The controversy of surgical seeding or metastasis of a recurrent ameloblastoma is discussed in this paper, where we present a case with a history of 28 years since primary diagnosis including several tumor removals and reconstructive events. 23 years after primary diagnosis, we removed a metastasis from the neck with similar histological features as the primary tumor and the following recurrences of the mandible. We argue that the removed tumor in the neck most possibly has its origin in surgical seeding of cells during earlier resection and reconstruction and not by common ways of metastasis. The seeding of tumor cells during tumor surgery and metastasis rate of malignant ameloblastoma is discussed and the literature in this area is reviewed in the paper.
Ameloblastoma is an uncommon disease that represents 1% of all cysts and tumors diagnosed in the jaws [1,2]. These benign slow-growing aggressive neoplasms show a distressing tendency to exhibit locally aggressive behavior and local recurrence in 50% to 72% of cases [3,4]. Their potential for rare metastasis seems to be poorly understood [5]. Furthermore, tumor seeding during surgery leading to recurrence of the tumor appears to be rarely considered [6]. Hence, in this study we report a case of a 67-year-old female with a recurrent ameloblastoma, which presented in the submandibular region. Histology revealed an ameloblastoma with the same obviously benign growth pattern as in the primary lesion that before had presented in all the preceding surgeries of the jaw.
Although ameloblastoma of the jaws is most often considered by clinicians to be a benign tumor, some of these can be reclassified as malignant when metastases occur [7]. The 2005 World Health Organization (WHO) Classification of Odontogenic Tumors places metastasizing ameloblastoma under the general grouping of odontogenic carcinomas, along with ameloblastic carcinoma [8]. The typical WHO description of a metastasizing (malignant) ameloblastoma is an ameloblastoma that metastasizes in spite of a benign histological appearance [9]. This must be clearly distinguished from the ameloblastic carcinoma (primary type) which is characterized by histological malignant features in both the primary and metastatic sites [7,10].
A review of the literature regarding ameloblastoma indicates that there has been confusion about the terminology which has led to falsification of the frequency of metastasizing (malignant) ameloblastoma compared to ameloblastic carcinoma. Recent literature portends that the incidence of metastasizing (malignant) ameloblastoma has been overestimated while the incidence of ameloblastic carcinoma has been undervalued [11].
2. CASE REPORT
In the year 2007 a 67-year-old female was referred to the Department of Oral & Maxillofacial Surgery, Uppsala University Hospital, for revision of a failed radial forearm flap reconstruction performed 3 years earlier after resection of an ameloblastoma. The patient had underwent numerous operations, in the years 1984, 1989, 1995, 2001, and in 2004 a hemimandibulectomy and reconstruction plate plus radial forearm-flap had been performed.
While planning a reconstruction of the defect with a vascularised fibular osteoseptocutaneous flap graft, a medical checkup revealed a distinctly enlarged goitre, which considerably displaced the trachea and thus had to be treated primarily. After the thyroidectomy had been performed and the patient had recovered from this intervention, the patient underwent the reconstruction of the mandible in January 2008. During this operation a tumorous nodule in the submandibular/neck area was recognized and excised (Figures 1-4). The histological examination of the sections showed structures of a recurrent ameloblastoma with the typical architecture—islands of epithelium distributed in a fibrous connective tissue stroma.
Retrospectively the micromorphology of the tumor tissue in the biopsies and surgical specimen remained essentially identical over time (Figures 5-8). The tumor presented a follicular pattern with islands and sheaths of
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