Many cardiac neoplasms lack pathognomonic clinical features and lead to controversial interpretations. As genomic changes may correlate with these malignancies and possibly aid in diagnosis, we studied, using FISH, a polypoid lesion, incidentally found at autopsy on the septal wall of the left ventricle of a 75-year-old male who had died from a heart attack. Histology and immunohistochemistry disclosed atypical stromal cells with irregular voluminous nuclei positive for vimentin and smooth muscle actin, reminiscent of cells previously reported in a subset of nasal polyps showing aneuploidy. The scarce lymphoplasmacytic infiltrate hindering the diagnosis of inflammatory myofibroblastic tumors (IMT) and the presence of atypical cells, promped us to perform FISH: lack of ALK gene rearrangement and aneuploidy were observed in the irregular nuclei, supporting the diagnosis of a pseudosarcomatous myofibroblastic proliferation (PMP). These results stress that IMT and PMP may represent variants within a spectrum of myofibroblastic proliferations/tumours.