCGH), RNA sequencing exome sequencing. Tumors mainly occurred in young adults, generally small (< 5 cm) arose predominantly the superficial tissues lower extremities. Follow-up data available 15 (SCD34FT, n = 7, median 16 months; PRDM10-STT, 8, 14 months), local recurrences four two 10; 10), while no distant spread was documented. Morphologically, tumors relatively well-circumscribed composed sheets fascicles spindle pleomorphic cells showing low mitotic activity 1/mm²) without necrosis. Other findings included: granular cell change, lipoblast-like cells, ectatic blood vessels with fibrinous material, myxoid stromal changes, metaplastic bone increased (> 1/mm²). All diffusely expressed CD34, pan-keratin desmin commonly seen focally. SynCAM3 12 5; 7), independently fusion status. aCGH profiles 'flat' (PRDM10-STT, 4; SCD34FT, 2) showed recurrent pathogenic mutations 2; 4). Overall, only morphological features exclusively changes (three 10) (two 10).We expand current knowledge on provide additional evidence for considering them as overlapping entities.