Dedifferentiated liposarcoma with a paraganglioma-like histologic pattern: a case report and review of the literature.

A 53-year-old man presented with a 4-month history of increasing abdominal discomfort and distension. A large retroperitoneal mass was found on imaging. Image-guided needle core biopsy demonstrated a poorly differentiated malignant neoplasm. A 30 x 32 x 33-cm soft tissue mass was removed. Microscopically, the tumor consisted of predominantly epithelioid malignant cells arranged in a paraganglioma-like growth pattern. Immunohistochemically, these cells were strongly positive for neuron-specific enolase. Stains for synaptophysin and chromogranin, however, were negative. There was no ultrastructural evidence of neuroendocrine differentiation. Adjacent sarcomatous areas were composed of spindled cells arranged in storiform and fibrosarcoma-like growth patterns. A small area of well-differentiated liposarcoma was identified, and a diagnosis of dedifferentiated liposarcoma was established. To the best of our knowledge, this represents the first reported case of dedifferentiated liposarcoma with a paraganglioma-like histologic pattern. A brief review focusing on the morphologic variations of dedifferentiated liposarcoma is also presented.