CLlNlCOPATHOLOGlC CONFERENCES J Oral Maxillofac Surg 401656-656. 1962

Case 41, Part II= An Unusual Ameloblastoma

L llm

of the Mandible

JAMES R. SANNER, DMD,* JOHN JARRETT, DDS,t

The patient was readmitted to the hospital. A complete history and physical examination, electrocardiogram, and laboratory studies were performed; the results were non- contributory. The patient was brought to the oral surgery clinic, where an intraoral evaluation revealed that the mandibular lesion was of a size similar to that seen two months earlier. Palpation of the mass demonstrated re- generation of buccal, lingual, and superior cortical plates. Osteogenesis of the cortices was confirmed by an occlusal radiograph.

Following administration of intravenous Valium, local anesthesia was administered to provide bilateral lingual and inferior alveolar nerve anaglesia. An incision was made at the crest of the mandibular ridge extending from the region of the right second molar to the left canine area, where a releasing incision was made. A flap was reflected subperiosteally to gain wide access on both buc- cal and lingual aspects. Once the flap had been reflected, inspection revealed that both lingual and buccal cortices were intact and that there was extreme thinning at the crest of the alveolar ridge. These conditions differed dra- matically from those seen at the first surgical exploration, when no buccal, lingual, or superior cortical bone was evident. Needle aspiration was performed through the thinned superior cortex, producing 10 ml of serosan- guineous fluid. Unroofing of the lesion was performed from the right first molar region to the midline of the mandible via a chisel technique. A reddish-purple cystlike membrane, several millimeters thick, was encountered (Fig. 1). A 3 x 3 cm lesion was delicately curetted from its bony crypt without difficulty. Following removal of the mass, there were clearly defined margins of bone in all directions and a very small perforation of the lingual plate (Fig. 2). The bony confines were carefully electrocau- terized, especially in the area of the lingual perfora- tion. The cavity was packed with quarter-inch iodoform gauze dressing, the end of which was brought through the flap via a stab incision buccally. The wound was closed with interrupted 3-O silk sutures. The patient had an une- ventful recovery. The packing was removed after two days, and the sutures were removed after seven days.

Histologic examination of the surgical specimens re- vealed considerable osteoid and new bone formation, and strips of densely collagenous, compressed connective tis- sue. Although much of this capsule-like tissue showed no epithelial lining, many areas had a lining composed of low cuboidal to stratified squamous epithelium (Fig. 3). This

* Chief, Oral Surgery Section, Veterans Administration Hos- pital, Columbia, South Carolina. ? Professor and Chairman, De- partment of Oral Pathology, Medical University of South Carolina School of Dental Medicine. $ Staff Periodontist, Veter- ans Administration Hospital, Columbia, South Carolina.

Address Correspondence and reprint requests to Dr. Sanner: Oral Surgery Section, Veterans Administration Hospital, Co- lumbia, SC 29201.

AND G. ALLEN BROOKS, DDSS

FIGURE 1. Above. Oral photograph showing the cystlike membrane intraoperatively.

FIGURE 2. B&W, Oral photograph showing clearly defined margins of bone with a small lingual perforation.

027%2391/82/1000/0656 $00.60 @ American Association of Oral and Maxillofacial Surgeons

656

SANNER ET AL 657

FIGURE 3. Aho,v. Photomicrograph of ameloblastoma showing large cystic area lined by low cuboidal to stratified squamous

rpithelium I * 100).

FIGURE 4. Below. Photomicrograph of cystlike epithelium showing ameloblastic budding (X 200).

658 AMELOBLASTOMA OF MANDIBLE

FIGURE 5. Histopathologic appearance of ameloblastoma showing microcyst formation occurring in several proliferating isiands of neoplastic epithelium (X 26). ^ _

partial epithelial lining featured numerous examples of ameloblastic-like budding, and within the stroma were many areas of clearly defined ameloblastoma (Fig. 4). Similar areas were observed forming microcysts as well as larger cystic structures (Fig. 5). An amorphous, acel- lular, hyalinized inductive effect was noted in most areas of ameloblastic proliferation as well as areas adjacent to the cystic lining epithelium.

The histologic features described are consistent with a cystic ameloblastoma. However, the lesion is unusual in having a relatively small size within so large a defect and in having an incomplete “cystic”epithelia1 lining despite its great cystic propensity.

Discussion: Dr. Sanner

The ameloblastoma is an odontogenic tumor that origi- nates from epithelial tissue. The tumor is usually benign and most frequently occurs in the mandible. It has a ten- dency for cortical expansion and local destruction, and usually appears radiographically as a multiloculated le- sion.rm4 Although the ameloblastoma is usually a solid lesion, it may, as in this case, be cystic.

During the first surgical exploration, no cystic lining was clinically apparent and the original histologic report was inconclusive. After only two months following the initial decompression and surgical exploration, rapid os- teogenesis and formation of a cystlike lesion had oc- curred. The original intent of the second exploration was merely to obtain sufficient tissue for a definitive diagno- sis. However, after the lesion had been unroofed, a

cystlike lesion was encountered. It was then decided to attempt a conservative enucleation procedure because of the ease of curettage, the patient’s age, and an uncon- firmed diagnosis. It was also believed that a conservative procedure combined with thorough electrocoagulation would allow for a reduction in the extent of surgical re- section and subsequent reconstructive surgery, if the mi- croscopic examination were to confirm the suspected di- agnosis of ameloblastoma.5

It is acknowledged that curettage and electrocautery is a less desirable procedure than more aggressive tech- niques when there is a confirmed diagnosis of ameloblas- toma. Because of the ease of curettage, the age of the patient, and an unconfirmed diagnosis, it is my belief that the proper procedure was employed.

Six months postoperatively, radiographs of the lesion show osseous regeneration at the operative site. The pa- tient will be followed up for possible recurrence.

References

1. Shafer WG, Hine MK, Levy BM: A textbook of Oral Pa- thology, 3rd ed. Philadelphia, WB Saunders Co, 1974, pp 251-258

2. Gorlin RJ, Goldman HM: Thoma’s Oral Pathology, 5th ed. St Louis, CV Mosby Co, 1970, pp 483-489.

3. Small IA, Waldon CA: Ameloblastoma of the iaws. Oral Surg 8281, 19.55

4. Waldron CA: Ameloblastoma in perspective. J Oral Surg _ _ 24:331, 1966

5. Pandya HJ, Stuteville OH: Treatment of ameloblastoma. Plast Reconstr Surg 50:242, 1972