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Year : 2012  |  Volume : 55  |  Issue : 4  |  Page : 591-592
Preoperative cytological diagnosis of ameloblastoma involving the maxilla


1 Department of Pathology, Government Medical College, Kottayam, Kerala, India
2 Department of Orofacial and Maxillary Surgery, Government Dental College, Kottayam, Kerala, India

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Date of Web Publication4-Mar-2013
 

How to cite this article:
Thambi R, Subitha K, Mohan S, Letha V. Preoperative cytological diagnosis of ameloblastoma involving the maxilla. Indian J Pathol Microbiol 2012;55:591-2

How to cite this URL:
Thambi R, Subitha K, Mohan S, Letha V. Preoperative cytological diagnosis of ameloblastoma involving the maxilla. Indian J Pathol Microbiol [serial online] 2012 [cited 2020 Sep 20];55:591-2. Available from: http://www.ijpmonline.org/text.asp?2012/55/4/591/107839



   Case Report Top


A 50 year-old man presented to our hospital with a painless mass in the right alveolar sulcus, of one year duration, which was slowly increasing in size. On examination, it was a hard bony mass with normal overlying mucosa. No draining sinus or lymphadenopathy was noted. Computed tomography (CT) scan showed a soft tissue mass measuring 5 × 3 × 4 cm filling the maxillary antrum and reaching up to the ethmoid sinus and lateral wall of the nose. An impacted root of a molar tooth was seen on the lower aspect [Figure 1]a. Radiology was suggestive of a benign expansile lesion-odontogenic cyst. Fine needle aspiration cytology (FNAC) was advised as the dental surgeon wanted to rule out malignancy.
Figure 1: (a) CT scan showing a soft tissue lesion filling Rt maxillary antrum 5 x 3 x 3 cm extending up to ethmoid sinus and lateral wall of nose.(b) Photomicrograph showing sheet of squamous and basaloid cells (pap stain, ×400) (c) Nuclei with peripheral palisading and moulding. (d) Spindle cells and fragments of stroma. (pap stain, ×400)

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After obtaining informed consent, the patient was taken for FNAC. Repeated aspirations yielded blood stained fluidy material. Smears were cellular and showed sheets of basaloid cells with peripheral pallisading of nuclei [Figure 1]b, c. Cells had scanty cytoplasm and round/oval nuclei with moulding. Occasional sheets of squamous cells, spindle cell stromal fragments and scattered macrophages were also seen [Figure 1]d. No inflammation, malignant cells or atypical mitosis were noted. A diagnosis of ameloblastoma was made on cytology. So, the surgeon proceeded with maxillectomy [Figure 2]a. Histopathological examination was suggestive of follicular ameloblastoma [Figure 2]b-d. There was adequate tumour clearance. The patient is on follow up for the last one year and is doing well.
Figure 2: (a) Gross specimen showing the neoplasm with solid and cystic areas. (b,c,d) Histopathology sections showing sheets of tumour cells with peripheral pallisading and stellate stroma, suggestive of follicular ameloblastoma. (Hematoxylin and Eosin, ×400)

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   Discussion Top


Ameloblastoma is a rare odontogenic tumor that develops from the odontogenic epithelium, its derivatives or remnants and rarely from a dentigerous cyst. It represents approximately 1% of oral tumors and 80% occur in the mandible. Ameloblastoma occurs in the 3 rd to 4 th decade of life. Maxillary ameloblastomas are seen a decade later. [1],[2] They are locally aggressive tumors that spread through the marrow spaces with pseudopod formation. There is no associated trabecular bone resorption. Therefore, the tumor margins are less evident on radiology and grossly during surgery. [1],[2] This may be the reason for the increased recurrence rate for these tumors. Recurrent ameloblastomas behave more aggressively with risk for metastasis. A definite diagnosis before the surgery is therefore essential, and FNAC is a very useful investigation. Needle aspiration is easy in ameloblastoma because of bone lysis and destruction. In an appropriate clinical and radiological setting, FNAC is an effective diagnostic tool.

Five to twenty per cent cases of ameloblastomas involve the maxilla with a majority arising in the molar region. [2] Our case was involving the maxilla with extension into the maxillary antrum. Primary ameloblastoma (extragnathic) of the paranasal sinuses with a better prognosis has to be differentiated from maxillary ameloblastoma extending to the sinuses, as in our case. [3] Maxillary ameloblastoma shows slow growth and has a tendency to remain asymptomatic for long. This, along with cancellous nature of maxilla leads to extensive tumor spread and involvement of sinuses, orbit and cranial cavity at presentation. [1],[2]

The cytological findings include presence of basaloid cells with peripheral pallisading of nuclei; squamous, stellate and spindly cells are diagnostic. [4],[5] Anaplasia, mitosis and necrosis are suggestive of malignancy in ameloblastoma. [5] Various histological subtypes - follicular, acanthomatous, plexiform, granular, clear cell and desmoplastic are recognized. The differential diagnoses are odontogenic cysts, salivary gland tumors and squamous cell carcinoma metastasis. [4] Fluidy material showing macrophages and squamous cells mimic other benign odontogenic cysts. Atypia of the squamous component in ameloblastoma may mimic squamous cell carcinoma metastasis. Mucin laden cells, squamous component and basaloid cells may suggest tumors of salivary gland origin. Deligent search for squamous, stellate and basaloid cells along with nuclear pallisading will help in making the right diagnosis. Radical surgery rather than curetting or enucleation is required to avoid recurrence in ameloblastoma.

This case is unique as ameloblastoma is rare in the maxilla and there was involvement of the paranasal sinuses. Cytology is less popular for the diagnosis of odontogenic tumors, possibly due lack of awareness. But, ameloblastomas on aspiration give a good cell yield and have distinct cytological features. In the appropriate clinical and radiological setting, it is almost as effective as histopathology. FNAC is a minimally invasive, safe, fast and inexpensive method for diagnosing odontogenic tumors, which ensures that patients receive proper treatment and avoid recurrence. This case highlights the sufficiently distinctive cytological features of ameloblastomas, which make their diagnosis by FNAC possible.

 
   References Top

1.Iordanidis S, Makos C, Dimitrakopoulos J, Kariki H. Ameloblastoma of the maxilla. Case report. Aust Dent J 1999;44:51-5.  Back to cited text no. 1
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2.Ajike SO, Omisakin OO, Adebayo ET, Chom ND, Samaila MA. Ameloblastoma: An enigma for the surgeon. Niger Med J 2009;50:47-51.  Back to cited text no. 2
  Medknow Journal  
3.Shahidi SH, Bronoosh P, Daneshbod Y. Follicular ameloblastoma presenting as a sinonasal tumor. Iran Red Crescent Med J 2012;14:113-6.  Back to cited text no. 3
[PUBMED]    
4.Gunhan O. Fine needle aspiration cytology of ameloblastoma. A report of 10 cases. Acta Cytol 1996;40:967-9.  Back to cited text no. 4
[PUBMED]    
5.Bisht S, Kotwal SA, Gupta P, Dawar R. Role of fine needle aspiration in preoperative diagnosis of ameloblastoma. Indian J Cancer 2009;46:348-50.  Back to cited text no. 5
[PUBMED]  Medknow Journal  

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Correspondence Address:
Renu Thambi
Assistant Professor, Department of Pathology, Govt. Medical College Kottayam, 686 008, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.107839

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