The cells exhibited a spindle shape and aggressive growth; they also expressed smooth muscle actin, reflecting the original LMS tissue (i.e. smooth muscle cells).
Leiomyosarcomas (LMSs) constitute approximately one quarter of all sarcomas and are usually defined by morphologic criteria and/or immunoreactivity for actin or desmin.
The primary tumor was clearly positive for á-smooth muscle type actin and desmin in moderately differentiated areas and indicated a loss of myogenic differentiation in other regions and therefore was classified as a poorly differentiated LMS.