Figure 4

Both the tumour associated with the stomach and the nodules in the heart showed strong and diffuse positive staining for smooth muscle actin (mouse monoclonal antihuman smooth muscle actin visualized by staining with AEC (3-amino-9ethylcarbazole) labelled secondary antibody, Dako Cytomation, Glostrup, Denmark), prompting a diagnosis of a leiomyosarcoma. Here, positive neoplastic cells (red) are infiltrating (from the left to the right side) in between the negative myocardial cells. Note that also the smooth muscle cells of vessels show strong positive staining (as expected). (anti-smooth muscle actin and HE, 100×).