Fig. 3: Histological and molecular findings of synovial sarcoma with an MN1-SSX1 fusion (case 4).
From: Identification of novel SSX1 fusions in synovial sarcoma
The tumor showed alternating loose and dense areas (A), the latter composed of intersecting and swirling fascicles of spindle cells (B). Nuclear palisading was occasionally observed (C). The tumor cells were monomorphic and possessed a high nuclear/cytoplasmic ratio (D). Immunohistochemically, the tumor showed focal strong cytokeratin expression (E), diffuse weak EMA expression (F), and diffuse strong TLE1 (G), and BCOR (H) expressions. SS18-SSX immunostaining was negative (I), while SSX (C-term) immunostaining showed diffuse strong reactivity (J). Targeted RNA sequencing identified in-frame MN1-SSX1 fusion transcripts, which were confirmed using RT-PCR/Sanger sequencing (K).
