Multifocal Large Cystic Liver Metastasis of a Sinonasal Tract Ameloblastoma: An Unusual Clinical Presentation

Abstract

Ameloblastoma is a slowly growing, locally invasive tumor of odontogenic epithelial origin. On rare occasion, a well-differentiated ameloblastoma may metastasize. Recently, we encountered a unique case of metastatic ameloblastoma in the liver in a 48-yearold woman. Preoperative radiographic study revealed multiple cystic lesions in the liver, 6 of which were confirmed intraoperatively. Macroscopic examination of the resected tumors revealed well-circumscribed, encapsulated cystic lesions. Sections from the tumors demonstrated solid interlocking islands with peripheral palisading of "basaloid cells" and squamous differentiation of centrally located cells. The cytology of these tumors was bland and the mitotic activity was low. Immunohistochemistry showed immunoreactivity for CK5/6 and p63, immunoreactivity for CD10 in the peripherally palisading cells and immunoreactivity for CK19 in the centrally located cells. The resected liver cystic tumors were originally diagnosed as "low-grade cystic ameloblastoma-like tumor in the liver" and suggested a possibility of metastasis. The patient was doing well clinically after the resection of her liver lesions. However, CT scan of the head and neck region at another hospital one year later showed an enhancing, expansile, well circumscribed mass in the right nasal cavity. Biopsy and resection of the nasal mass revealed an ameloblastoma invading the maxillary bone. The patient is doing well 2 months after her nasal surgery. To our knowledge, this is the first case of ameloblastoma manifested as liver metastases prior to the identification of a sinonasal primary.