PhiliPPine Journal of otolaryngology-head and neck Surgery 67 PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 30 no. 2 July – december 2015 UNDER THE MICROSCOPE A 27-year-old man presented with an 8 cm diameter left maxillary mass and an enlarged cervical lymph node at levels II to III. There was a reported history of a previous unspecified operation on the maxillary mass which had yielded a diagnosis of ameloblastoma. Total maxillectomy with modified radical neck dissection was subsequently performed. Microscopic examination of the maxillary mass shows epithelial islands and cords in a fibro- collagenous stroma. (Figure 1) The islands and cords are lined in the periphery by palisaded columnar cells with regular ovoid nuclei exhibiting reverse polarization. The nuclei are uniform with dispersed chromatin and no significant atypia. Towards the center of these islands are loosely arranged spindly to stellate cells (“stellate reticulum”). (Figure 2) Microscopic examination of the largest submitted lymph node shows an epithelial neoplasm with identical histologic features as the maxillary mass and a residual rim of lymphoid tissue at the periphery enclosed by the nodal capsule. (Figure 3) Similarly, there is neither atypia nor pleomorphism and only a few typical mitotic figures are seen in the nodal tumor. (Figure 4) These features support the diagnosis of a metastasizing ameloblastoma (MA). Metastasizing ameloblastoma is rare with only about 70 reported cases.1-5 Both the gnathic primary tumor and the metastatic foci have typical morphologies of a benign ameloblastoma with bland nuclei and absent to rare mitosis.6,7 There are no morphologic criteria that can predict this metastatic behavior. Thus, this diagnosis can only be made in retrospect upon the appearance of metastasis in a gnathic tumor that would otherwise have been diagnosed as a usual benign Metastasizing Ameloblastoma Correspondence: Dr. Jose M. Carnate, Jr. Department of Pathology College of Medicine, University of the Philippines Manila 547 Pedro Gil St. Ermita, Manila 1000 Philippines Phone (632) 526 4450 Telefax (632) 400 3638 Email: jmcjpath@gmail.com Reprints will not be available from the authors. The authors declared that this represents original material that is not being considered for publication or has not been published or accepted for publication elsewhere, in full or in part, in print or electronic media; that the manuscript has been read and approved by the authors, that the requirements for authorship have been met by the authors, and that the authors believe that the manuscript represents honest work. Disclosures: The authors signed disclosures that there are no financial or other (including personal) relationships, intellectual passion, political or religious beliefs, and institutional affiliations that might lead to a conflict of interest. Philipp J Otolaryngol Head Neck Surg 2015; 30 (2): 67-68 c Philippine Society of Otolaryngology – Head and Neck Surgery, Inc. Jenny Maureen L. Atun, MD1 Jose M. Carnate, Jr., MD2 1Department of Laboratories Philippine General Hospital University of the Philippines Manila 2Department of Pathology College of Medicine University of the Philippines Manila Figure 1. Section from the maxillary mass showing islands and cords of epithelial cells set in a fibro-collagenous stroma (Hematoxylin and Eosin, 40x magnification) (Hematoxylin and Eosin, 40x) PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 30 no. 2 July – december 2015 UNDER THE MICROSCOPE 68 PhiliPPine Journal of otolaryngology-head and neck Surgery REFERENCES Lin Y, He JF, Li ZY, Liu JH. Ameloblastoma with varied sites of metastasis: Report 1. of two cases and literature review. J Craniomaxillofac Surg 2014 Jul; 42(5): e301- e304. Gilijamse M, Leemans CR, Winters HAH, Schulten EAJM, van der Waal I. 2. Metastasizing ameloblastoma. Int J Oral Maxillofac Surg. 2007 May; 36 (5): 462- 464. Kim Y, Choi SW, Lee JH, Ahn KM. A single cervical lymph node metastasis of 3. malignant ameloblastoma. J Craniomaxillofac Surg 2014 Dec; 42 (8): 2035-2040. Jayaraj G, Sherlin HJ, Ramani P, Premkumar P, Natesan A, Ramasubramanian A, 4. Jagannathan N. Metastasizing ameloblastoma – a perennial pathology enigma? Report of a case and review of literature. J Craniomaxillofacial Surg 2014 Sep; 42 (6): 772-779. Dissanayake RKG, Jayasooriya PR, Siriwardena DJL, Tilakarante WM. Review of 5. metastasizing (malignant) ameloblastoma (METAM): pattern of metastasis and treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011 Jun; 111 (6):734- 741. Neville BW, Damm DD, Allen CM. Chapter 10: Odontogenic Cysts and Tumors. 6. In: Gnepp, DR. (editor) Diagnostic Surgical Pathology of the Head and Neck. 2nd edition. 2009; Philadelphia: Saunders Elsevier. Pp. 802-810. Sciubba JJ, Eversole LR, Slootweg PJ. Odontogenic/ameloblastic carcinomas. In: 7. Barnes, L., Eveson, JW., Reichart, P. and Sidransky, D. World Health Organization Classification of Tumours. Pathology and Genetics of Head and Neck Tumors. 2005; Lyon: IARC Press. P. 287. Ahlem B, Wided A, Amani L, Nadia L, Amira A, Faten F. Study of Ki67 and CD10 8. expression as predictive factors of recurrence of ameloblastoma. Eur Ann Otorhinolaryngol Head Neck Dis 2015 Sep 16. pii: S1879-7296(15)00115-5. doi: 10.1016/j.anorl.2015.08.016. [Epub ahead of print]. Abdil-Aziz A, Amin MM. EGFR, CD10 and proliferation marker Ki67 expression in 9. ameloblastoma: possible role in local recurrence. Diagn Pathol 2012 Feb; 7:14 doi: 10.1186/1746-1596-7-14. ameloblastoma.1-7 Suggested risk factors include rapid tumor growth, large primary tumor, delay in treatment, mandibular site, prior radiotherapy and chemotherapy.4,5 However, what is most consistent in the literature is the history of multiple recurrences and multiple surgical interventions.1,4,5 The differential diagnosis is an ameloblastic carcinoma (AC). Both MA and AC are considered as the malignant counterparts of ameloblastoma.7 However AC is characterized by the presence of the usual cytologic features of a malignant neoplasm such as nuclear pleomorphism, hyperchromasia and brisk mitotic activilty – features that are lacking in MA.6,7 The literature on metastasizing ameloblastoma lists the lungs (70 to 88% of cases) and the cervical lymph nodes (15- 37.8% of cases) as the most common sites of metastasis.1-5 Increased Ki-67 labeling and CD10 immunoreactivity have been reported to have significant correlation with recurrence.8,9 Whether these observations also apply to the risk of metastasis is not known due to the rarity of cases and hence the small subject populations of these studies. As the risk of metastasis cannot be predicted by morphology, long-term follow-up appears prudent in all cases of ameloblastoma especially if characterized by recurrences and prior surgical interventions. Figure 2. Peripheral palisaded columnar cells with reversed nuclear polarization (arrow) and central stellate reticulum (circle). The nuclei do not exhibit pleomorphism. (Hematoxylin and Eosin, 400x magnification) (Hematoxylin and Eosin, 400x) Figure 3. Section from the cervical lymph node containing metastatic tumor. There is residual nodal lymphoid tissue (arrow). The lymph node capsule is also shown (circle). (Hematoxylin and Eosin, 100x magnification) (Hematoxylin and Eosin, 100x) Figure 4. The tumor islands in the lymph node show a similar bland cytology. (Hematoxylin and Eosin, 400x magnification) (Hematoxylin and Eosin, 400x)