In summary, we described four extra-abdominal round cell/epithelioid mesenchymal neoplasms sharing EWSR1::ATF1 fusions, frequent expression of epithelial and neuroendocrine markers, occasional aberrant expression of ALK and MUC4, but not fitting with any currently defined mesenchymal neoplasm. The gene discussed is ATF1; the disease is mesenchymal cell neoplasm.