Paratesticular Leiomyosarcoma : Differential Diagnosis
Some leiomyosarcomas show numerous bizarre pleomorphic nuclei as seen in this case. They may resemble undifferentiated pleomorphic sarcomas (malignant fibrous histiocytoma). Usually, there are focal areas within the tumor with typical smooth muscle differentiation which point to the correct diagnosis. Other differential diagnostic considerations include : subcutaneous scrotal leiomyomas with bizarre nuclei (they don't show increased mitotic activity), fibrous mesothelioma (associated with hydrocele, history of asbestos exposure, infiltrating margins, more collagenized background than leiomyosarcoma, lack of actin expression, and diffuse rather than focal keratin expression), fibrous pseudotumors (nuclear atypia is not striking, more prominent inflammatory component than in leiomyosarcomas), dedifferentiated liposarcoma (usually have adjacent foci of more typical well-differentiated liposarcoma), deep fibromatosis (more infiltrative growth than leiomyosarcomas, sweeping fascicles of fibroblastic and myofibroblastic cells, tapering rather than blunt ended nuclei).