Original ArticlesDedifferentiated Liposarcomas With Divergent Myosarcomatous Differentiation Developed in the Internal Trunk A Study of 27 Cases and Comparison to Conventional Dedifferentiated Liposarcomas and LeiomyosarcomasBinh, Matthieu Bui Nguyen, MD*; Guillou, Louis, MD†; Hostein, Isabelle, PhD‡; Château, Marie Christine, MD§; Collin, Francoise, MD∥; Aurias, Alain, PhD¶; Binh, Bui Nguyen, MD♯; Stoeckle, Eberhard, MD**; Coindre, Jean-Michel, MD*Author Information *Department of Pathology, Institut Bergonié and Université Victor Segalen, Bordeaux †University Institute of Pathology, Lausanne, Switzerland ‡Department of Pathology, Institut Bergonié, Bordeaux §Department of Pathology, Val d'Aurelle Cancer Center, Montpellier ∥Department of Pathology, Georges-Francois Leclerc Cancer Center, Dijon ¶Unité INSERM U509, Institut Curie, Paris ♯Department of Oncology, Institut Bergonié **Department of Surgery, Institut Bergonié, Bordeaux, France Supported by the Ligue Nationale Contre le Cancer, committee of Charente-Maritime and committee of Pyrénées Atlantiques and the Institut National Contre le Cancer (INCa). Presented in abstract form at the 94th Annual Meeting of the United States and Canadian Academy of Pathology, San Antonio, March 2005. Reprints: Jean-Michel Coindre, MD, Département de Pathologie, Institut Bergonié, 229 Cours de l'Argonne, 33076 Bordeaux cedex, France (e-mail: email@example.com). The American Journal of Surgical Pathology: October 2007 - Volume 31 - Issue 10 - p 1557-1566 doi: 10.1097/PAS.0b013e31804b4109 Buy Metrics Abstract Dedifferentiated liposarcoma (DLPS) is one of the most frequent sarcomas of the retroperitoneum and represents most undifferentiated sarcomas of the internal trunk. In about 5% cases, the dedifferentiated component is an heterologous sarcoma such as leiomyosarcoma or rhabdomyosarcoma. We reviewed a series of 65 sarcomas with a myogenic differentiation developed in the internal trunk for which initial diagnoses were leiomyosarcoma (37), rhabdomyosarcoma (6), malignant mesenchymoma (6), and DLPS (16). Immunostainings for MDM2, CDK4, alpha smooth actin, desmin, caldesmon, myogenin, c-kit, and progesterone receptor were performed. In 48 cases, the amplification status of MDM2 and CDK4 could be evaluated with quantitative polymerase chain reaction on paraffin-embedded tissues extracted DNAs. After review of the cases, final diagnoses were leiomyosarcoma (35), rhabdomyosarcomatous (20) or leiomyosarcomatous (7) DLPS, probable DLPS (2), and malignant mesenchymoma (1). DLPS were bigger tumors (median: 18.2 cm) than leiomyosarcomas (median: 12 cm). They had a lower 5-year recurrence-free survival than leiomyosarcomas (45% vs. 71%) but a higher 5-year metastasis-free survival (73% vs. 39%). There was no significant difference in overall survival (57% vs. 34%). Outcome of patients with a DLPS with a myosarcomatous component did not differ from conventional DLPS. In conclusion, most sarcomas with a rhabdomyosarcomatous differentiation occurring in the internal trunk of adults are DLPS. Moreover, DLPS with a myogenic component have a low metastatic potential, similar to conventional DLPS and significantly lower to the metastatic potential of leiomyosarcomas. © 2007 Lippincott Williams & Wilkins, Inc.