Metastasizing gastric epithelioid leiomyosarcomas (leiomyoblastomas) in young individuals with long-term survival.

RESULTS. Four patients with metastasizing epithelioid leiomyosarcoma of the stomach, three females and one male (15, 20, 22, and 25 years of age, respectively), are reported. Two patients had recurrent tumors in the gastric remnant. Liver metastases occurred in all patients, three of whom had lymph node metastases; two had peritoneal metastases. The patients are alive at 17, 19, 27 and 48 years after the diagnosis was made and 17-27 years after the first demonstration of metastases. One woman had multiple chondromatous hamartomas of the lung. Operations were performed when the patients had symptoms and during periods of no symptoms, as directed by the second-look principle. One patient had 10 operations. None of the patients received adjuvant therapy. All three women have given birth to healthy children after metastases were diagnosed. Three of the primary tumors were large (10-20 cm) and multinodular, features that have been associated with unfavorable prognosis. The four primary tumors had a similar light microscopic appearance, characterized by moderate cell and nuclear pleomorphism and low mitotic activity, 0.03-0.1/mm2. Ultrastructurally, a network of intermediate filaments was found within the cytoplasm of the tumor cells corresponding to the immunohistochemical positivity for vimentin. The immunohistochemical findings (negative immunoreaction for desmin and alpha smooth-muscle actin) and the ultrastructural analysis produced no evidence of the production of smooth-muscle cell myofilaments. However, there were tumor cells with an abundance of mitochondria and a paucity of filaments, features that may be characteristic of epithelioid leiomyomatous tumors. In addition, immunohistochemical negativity for cytokeratins, epithelial membrane antigen, S-100 protein, neuron-specific enolase, and chromogranin militate against an epithelial or neuroectodermal cell differentiation. CONCLUSIONS. An awareness of this type of gastric leiomyosarcoma in children and young adults is of importance in making correct assessments of prognosis and choosing an active therapeutic approach. The biologic background to the clinical behavior of these metastasizing tumors remains an enigma. Additional studies are needed to elucidate the biology of these tumors.