Ameloblastic fibrosarcoma arising in the mandible

Fibrosarcoma ameloblástico en la mandíbula

This work is licensed under Creative Commons Attribution 4.0 International.

Ameloblastic Fibrosarcoma (AFS) is a rare odontogenic neoplasm and is considered the malignant counterpart of Ameloblastic Fibroma (AF). Histologically, AFS' mesenchymal portion shows malignant features of sarcoma, which is mixed to a benign ameloblastomatous epithelial component. This tumor either presents de novo or arises from a pre-existing AF.^{1,2,3,4,5,6,7}

There is a predilection for males between 26 and 27 years, and posterior mandible area as the most frequent site of occurrence, being locally aggressive.^{1,6,7,8,9,10,11} Until 2012, only 72 cases were published in English-literature, which indicate strong tendency to recur but rare metastases of AFS.¹

FIG. 1

A) Image from intraoral mass in detail. B) Detail of the initial panoramic radiography. Observe the multilocular radiolucent lesion with ill-defined borders and tooth involvement. C) and D) CT images (bone window), axial view and coronal view, respectively. Observe hypodense lesion leading to expansion, tapering and irregular destruction of cortical, and tooth involvement. E) and F) CT images (soft tissue window), axial view and coronal view respectively. Observe the hypodense areas within an infiltrative lesion. Besides the low contrast penetration, in some areas, it leaks out of the lesion.

The objective of this report is to present a rare case of Ameloblastic Fibrosarcoma.

23-year-old female patient was refered to Heliópolis Hospital (São Paulo-Brazil) penetration, and, in some areas, it overflows the lesion (Fig. 1E, 1F).

FIG. 2

A) Microscopic evaluation, representing the epithelial area with nests and thin plexiform anastomosing cords and strands of odontogenic epithelium. B) Microscopic evaluation, representing the mesenchymal area with spindle and stellate cells that exhibited moderate nuclear pleomorphism and vesicular to densely hyperchromatic chromatin. C) AE1-AE3 cytokeratin labelling the epithelial component of the tumor. D) Vimentin labelling the mesenchymal component of the tumor. E) Intense p53 labeling in all tumoral cells.

Incisional biopsy was performed under local anesthesia. The histopathological evaluation revealed a mixed lesion with epithelial and mesenchymal cellular proliferation. The epithelial portion was composed by nests and thin plexiform anastomosing cords and strands of odontogenic epithelium exhibiting peripheral palisading and reverses nuclear polarity, as well as small central areas of stellate reticulum-like areas (Fig. 2A). The mesenchymal proliferation consisted on spindle and stellate cells that exhibited moderate nuclear pleomorphism and vesicular to densely hyperchromatic chromatin. Typical sarcomatous perivascular cellular concentration was also noted (Fig. 2B).

By immunohistoquemical analisys, vimentin and cytokeratin AE1-AE3 were positive in mesenchymal and epithelial components, respectively. Tumoral cells showed intense labeling by p53 (Fig. 2C, 2D, 2E) The final diagnosis was ameloblastic fibrosarcoma.

FIG. 3

Imges form patient’s recovering. A) and B) images from a month of follow up; C) and D), from eight months of follow up. Note the facial symmetry and midline correspondence between jaws.

The treatment consisted in surgical excision followed by area reconstruction. The lesion was accessed through submandibular approach under general anesthesia, and hemimandibulectomy and selective neck dissection (level I) were preformed. A titanium plate was placed for mandibular reconstruction. One month after surgery, the patient returned for routine evaluation. Eight months after surgery, patient presented a good recover without complications or recurrence signals (Fig. 3).

Head and neck sarcoma are rare tumors, corresponding to 4 %-10 % of all sarcoma. In maxillofacial area, these tumors are even rarer, representing less than 5 % of all odontogenic tumors, and AFS is the less frequent from all types of sarcoma^9,12,13,14. Only a third of currently published cases of AFS have originated from a recurrent AF, and this may be the cause of doubtful etiology.^8,10,11

Clinically, the tumor presents painful swelling and fast growth as.^8,9,10,11 The case hereby presented seems to be even rarer, since the patient is a woman. However, except for paresthesia, all clinical symptoms were observed.

A substantial number of conditions affecting the jaws may present tumor radiographic appearance. The differential diagnosis includes other odontogenic sarcomas, specifically those entities that present similar histological features, such as ameloblastic fibrodentinosarcoma and fibro-odontosarcoma.¹³ Because of the rapid growth, and intraoral and images aspects the lesion was thought to be a malignant odontogenic tumor. These entities are rare as primary head and neck the estimate rate comparing to hole body tumors.^15,16 This rarity makes the specific diagnosis really challenging.¹⁵

Radiographically, AFS appear as a radiolucent lesion with ill-defined borders.^2,3,5,13,14 Cortical may be eroded.^2,3,9 Images from CT exam usually present an invasive mass with cortical expansion and perforation.^2,3,11 CT is the method of choice for AFS evaluation, since it allows the observation of lesion's real expansion and adjacent structures involvement without image superimposition or distortions.¹¹ The panoramic radiography from the patient revealed the same features described in the literature. Besides that, CT images clearly showed cortical expansion and destruction, tooth involvement and loss of architecture of mandibular canal. Moreover, the low penetration of contrast during CT exam emphasizes the solid aspect of the lesion.

The microscopic features can be divided into two parts: the benign epithelial part, similar to ameloblastic lesion, and malignant mesenchymal part, with sarcomatous aspects.^{5,6,8,9,10,11,14}The epithelium presents columnar cells, with hyperchromatic nucleus. At mesenchymal tissue the cells are fusiform, with marked pleomorphism, hyperchromatism and abnormal mitotic figures.^{5,8,9,10,11,13} The importance and relevance of imunohistochemical analysis was also addressed, especially in cases of recurrence, with mitotic activity increased at mesenchyme and decreased epithelial evidences¹⁷. Despite the fact that there was no previous lesion, we have decided to investigate the lesion by imunohistochemical approach. The evaluation included vimentin and citokeratins AE1-AE3, and the results revealed the mixed outline of the lesion. The p53 evaluation also proved the alterations are well noticed at sarcomatous lesion.

The treatment of choice is surgical excision with clear margins, because AFS is a very invasive and recurrent lesion.^{1,3,4,6,7,8,9,10,11,13} Some authors also include a combination of chemotherapy, radiotherapy.^4,7,14 In the current case, the surgical excision was performed, without any recommendations of chemotherapy or radiotherapy as coadjutant treatment. After eight months from surgery, the patient didn't show any evidence of recurrence.

In conclusion, a rare case of an AFS is presented. The radiographic appearance, even imperative for treatment planning, poorly contributed to final diagnosis, which was reached by histopathological and immunohistochemical evaluations. The treatment is still controversial, without a definition regarding chemotherapy and radiotherapy as coadjutant treatment.

Los autores no declaran conflictos de intereses.