Clear Cell Odontogenic Carcinoma—A Rare Case Report

Abstract

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic tumour with female predilection occurring in the anterior region of the mandible with peak age incidence of 5th and 7th decade of life. Here we report a case occurred in the posterior mandible of a 42 year old male patient which highlights the clinicopathologic features of CCOC that were confirmed by histopathologic examination. We add up yet another case of CCOC to the published literature.

Introduction

Odontogenic neoplasms composed of predominantly clear cells are quite unusual and represent a diagnostic challenge. Originally thought of as benign tumors, these neoplasms have been referred to as clear cell odontogenic tumors or clear cell ameloblastomas. However, on the basis of their aggressive behavior, predilection for local recurrence, evidence of distant metastasis, and histologically distinct features, these tumors are now considered malignant. They have been subsequently classified as clear cell odontogenic carcinomas (CCOCs) [1].

Clear cell odontogenic carcinoma (CCOC) is an unusual intraosseous tumour that tends to occur in the anterior region of the mandible of older adults with a predilection for women. It is potentially aggressive with loco-regional and distant metastasis. Primary Odontogenic Carcinomas are rare. Approximately around 47 cases have been reported in the literature [2]. We describe a case which occurred in the posterior mandible of a 42 year old male patient.

This article highlights the clinicopathologic features of CCOC that were confirmed by histopathologic examination. The aggressive potential of this neoplasm is well documented. The limited number of reported cases precludes a definitive assessment of prognostic factors or efficacy of therapy in CCOC.

Case Report

A 42 year old male reported with a swelling in the left mandibular premolar, molar region of 3 months duration (Fig. 1a, b).

Fig. 1.

a Preoperative patient photograph showing swelling in left mandibular region. b Preoperative patient photograph showing swelling in left mandibular region—lateral view

Patient gave a history of gradual increase in swelling of the mandible with no history of trauma. Initially the swelling was small to start with and then increased to the present size within 3 months. This was the first episode of such a swelling and family history was negative. The systemic review was also non-contributory.

Extra oral examination showed a 6.0 × 4.2 cm firm to bony hard painless swelling extending from parasymphysis to the angle of left mandible. Lymph nodes were not palpable.

Intraoral examination revealed a pink, bulging fleshy mass obliterating the vestibule extending from first premolar to distal of second molar on same side. On palpation the swelling was firm to hard in consistency with no local rise in temperature and parasthesia of the lower lip. Intra lesional aspiration was negative. The related teeth were showing grade II mobility. With the above features a clinical differential diagnosis of Ameloblastoma variants and central giant cell granuloma was given.

Computed tomographic examination of the lesion demonstrated irregular margins extending from first premolar to distal to second molar of the left side of the mandible. There was marked destruction of the cortical plates showing sun ray appearance. Based on the foregoing an impression of Osteosarcoma of the left mandible was made (Fig. 2). Abdominal ultrasound of the kidneys, liver and spleen were essentially normal. Hematological and biochemical parameters were within normal limits.

Fig. 2.

CT scan showing irregular margins, marked destruction showing sun ray appearance of mandible

An incisional biopsy of the lesion was submitted for histopathologic evaluation. Histological examination of the tissue showed a neoplasm composed of epithelial cells arranged in irregular nests and sheets of cells separated by fibrous connective tissue.

No evidence of ameloblastic differentiation was observed, majority of the cells were isomorphic with well defined outlines. Prominent atypia and mitotic figures were absent. The tumor cells were negative for alcian blue but positive for glycogen.

Histologically diagnosed as clear cell odontogenic carcinoma and the patient were then subjected to enbloc resection of tumour mass.(Fig. 3) The reconstruction was done by bone plate and covered with major flap (Fig. 4). The healing was uneventful and then the patient was referred for radiotherapy (Fig. 5).

Fig. 3.

Picture taken during surgery, the lesion extending from left first premolar to ramus of the mandible

Fig. 4.

Photograph showing reconstruction of mandible by bone plate after excision of lesion

Fig. 5.

Post operative photograph

Post operative excisional specimen (Fig. 6) histological examination showed tumour morphology similar to incisional biopsy. The tumour islands showed cells with bimorphic morphology, containing both clear cells and more hyperchromatic appearing polygonal cells and they exhibited cytoplasmic eosinophilia (Fig. 7).

Fig. 6.

Post surgical specimen

Fig. 7.

Photomicrograph showing bimorphic cells with clear and hyperchromatic cells (H&E, 40×)

Cellular pleomorphism and mitotic figures were rarely seen, but when seen they were in polygonal population (Fig. 8). There was no encapsulation and the tumour cells were invading the medullary bone and are separated by zones of mature, fibrous and partly hyalinized connective tissue stroma (Fig. 9).

Fig. 8.

Photomicrograph showing rare mitotic figures in polygonal cells (H&E. 10×)

Fig. 9.

Photomicrograph showing epithelial cells separated by mature, hyalinized connective tissue stroma and tumour cells invading medullary bone (H&E, 10×)

Clear cell mucoepidermoid carcinoma, clear cell acinic cell carcinoma, clear cell oncocytoma, epithelio—myoepithelial carcinoma, clear cell variant of CEOT and metastatic renal clear cell carcinoma were considered in differential diagnosis.

The patient was lost of follow up only to reappear after 8 months and at the time he had no sign of local or regional spread.

Discussion

Clear cell odontogenic carcinoma was first described by Hansen et al. in 1985 [3] as clear cell odontogenic tumour. This neoplasm was initially thought to be devoid of malignant potential and classified as benign [4]. Subsequently, similar cases showing aggressive behavior, recurrent behavior and metastatic spread were reported and then designated as clear cell odontogenic carcinoma (CCOC) by Bang et al. in 1989 [5, 6].

CCOC is a rare odontogenic tumour with female predilection and peak age incidence in the 5th and 7th decade of life. The age was consistent with the demographic data of our patient.

Published literature showed that the anterior portions of the jaws especially the mandible of females is most frequently affected [4, 7]. This is contrast with the case being in the male patient and occurring in the posterior mandible.

Histopathologically, CCOCs may show one or more of three architectural patterns: biphasic, monophasic, and ameloblastomatous. The most common biphasic pattern of tumor growth comprises of nests of cells with clear cytoplasm admixed with cells containing eosinophilic cytoplasm. The monophasic pattern comprises only of clear cells, while the ameloblastomatous pattern resembles the growth pattern of ameloblastoma with nests of cells showing central cystic change and squamous differentiation, and peripheral nuclear palisading with reverse polarity [8]. Our case is of the first type which is the commonest of all with biphasic pattern of tumour growth.

Braunshtein et al. [9] reviewed the literature and found 27 cases of CCOC reported worldwide that showed a high rate of recurrence (50%) and metastasis (33%). Kumar et al. [7] also documented a case which metastasized to the 5th lumber vertebra and hip 3 years after the initial diagnosis, thus emphasizing the need for long-term follow up. Local recurrence is a common finding and cytologic atypia appears to worsen with recurrent lesions. Even additional special staining for mucin is recommended to rule out mucoepidermoid carcinoma. Furthermore, CCOC can be distinguished from the clear cell variant of calcifying epithelial odontogenic tumor because it lacks the characteristic calcification and amyloid deposition [10].

There were no definite universal treatment protocols for CCOC in the literature probably due to the recurrences and/or metastasis that have been recorded following aggressive surgery. Factors such as size of the lesion, soft tissue involvement, lymph node metastasis and most importantly, the presence or absence of positive surgical margins should be considered when developing the treatment strategy. Hence, CCOC should be regarded as a low-grade malignancy with capacity for sinister biologic behavior. Treatment should be by wide surgical resection with at least 1 cm of tumor-free margins. In addition, elective neck dissection and adjuvant radiotherapy is suggested.