The CD34 positivity, together with typical muscle-markers positivity, as α-SMA and desmin, in an extremely minority of tumours (α-SMA positivity in 6 cases on 40 tested, 15 % and desmine positivity in 2/39 examined cases, 5.1 %), suggest a probable fibroblastic rather than myofibroblastic differentiation. The gene discussed is ACTA1; the disease is neoplasm.