Ossifying malignant mixed epithelial and stromal tumor of the liver: a case report of a previously undescribed tumor.

Background: Malignant mixed tumors of the liver in adults are rare. To the authors' knowledge, twenty-four cases of primary malignant mixed hepatic tumors have been reported in the literature since the first description by Walter in 1896. Many of the previously reported cases are now considered mixed hepatoblastoma, primary hepatocellular carcinomas with focal sarcomatous metaplasia, or epithelioid hemangioendothelioma.

Methods: Clinical, radiologic, histologic and immunohistochemic methods were used to characterize an unusual example of a mixed malignant tumor of the adult liver that the authors descriptively refer to as "ossifying malignant mixed epithelial and stromal tumor" of the liver.

Results: In contrast to previously reported cases, the tumor in question was morphologically distinct. It was composed of three distinct neoplastic phenotypes: malignant spindle cells, with adenocarcinomatous differentiation, and extensive osteoid formation. The tumor was treated by partial hepatectomy. The patient was alive 8 years postoperatively as of December 2001. The distinctive combination of morphologic features and prolonged survival are much different from previously reported cases of mixed malignant hepatic tumors, which were typically rapidly fatal.

Conclusions: The authors believe that the clinical and pathologic features of this patient's tumor are sufficiently distinctive to exclude it from the well-established categories of hepatic neoplasms. Histologically, the authors suggest the descriptive name "ossifying malignant mixed epithelial and stromal tumor of the liver" as a preliminary description for this tumor until the origin and relationship to other hepatic neoplasms are further characterized.