Oral Maxillofac Surg DOI 10.1007/s10006-015-0483-8
CASE REPORT
Central mucoepidermoid carcinoma of the anterior region of the mandible: report of an unusual case and review of the literature Nikos Kechagias & Aris Ntomouchtsis & Alexandra Mavrodi & Barbara Christoforidou & Antonis Tsekos & Kostas Vahtsevanos
Received: 5 November 2014 / Accepted: 5 January 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Introduction Central mucoepidermoid carcinoma is a rare lesion, whose exact pathogenesis is still not fully understood. Generally, it is more frequently encountered in the mandible than in the maxilla and in the posterior than in the anterior aspect of the jaws. Cases of central mucoepidermoid carcinomas are rarely mentioned in the literature, and therefore, additional information concerning this type of lesion is needed. Case report In the present paper, we report an extremely unusual case of a central mucoepidermoid carcinoma in the anterior region of the mandible of a 37-year-old female patient. The diagnosis and the surgical management of the tumor along with the reconstructive techniques utilized to restore the mandible and a 6-year follow-up are discussed. Discussion Central mucoepidermoid carcinoma is an unusual tumor of the jaws, especially in the anterior region. It is only locally aggressive and has most frequently a good prognosis if treated with wide surgical excision.
N. Kechagias Division of Oral & Maxillofacial Surgery, Clinic St. Loukas, Thessaloniki, Greece A. Ntomouchtsis Private Praxis, Luzern, Switzerland A. Mavrodi (*) : K. Vahtsevanos Department of Oral and Maxillofacial Surgery, Aristotle University of Thessaloniki, Thessaloniki, Greece e-mail: [email protected] B. Christoforidou Department of Histopathology, Theagenion Cancer Hospital of Thessaloniki, Thessaloniki, Greece A. Tsekos Oral & Maxillofacial Department, Army General Hospital of Thessaloniki, Thessaloniki, Greece
Keywords Central mucoepidermoid carcinoma . Anterior . Mandible . Diagnosis . Surgical management . Follow up
Introduction Mucoepidermoid carcinoma (MEC) was initially described as an entity in 1945 by Steward et al. [1]. Histologically, it is characterized by three main cell types, mucin-producing, epithelial, and intermediate cells [2, 3], and it constitutes 5–10 % of all salivary gland tumors affecting most commonly the parotid gland (89.6 %) and less frequently the submandibular (8.4 %) and sublingual salivary gland (0.4 %) [4]. Lepp was the first to report an intraosseous mucoepidermoid carcinoma located in the mandible of a 66-year-old woman [5]. Ectopic salivary gland tissue has also been detected in even more distant parts of the body, like the thyroid, the hypophysis, the mastoid bone, the middle ear, and the skin [6, 7]. Nonetheless, central mucoepidermoid carcinoma (CMEC) is far more frequent in the mandible and in the maxilla than in other bones, due to the close relationship of the mesenchymal to the ectodermic tissue in these particular bones, which may result in epithelial tissue entrapment during bone growth [8]. Despite the fact that MEC is the most frequent malignant salivary gland tumor, CMEC as a primary intraosseous bony lesion is much more rare, with an incidence of 2–4.3 % of all MECs reported [9]. Regarding its origin, several theories have been proposed; however, its exact pathogenesis is still uncertain and not fully understood. CMEC affects in a higher ratio females than males [6, 10–12]. Ιt has been observed in all age groups but is more common in the mandible during the 4th and 5th decades [4, 10]. Furthermore, CMEC is more frequently encountered in the mandible than in the maxilla [13, 14].
Oral Maxillofac Surg
In this paper, we report a case of a CMEC in the anterior region of the mandible of a 37-year-old female patient. Surgical management of tumor resection and bone defect reconstruction along with special intraoperative imaging techniques, plus a 6-year follow-up period are presented. Case report A 37-year-old female patient was referred to the Department of Maxillofacial Surgical Oncology Theagenio Cancer Hospital with a chief complaint of pain in the anterior teeth region of the mandible, which was present for 6 months prior to seeking medical attention. Clinical examination revealed a bony hard swelling involving the anterior region of the mandible from the right second premolar to the left first premolar. The overlying mucosa was intact with no signs of infection, while cervical lymphadenopathy was absent. There was no significant past medical history, except for mitral valve prolapse, and the patient reported no extraoral or intraoral trauma in the region and no former oral surgical interventions. Panoramic radiograph showed a multilocular, expansile osteolytic lesion extending from the distal aspect of the right second premolar to the mesial aspect of the left second premolar (Fig. 1). A computed tomography scan (CT) confirmed the presence of the osteolytic lesion and displayed expanded lingual and buccal cortices with some signs of cortical erosion (Fig. 2). No abnormalities were observed regarding cervical lymph nodes or soft tissues and organs of the head and neck region. With a provisional clinical diagnosis of an ameloblastoma, an incisional biopsy was performed under local anesthesia. Histopathological examination showed cystic spaces lined by slightly thickened cuboidal, epidermoid, columnar and mucous epithelial cells adjacent to lameral bone. The simultaneous presence of mucous and squamoid epithelium
Fig. 1 Panoramic radiograph showing a multilocular osteolytic lesion extending from the distal aspect of the right second premolar to the mesial aspect of the left second premolar
Fig. 2 Axial CT image depicting an extensive osteolytic lesion. Expanded lingual and buccal cortices with some signs of cortical erosion are traced
suggested a mucoepidermoid carcinoma. However, clear evidence of infiltration was not present in the otherwise restricted biopsy specimen (Fig. 3). Since biopsy results were inconclusive but suggested a diagnosis of a mucoepidermoid carcinoma, excision of the whole mass was planned out. Segmental mandibulectomy extending from the distal aspect of the right first molar to the distal aspect of the left second molar, involving all of the
Fig. 3 Photomicrograph of the biopsy specimen showing cystic spaces lined by slightly thickened cuboidal, epidermoid, columnar, and mucous epithelial cells (HEX200)
Oral Maxillofac Surg
thirteen mandibular teeth of the patient was performed. Additionally, bilateral selective neck dissection (levels I–III) was carried out. The gross specimen measured 7.5×5.5×4 cm and involved thirteen teeth. Macroscopically, an intraosseous polycystic lobular formation was observed with a largest diameter of 6 cm. The surgical margins of the specimen were additionally evaluated intraoperatively using digital mammograph imaging according to the method proposed by Ntomouchtsis et al. (Fig. 4) [15]. Digital images of the mandible indicated clinically complete excision. Due to the large dimensions and the location of the mandibular defect, a reconstruction of the mandible was necessary in order to achieve functional and cosmetic restoration. Specifically, reconstruction with a free rib graft and plate osteosynthesis was performed. In order to achieve soft tissue cover of the graft, a bilateral naso-labial flap was utilized. Histopathological examination revealed that the neoplasm was mainly consisted of numerous cystic spaces lined by columnar, mucous, intermediate, and epidermoid epithelial cells. In some places, there were more solid areas with mild atypia among mature appearing bony trabeculae. Based on these morphologic criteria, combined with the radiologic ones (osteolytic lesion with signs of cortical erosion), the diagnosis of a central mucoepidermoid carcinoma of low grade malignancy was confirmed (Fig. 5). Moreover, only traces of reactive lemphadenitis were found, and no lymph nodes infiltrated by tumor in the neck dissections specimens were discovered. Since the resection margins were negative for malignancy, the patient did not undergo any other therapy. Magnetic resonance imaging (MRI) showed no signs of recurrence 7 months after the surgery (Fig. 6). Fifteen months after the surgery, the patient remained disease-free and sought further medical attention in order to restore her chewing ability. Since there was a lack of sufficient bone support owing to the reduced height of the rib graft, a microvascular osteocutaneous fibula flap was utilized to restore the missing bone height. Secondary operations in terms of implant
Fig. 5 a Photomicrograph showing multiple cystic spaces lined by columnar, mucous, intermediate, and epidermoid epithelial cells along with mature appearing bony trabeculae (HEX100). b More solid areas with mild atypia (HEX200)
insertion and eventual dental rehabilitation were performed (Fig. 7). The patient is currently disease-free and satisfied with her functional and cosmetic status 6 years after the excision of the tumor.
Discussion
Fig. 4 Intraoperative evaluation of the surgical margins of the specimen using digital mammograph imaging
CMC is more common in the mandible than in the maxilla and in the posterior than in the anterior aspect of the jaws [6, 9]. Specifically, only 3 % of all discovered CMECs are encountered in the anterior mandible and maxilla [12]. Browand and Waldron reported three cases of an anteriorly located CMEC in the mandible, out of which only one crossed the midline extending from the left to the right canine region [10]. Grubka et al. described a case of a CMEC located in the right anterior mandible [1], whereas Tucci et al. reported a more extensive CMEC in the anterior mandibular region between the molars
Oral Maxillofac Surg
Fig. 6 MRI image indicating complete excision of the lesion and no signs of recurrence
[16]. Our case is a highly rare finding constituting an extremely unusual CMEC of the anterior part of the mandible crossing the midline and extending from the left second premolar to the right second premolar. As regards CMEC’s histogenesis, although multiple theories have been suggested, no hypothesis can sufficiently explain the pathogenesis of all these lesions. The most possible origins are as follows: (a) metaplasia of mucus-secreting cells from the lining epithelium of dentigerous cysts, (b) retromolar mucous gland tissue that has been entrapped and later underwent neoplastic transformation, and (c) embryologically entrapped submandibular and sublingual salivary gland tissue within the mandible during development. As proposed, other
Fig. 7 Panoramic radiograph 4 years after the surgery showing bone structures along with implants and dental rehabilitation
possible sources of origin of CMEC may also be as follows: metaplasia and invasion from the maxillary sinus epithelium, odontogenic remnants of the dental lamina or iatrogenic entrapment of minor salivary glands (e.g., chronic osteomyelitis and sinusitis) [10, 17, 18]. Clinically, patient’s main symptoms when affected by CMEC include pain, swelling of the region, and numbness or paresthesia, while teeth loosening, toothache, and dysphagia are occasionally traced [5, 19]. In our case, CMEC presented as main symptoms pain and swelling. Evaluation of the panoramic radiographs and the CT imaging reveals that, generally, CMEC is depicted as a multilocular lesion with welldefined sclerotic bone margins. The substance of the lesion gives the impression of an amorphous sclerotic bone, while the borders of the loculations might be undistinguishable. CT reveals expanded cortical plate sometimes perforated by the CMEC [20]. Perforation of the cortex usually indicates high degree of histologic malignancy and worse prognosis [21]. Although this was present in our case, the patient is recurrence-free 6 years postoperatively. Radiographical features of CMEC are not pathognomonic, and for this reason, CMEC is frequently misdiagnosed as a cyst or a benign odontogenic tumor, like a glandular odontogenic cyst, an ameloblastoma or a keratocystic odontogenic tumor [20]. Diagnosis of CMEC is ensured using the following criteria: (a) presence of intact cortical plates, (b) radiographic evidence of bone destruction, (c) histopathologic confirmation, (d) positive mucin staining, (e) absence of primary lesion in salivary glands, and (f) exclusion of an odontogenic tumor [10, 13, 22]. CMEC has been classified in three different grades by Brookstone and Huvos. Grade 1 includes lesions without any expansion or perforation of the cortical plate, grade 2 includes lesions with distinguishable expansion but no perforation of the cortical plate, and grade 3 includes lesions with perforation of cortical plates or connected with regional metastasis [23]. Typically, CMEC presents a rapid onset with clinical symptoms of bone expansion, destruction of local structures, and pain which may be observed in the first year. However, it usually affects only surrounding tissues and is only locally aggressive [14]. Generally, CMEC is not characterized of invasiveness [13], and according to Brookstone and Huvos, only 9 % of the patients with CMEC represent traces of metastatic disease [23]. Reported metastases are mainly to the lymph nodes of the region. Nonetheless, metastases in ipsilateral clavicle, lung, and brain involvement have also been observed [5]. In the presented case, there were no affected lymph nodes found, although the lesion was extended on both sides of the midline and the preoperative radiological findings showed an erosion of the cortical plates. The prognosis is difficult to evaluate, and the best treatment is unestablished due to the rarity of CMEC which renders it difficult to come to a conclusion [24]. Treatment of choice is usually surgery, including curettage, enucleation,
Oral Maxillofac Surg
marsupialization, and wide local excision [9]. Patients treated with conservative surgical methods display recurrence in 40 %. Therefore, radical methods like segmental resection should be preferred [4], while neck dissection and adjunctive therapy may be applied depending on the severity of each case [25]. In our case, we decided for a wide excision with simultaneously performed bilateral selective neck dissection, due to the biopsy histological report which mentioned a malignancy. In conclusion, CMEC is a rare tumor of the jaws, which is only locally aggressive and has most frequently a good prognosis if treated with wide surgical excision. As the most common site of affection is the posterior region of the mandible, occurrence of the anterior region tends to be an exceptionally rare finding. Therefore, the case we present is of great interest not only because of the location of the CMEC but also because of its huge dimensions. Total treatment management including tumor resection, bilateral SND, soft, and hard tissue reconstruction, followed by implant supported overstructure, led to a satisfactory functional and esthetic outcome with a good prognosis. Conflict of interest The authors declare that they have no conflict of interest.
References 1. Grubka JM, Wesley RK, Monaco F (1983) Primary intraosseous mucoepidermoid carcinoma of the anterior part of the mandible. J Oral Maxillofac Surg 41:389–394 2. Goldfarb D, Mikaelian D, Keane W (1994) Mucoepidermoid carcinoma of the mandible. Am J Otolaryngol 15:54–57 3. Varma S, Shameena PM, Sudha S, Nair RG, Varghese IV (2012) Clear cell variant of intraosseous mucoepidermoid carcinoma: report of a rare entity. J Oral Maxillofac Pathol 16:141–144 4. Simon D, Somanathan T, Ramdas K, Pandey M (2003) Central mucoepidermoid carcinoma of mandible—a case report and review of the literature. World J Surg Oncol 1:1 5. Maremonti P, Califano L, Mangone GM, Zupi A, Guida G (2001) Intraosseous mucoepidermoid carcinoma. Report of a long-term evolution case. Oral Oncol 37:110–113 6. Martinez-Madrigal F, Pineda-Daboin K, Casiraghi O, Luna MA (2000) Salivary gland tumors of the mandible. Ann Diagn Pathol 4: 347–353 7. Baj A, Bertolini F, Ferrari S, Sesenna E (2002) Central mucoepidermoid carcinoma of the jaw in a teenager: a case report. J Oral Maxillofac Surg 60:207–211 8. Cutilli T, Corbacelli A (1999) Central mucoepidermoid carcinoma of the mandibular condyle. J Chemother 11:234–236 9. Raut DL, Khedkar SA (2009) Primary intraosseous mucoepidermoid carcinoma of the maxilla: a case report and review of the literature. Dentomaxillofac Radiol 38:163–168
10. Browand BC, Waldron CA (1975) Central mucoepidermoid tumors of the jaws. Report of nine cases and review of the literature. Oral Surg Oral Med Oral Pathol 40:631–643 11. Sidoni A, D’ Errico P, Simoncelli C, Bucciarelli E (1996) Central mucoepidermoid carcinoma of the mandible: report of a case treated 13 years after first radiographic demonstration. J Oral Maxillofac Surg 54:1242–1245 12. Kochaji N, Goossens A, Bottenberg P (2004) Central mucoepidermoid carcinoma: case report, literature review for missing and available information and guideline proposal for coming case reports. Oral Oncol Extra 40:95–105 13. Pincock JL, El-Mofty SK (1985) Recurrence of cystic central mucoepidermoid tumor of the mandible. Int J Oral Surg 14:81–84 14. Johnson B, Velez I (2008) Central mucoepidermoid carcinoma with an atypical radiographic appearance. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 106:e51–e53 15. Ntomouchtsis A, Xinou K, Patrikidou A, Paraskevopoulos K, Kechagias N, Tsekos A, Balis GC, Gerasimidou D, Thuau H, Mangoudi D, Vahtsevanos K (2013) Pilot study of intraoperative digital imaging with the use of a mammograph for assessment of bone surgical margins in the head and neck region. Clin Radiol 68: e136–e142 16. Tucci R, Matizonkas-Antonio LF, de Carvalhosa AA, Castro PH, Nunes FD, Pinto DD Jr (2009) Central mucoepidermoid carcinoma: report of a case with 11 years’ evolution and peculiar macroscopical and peculiar macroscopical and clinical characteristics. Med Oral Patol Oral Cir Bucal 14:E283–E286 17. Pires FR, Paes de Almeida O, Lopes MA, da Cruz E, Perez D, Kowalski LP (2003) Central mucoepidermoid carcinoma of the mandible: report of four cases with long-term follow-up. Int J Oral Maxillofac Surg 32:378–382 18. Namin AK, Moshref M, Shahoon H, Mashhadi A, Khojasteh A (2005) Intraosseous mucoepidermoid carcinoma of the maxilla in a teenager: a case report and review of literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 100:e93–e96 19. He Y, Wang J, Fu HH, Zhang ZY, Zhuang QW (2012) Intraosseous mucoepidermoid carcinoma of jaws: report of 24 cases. Oral Surg Oral Med Oral Pathol Oral Radiol 114:424–429 20. Chan KC, Pharoah M, Lee L, Weinreb I, Perez-Ordonez B (2013) Intraosseous mucoepidermoid carcinoma: a review of the diagnostic imaging features of four jaw cases. Dentomaxillofac Radiol 42: 20110162 21. Inagaki M, Yuasa K, Nakayama E, Kawazu T, Chikui T, Kanda S, Yoshikawa H, Nakamura S, Shinohara M (1998) Mucoepidermoid carcinoma in the mandible. Findings of panoramic radiography and computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 85:613–618 22. Tornes K, Bang G, Møller P (1987) Central mucoepidermoid tumor of the mandible. Report of 2 cases. J Craniomaxillofac Surg 15:38–41 23. Brookstone MS, Huvos AG (1992) Central salivary gland tumors of the maxilla and the mandible: a clinicopathologic study of 11 cases with an analysis of the literature. J Oral Maxillofac Surg 50:229–236 24. De Mello-Filho FV, Brigato RR, Mamede RC, Ricz HM, Saggioro FP, Xavier SP (2008) Central mucoepidermoid carcinoma: report of 2 cases. Br J Oral Maxillofac Surg 46:239–241 25. Chiu GA, Woodwards RT, Benatar B, Hall R (2012) Mandibular central mucoepidermoid carcinoma with distant metastasis. Int J Oral Maxillofac Surg 41:361–363
CASE REPORT
Central mucoepidermoid carcinoma of the anterior region of the mandible: report of an unusual case and review of the literature Nikos Kechagias & Aris Ntomouchtsis & Alexandra Mavrodi & Barbara Christoforidou & Antonis Tsekos & Kostas Vahtsevanos
Received: 5 November 2014 / Accepted: 5 January 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Introduction Central mucoepidermoid carcinoma is a rare lesion, whose exact pathogenesis is still not fully understood. Generally, it is more frequently encountered in the mandible than in the maxilla and in the posterior than in the anterior aspect of the jaws. Cases of central mucoepidermoid carcinomas are rarely mentioned in the literature, and therefore, additional information concerning this type of lesion is needed. Case report In the present paper, we report an extremely unusual case of a central mucoepidermoid carcinoma in the anterior region of the mandible of a 37-year-old female patient. The diagnosis and the surgical management of the tumor along with the reconstructive techniques utilized to restore the mandible and a 6-year follow-up are discussed. Discussion Central mucoepidermoid carcinoma is an unusual tumor of the jaws, especially in the anterior region. It is only locally aggressive and has most frequently a good prognosis if treated with wide surgical excision.
N. Kechagias Division of Oral & Maxillofacial Surgery, Clinic St. Loukas, Thessaloniki, Greece A. Ntomouchtsis Private Praxis, Luzern, Switzerland A. Mavrodi (*) : K. Vahtsevanos Department of Oral and Maxillofacial Surgery, Aristotle University of Thessaloniki, Thessaloniki, Greece e-mail: [email protected] B. Christoforidou Department of Histopathology, Theagenion Cancer Hospital of Thessaloniki, Thessaloniki, Greece A. Tsekos Oral & Maxillofacial Department, Army General Hospital of Thessaloniki, Thessaloniki, Greece
Keywords Central mucoepidermoid carcinoma . Anterior . Mandible . Diagnosis . Surgical management . Follow up
Introduction Mucoepidermoid carcinoma (MEC) was initially described as an entity in 1945 by Steward et al. [1]. Histologically, it is characterized by three main cell types, mucin-producing, epithelial, and intermediate cells [2, 3], and it constitutes 5–10 % of all salivary gland tumors affecting most commonly the parotid gland (89.6 %) and less frequently the submandibular (8.4 %) and sublingual salivary gland (0.4 %) [4]. Lepp was the first to report an intraosseous mucoepidermoid carcinoma located in the mandible of a 66-year-old woman [5]. Ectopic salivary gland tissue has also been detected in even more distant parts of the body, like the thyroid, the hypophysis, the mastoid bone, the middle ear, and the skin [6, 7]. Nonetheless, central mucoepidermoid carcinoma (CMEC) is far more frequent in the mandible and in the maxilla than in other bones, due to the close relationship of the mesenchymal to the ectodermic tissue in these particular bones, which may result in epithelial tissue entrapment during bone growth [8]. Despite the fact that MEC is the most frequent malignant salivary gland tumor, CMEC as a primary intraosseous bony lesion is much more rare, with an incidence of 2–4.3 % of all MECs reported [9]. Regarding its origin, several theories have been proposed; however, its exact pathogenesis is still uncertain and not fully understood. CMEC affects in a higher ratio females than males [6, 10–12]. Ιt has been observed in all age groups but is more common in the mandible during the 4th and 5th decades [4, 10]. Furthermore, CMEC is more frequently encountered in the mandible than in the maxilla [13, 14].
Oral Maxillofac Surg
In this paper, we report a case of a CMEC in the anterior region of the mandible of a 37-year-old female patient. Surgical management of tumor resection and bone defect reconstruction along with special intraoperative imaging techniques, plus a 6-year follow-up period are presented. Case report A 37-year-old female patient was referred to the Department of Maxillofacial Surgical Oncology Theagenio Cancer Hospital with a chief complaint of pain in the anterior teeth region of the mandible, which was present for 6 months prior to seeking medical attention. Clinical examination revealed a bony hard swelling involving the anterior region of the mandible from the right second premolar to the left first premolar. The overlying mucosa was intact with no signs of infection, while cervical lymphadenopathy was absent. There was no significant past medical history, except for mitral valve prolapse, and the patient reported no extraoral or intraoral trauma in the region and no former oral surgical interventions. Panoramic radiograph showed a multilocular, expansile osteolytic lesion extending from the distal aspect of the right second premolar to the mesial aspect of the left second premolar (Fig. 1). A computed tomography scan (CT) confirmed the presence of the osteolytic lesion and displayed expanded lingual and buccal cortices with some signs of cortical erosion (Fig. 2). No abnormalities were observed regarding cervical lymph nodes or soft tissues and organs of the head and neck region. With a provisional clinical diagnosis of an ameloblastoma, an incisional biopsy was performed under local anesthesia. Histopathological examination showed cystic spaces lined by slightly thickened cuboidal, epidermoid, columnar and mucous epithelial cells adjacent to lameral bone. The simultaneous presence of mucous and squamoid epithelium
Fig. 1 Panoramic radiograph showing a multilocular osteolytic lesion extending from the distal aspect of the right second premolar to the mesial aspect of the left second premolar
Fig. 2 Axial CT image depicting an extensive osteolytic lesion. Expanded lingual and buccal cortices with some signs of cortical erosion are traced
suggested a mucoepidermoid carcinoma. However, clear evidence of infiltration was not present in the otherwise restricted biopsy specimen (Fig. 3). Since biopsy results were inconclusive but suggested a diagnosis of a mucoepidermoid carcinoma, excision of the whole mass was planned out. Segmental mandibulectomy extending from the distal aspect of the right first molar to the distal aspect of the left second molar, involving all of the
Fig. 3 Photomicrograph of the biopsy specimen showing cystic spaces lined by slightly thickened cuboidal, epidermoid, columnar, and mucous epithelial cells (HEX200)
Oral Maxillofac Surg
thirteen mandibular teeth of the patient was performed. Additionally, bilateral selective neck dissection (levels I–III) was carried out. The gross specimen measured 7.5×5.5×4 cm and involved thirteen teeth. Macroscopically, an intraosseous polycystic lobular formation was observed with a largest diameter of 6 cm. The surgical margins of the specimen were additionally evaluated intraoperatively using digital mammograph imaging according to the method proposed by Ntomouchtsis et al. (Fig. 4) [15]. Digital images of the mandible indicated clinically complete excision. Due to the large dimensions and the location of the mandibular defect, a reconstruction of the mandible was necessary in order to achieve functional and cosmetic restoration. Specifically, reconstruction with a free rib graft and plate osteosynthesis was performed. In order to achieve soft tissue cover of the graft, a bilateral naso-labial flap was utilized. Histopathological examination revealed that the neoplasm was mainly consisted of numerous cystic spaces lined by columnar, mucous, intermediate, and epidermoid epithelial cells. In some places, there were more solid areas with mild atypia among mature appearing bony trabeculae. Based on these morphologic criteria, combined with the radiologic ones (osteolytic lesion with signs of cortical erosion), the diagnosis of a central mucoepidermoid carcinoma of low grade malignancy was confirmed (Fig. 5). Moreover, only traces of reactive lemphadenitis were found, and no lymph nodes infiltrated by tumor in the neck dissections specimens were discovered. Since the resection margins were negative for malignancy, the patient did not undergo any other therapy. Magnetic resonance imaging (MRI) showed no signs of recurrence 7 months after the surgery (Fig. 6). Fifteen months after the surgery, the patient remained disease-free and sought further medical attention in order to restore her chewing ability. Since there was a lack of sufficient bone support owing to the reduced height of the rib graft, a microvascular osteocutaneous fibula flap was utilized to restore the missing bone height. Secondary operations in terms of implant
Fig. 5 a Photomicrograph showing multiple cystic spaces lined by columnar, mucous, intermediate, and epidermoid epithelial cells along with mature appearing bony trabeculae (HEX100). b More solid areas with mild atypia (HEX200)
insertion and eventual dental rehabilitation were performed (Fig. 7). The patient is currently disease-free and satisfied with her functional and cosmetic status 6 years after the excision of the tumor.
Discussion
Fig. 4 Intraoperative evaluation of the surgical margins of the specimen using digital mammograph imaging
CMC is more common in the mandible than in the maxilla and in the posterior than in the anterior aspect of the jaws [6, 9]. Specifically, only 3 % of all discovered CMECs are encountered in the anterior mandible and maxilla [12]. Browand and Waldron reported three cases of an anteriorly located CMEC in the mandible, out of which only one crossed the midline extending from the left to the right canine region [10]. Grubka et al. described a case of a CMEC located in the right anterior mandible [1], whereas Tucci et al. reported a more extensive CMEC in the anterior mandibular region between the molars
Oral Maxillofac Surg
Fig. 6 MRI image indicating complete excision of the lesion and no signs of recurrence
[16]. Our case is a highly rare finding constituting an extremely unusual CMEC of the anterior part of the mandible crossing the midline and extending from the left second premolar to the right second premolar. As regards CMEC’s histogenesis, although multiple theories have been suggested, no hypothesis can sufficiently explain the pathogenesis of all these lesions. The most possible origins are as follows: (a) metaplasia of mucus-secreting cells from the lining epithelium of dentigerous cysts, (b) retromolar mucous gland tissue that has been entrapped and later underwent neoplastic transformation, and (c) embryologically entrapped submandibular and sublingual salivary gland tissue within the mandible during development. As proposed, other
Fig. 7 Panoramic radiograph 4 years after the surgery showing bone structures along with implants and dental rehabilitation
possible sources of origin of CMEC may also be as follows: metaplasia and invasion from the maxillary sinus epithelium, odontogenic remnants of the dental lamina or iatrogenic entrapment of minor salivary glands (e.g., chronic osteomyelitis and sinusitis) [10, 17, 18]. Clinically, patient’s main symptoms when affected by CMEC include pain, swelling of the region, and numbness or paresthesia, while teeth loosening, toothache, and dysphagia are occasionally traced [5, 19]. In our case, CMEC presented as main symptoms pain and swelling. Evaluation of the panoramic radiographs and the CT imaging reveals that, generally, CMEC is depicted as a multilocular lesion with welldefined sclerotic bone margins. The substance of the lesion gives the impression of an amorphous sclerotic bone, while the borders of the loculations might be undistinguishable. CT reveals expanded cortical plate sometimes perforated by the CMEC [20]. Perforation of the cortex usually indicates high degree of histologic malignancy and worse prognosis [21]. Although this was present in our case, the patient is recurrence-free 6 years postoperatively. Radiographical features of CMEC are not pathognomonic, and for this reason, CMEC is frequently misdiagnosed as a cyst or a benign odontogenic tumor, like a glandular odontogenic cyst, an ameloblastoma or a keratocystic odontogenic tumor [20]. Diagnosis of CMEC is ensured using the following criteria: (a) presence of intact cortical plates, (b) radiographic evidence of bone destruction, (c) histopathologic confirmation, (d) positive mucin staining, (e) absence of primary lesion in salivary glands, and (f) exclusion of an odontogenic tumor [10, 13, 22]. CMEC has been classified in three different grades by Brookstone and Huvos. Grade 1 includes lesions without any expansion or perforation of the cortical plate, grade 2 includes lesions with distinguishable expansion but no perforation of the cortical plate, and grade 3 includes lesions with perforation of cortical plates or connected with regional metastasis [23]. Typically, CMEC presents a rapid onset with clinical symptoms of bone expansion, destruction of local structures, and pain which may be observed in the first year. However, it usually affects only surrounding tissues and is only locally aggressive [14]. Generally, CMEC is not characterized of invasiveness [13], and according to Brookstone and Huvos, only 9 % of the patients with CMEC represent traces of metastatic disease [23]. Reported metastases are mainly to the lymph nodes of the region. Nonetheless, metastases in ipsilateral clavicle, lung, and brain involvement have also been observed [5]. In the presented case, there were no affected lymph nodes found, although the lesion was extended on both sides of the midline and the preoperative radiological findings showed an erosion of the cortical plates. The prognosis is difficult to evaluate, and the best treatment is unestablished due to the rarity of CMEC which renders it difficult to come to a conclusion [24]. Treatment of choice is usually surgery, including curettage, enucleation,
Oral Maxillofac Surg
marsupialization, and wide local excision [9]. Patients treated with conservative surgical methods display recurrence in 40 %. Therefore, radical methods like segmental resection should be preferred [4], while neck dissection and adjunctive therapy may be applied depending on the severity of each case [25]. In our case, we decided for a wide excision with simultaneously performed bilateral selective neck dissection, due to the biopsy histological report which mentioned a malignancy. In conclusion, CMEC is a rare tumor of the jaws, which is only locally aggressive and has most frequently a good prognosis if treated with wide surgical excision. As the most common site of affection is the posterior region of the mandible, occurrence of the anterior region tends to be an exceptionally rare finding. Therefore, the case we present is of great interest not only because of the location of the CMEC but also because of its huge dimensions. Total treatment management including tumor resection, bilateral SND, soft, and hard tissue reconstruction, followed by implant supported overstructure, led to a satisfactory functional and esthetic outcome with a good prognosis. Conflict of interest The authors declare that they have no conflict of interest.
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