Introduction

Malignant odontogenic tumors are rare groups of malignant cancers, which arise from remnants of odontogenic epithelium [ 1 ]. One of these tumors is odontogenic carcinosarcoma (OCS), an extremely rare malignant odontogenic tumor in which both the epithelial and the ectomesenchymal components demonstrate malignant features cytologically [ 2 - 6 ].

There are few published case reports of OCS in the literature and they were not specified in WHO classification until 1992 [ 7 ]. Therefore, its clinical appearance is unclear. However the review of literature demonstrates that these rarely malignant cases have exhibited aggressive clinical behavior [ 8 - 9 ].

OCS is related with some tumors which comprise of lesions that range from benign epithelial tumors such as ameloblastoma and ameloblastic fibroma to malignant tumors with metastatic potential like ameloblastic fibrosarcoma [ 9 , 10 ], but due to the scarcity of reported cases, this transformation remains unexplored. There are only twelve OCS cases in the English literature [ 7 - 8 ].

In this report, we describe a case which will be the thirteenth case of OCS arising from an ameloblastic fibroma in the mandible of 33 years-old male patient.

Case Presentation

A 33-year-old male was presented with a painful mass in the anterior of mandible. Patient suffered from a progressive swelling and alternating paresthesia for approximately 4 months with no complaint of dysphagia, fever, trismus, and weight loss. Past medical history revealed an ameloblastic fibroma in the same region 10 years ago, performed outside our institute, when he was treated by conservative surgery with enucleation.

Physical examination exhibited a poorly defined swelling over the anterior body of mandible with smooth surface roughly 3×4cm in size; no adenopathy was noted. Computed tomography examination displayed a unilocular area of radiolucency with indistinct margins, cortical expansion and buccal cortex perforation (Figure 1).

Figure 1.a: Computed tomography of odontogenic carcinosarcoma, axial view showing the unilocular lesion extending from the lower right lateral incisor to the up to lower left second premolar, b: Three-dimensional image view with buccal perforation and pathological fracture, c and d: Immediate reconstruction

An incisional biopsy was performed. Macroscopically, a whitish soft tissue with elastic texture was observed. According to the clinical imaging and microscopic features, the diagnosis at the time of incisional biopsy was odontogenic carcinosarcoma with malignant characteristic in both odontogenic and mesenchymal parts of tumor. Partial mandibular resection consisting wide surgical excision from the lower right lateral incisor up to the lower first molar with immediate reconstruction was accomplished (Figure 2).

Figure 2.Gross examination; a: Partial mandibular resection consisting wide surgical excision, b: Cross-section of the resected specimen showing the necrotic fistula on the alveolar ridge, from the lower right lateral incisor up to the lower left first molar, c and d: Immediate reconstruction

On histopathological examination, all the margins were free of tumor infiltration. Microscopic examination demonstrated a biphasic malignant neoplasm with both epithelial and mesenchymal malignant feature. Epithelial components were in the form of strands and islands with a peripheral palisaded layer of cuboidal or columnar cells and central stellate reticulum like cells. Epithelial component showed malignant features like hyperchromatism of nuclei, pleomorphism, increased nuclear-to-cytoplasmic ratio and abnormal mitotic figures. Mesenchymal element also exhibited malignant features including enlargement of nuclei, hyperchromatism, hypercellularity, and occasional mitoses (Figure 3). The patient is currently being followed up for 16 m-onths with good healing and no sign of recurrence and metastasis.

Figure 3.Histopathological examination of the recurred lesion (hematoxylin and eosin stain), a: Microscopic image showing odontogenic epithelial follicles formed of ameloblast-like cells on the periphery and stellate-reticulum like cells on the center, which were surrounded by primitive ectomesenchyme resembling dental papilla (100×), b: Microscopic image showing hypercellular epithelial follicles with plump hyperchromatic (blue arrow) and pleomorphic cells, bizarre shaped nuclei and increased nuclear/ cytoplasmic ratio (green arrow) (400×), c: Microscopic image showing hypercellular ectomesenchyme (100×), d: Microscopic image showing atypia in ectomesenchymal component with increased mitosis (black and orange arrows, 200×)

Discussion

Malignant odontogenic tumors have exceedingly rare incidence but nonetheless they occur [ 2 ]. Odontogenic malignancies have different origins. Some arise from odontogenic epithelial remnants, residues from embryologic odontogenesis process. Others may develop from preexisting lesions. The mechanism of these transformations is not thoroughly elucidated [ 10 ].

As has been demonstrated, the proceeding of odontogenesis involves inductive interaction between the enamel organ and the ectomesenchyme of dental papilla.

It seems that similar induction can cause malignant odontogenic neoplasms like the process occurring in odontogenesis [ 11 ].

OCS is a rare malignant mixed odontogenic tumor which both the epithelial and the mesenchymal component present malignant properties. Until now, twelve cases of OCS are reported in the English literature. Four out of twelve cases published in the English literature were considered as de novo [ 10 - 11 ], and other cases were occurred because of previous surgery or were arisen from a preexisting lesion [ 12 ] (Table 1).

Chikosi et al. [ 6 ] demonstrated the OCS which has been upraised from ameloblastoma and the OCS that has been reported by DeLair et al. [ 5 ] was originated from an ameloblastic fibroma. The cases, which have been reported by Kunkel et al. [ 4 ], were developed from ameloblastic fibrosarcoma.

Although the mechanism of malignant transformation from the benign previous odontogenic lesion is relative unknown, but it is reported that surgical trauma, multiple surgical resection, and radiotherapy seem to have important role in deriving reported cases [ 13 ].

In the English literature, there was a male predilection and two cases presented in maxilla [ 14 ]. It is notable that odontogenic carcinosarcoma occurs more commonly in the posterior of mandible, but our case has been existed from anterior part of mandible [ 15 ].

Most of the cases are treated by surgical resection. Some studies revealed that less aggressive resection cause an increase in the possibility of recurrence [ 14 ]. In our case, partial mandibular resection with wide surgical excision was performed and the patient is currently being followed up.

In the English literature, seven out of the twelve cases showed recurrence of the lesion and only 4 cases showed metastasis.

Conclusion

This is a case report of odontogenic carcinosarcoma with mixed features of both carcinomatous and sarcomatous components on histopathological evaluation. In spite of limited information about the clinical behavior of OCS, these tumors are very aggressive with high rates of recurrence and metastasis. However, partial resection of mandible seems to be the best treatment, considering the poor outcome of the lesion.

Acknowledgement

The authors wish to thank the Research Consultation Center (RCC) of Shiraz University of Medical Sciences for editing this manuscript.

Conflict of Interest

The authors declare that they have no conflict of interest.

References

1. El Naggar AK, Chan JKC, Grandis JR, Takata T, Slootweg PJ. WHO Classification of Head and Neck Tumours. IARC Press: Lyon; 2017.
2. Tanaka T, Ohkubo T, Fujitsuka H, Tatematsu N, Oka N, Kojima T, et al. Malignant mixed tumor (malignant ameloblastoma and fibrosarcoma) of the maxilla. Arch Pathol Lab Med. 1991; 115: 84-87.
3. Slama A, Yacoubi T, Khochtali H, Bakir A. Mandibular odontogenic carcinosarcoma: a case report. Rev Stomatol Chir Maxillofac. 2002; 103: 124-127.
4. Kunkel M, Ghalibafian M, Radner H, Reichert TE, Fischer B, Wagner W. Ameloblastic fibrosarcoma or odontogenic carcinosarcoma: a matter ofclassification?. Oral Oncol. 2004; 40:444-449.
5. DeLair D, Bejarano PA, Peleg M, El Mofty SK. Amelob-lasticcarcinosarcoma of the mandible arising in ameloblastic fibroma: a case report and review of the literature. Oral Surg Oral Med OralPathol Oral Radiol Endod. 2007; 103: 516-520.
6. Chikosi R, Segall N, Augusto P, Freedman P. Odontogenic carcinosarcoma: case report and literature review. J Oral Maxillofac Surg. 2011; 69: 1501-1507.
7. Kramer R, Pindborg J, Shear M. The WHO histological typing of odontogenic tumors. Cancer. 1992; 70: 2988-2994.
8. Slootweg PJ. Malignant odontogenic tumors: an overview. Mund Kiefer Gesichtschir. 2002; 6: 295-302.
9. Schuch LF, de Arruda JAA, Silva LVO, Abreu LG, Silva TA, Mesquita RA, Schuch. Odontogenic carcinosarcoma: A systematic review. Oral Oncol. 2018; 85: 52-59.
10. Kim IK, Pae SP, Cho HY, Cho HW, Seo JH, Lee DH, et al. Odontogenic carcinosarcoma of the mandible: a case report and review. J Korean Assoc Oral Maxillofac Surg. 2015; 41: 139-144.
11. Da Silva KD, Flores IL, Etges A.  Unusual osteolytic lesion of the jaw. Oral Surg Oral Med Oral Pathol Oral Radiol.  2017; 124: 443-448.
12. Soares CD, Delgado Azañero W, Morais TMDL, de Almeida OP, Ghersi Miranda H. Odontogenic Carcinosarcoma: Clinicopathologic Features of 2 Cases. Int J Surg Pathol. 2020; 28: 421-426.
13. Mahmoud Salem HW, Mahmoud Badawy SA, Amer HW. Odontogenic carcinosarcoma arising from premature odontoma with immunohistochemical profile. F1000Research. 2020; 9: 603.
14. Dos Santos JN, Servato JPS, Cardoso SV de Faria PR, Pires BC, Loyola AM. Odontogenic carcinosarcoma: morphologic and immunohistochemical description of a case.  Oral Surg Oral Med Oral Pathol Oral Radiol.  2018;  126: 264-270.
15. Schuch LF, de Arruda JAA, Silva LVO, Abreu LG, Silva TA, Mesquita RA. Odontogenic carcinosarcoma: a systematic review. Oral Oncol. 2018; 85: 52-59.