Adenoid cystic carcinoma

Abstract

We report the case of a 74-year-old woman who developed a follicular ameloblastoma of the right mandible and 22 months later developed a cribriform adenoid cystic carcinoma of the soft palate on the right maxilla. The ameloblastoma was treated by hemimandibulectomy, and the adenoid cystic carcinoma was managed by resection of the soft palate and the surrounding tissue and bone followed by a 6-week course of radiotherapy. Our review of the literature indicates that only one similar case has been previously reported where an odontogenic tumor and a salivary, gland tumor involved two different anatomic locations in the same patient at nearly the same time.

Introduction

Ameloblastoma is the most common odontogenic tumor of epithelial origin, and its manifestations are part of a large spectrum of atypical clinical and pathologic findings. As a result, ameloblastoma continues to be a subject of intense interest and controversy, even after more than 100 years of recorded observation. (1) Ameloblastoma of the jaw is a relatively rare phenomenon, accounting for 1% of all tumors and cysts in the head and neck region and 11% of all odontogenic tumors.(2-4) Ameloblastoma can occur anywhere in the mandible or maxilla, although the mandibular molar area and the area around the ascending ramus appear to be the most common sites, (5,6) Ameloblastoma is usually a benign, locally infiltrative tumor, although it can undergo malignant transformation and metastasize. There appears to be general agreement that ameloblastomas are radioresistant, although some investigators regard them as radiosensitive. (4,5)

Ameloblastomas are divided into two biologic-microscopic subtypes: polycystic and unicystic. Both subtypes usually occur in the body of the mandible and in its ascending ramus. Unicystic ameloblastoma is generally associated with a lower rate of postoperative recurrence than is the polycystic form. Several bistologic patterns of ameloblastoma have been described. The most common microscopic subtype is the follicular pattern. (1,3,5) Two of the other subtypes are plexiform and acanthomatous. Some authors have suggested that the tumor subtype may be indicative of its future biologic behavior. (5,6)

Adenoid cystic carcinoma is a rare malignant tumor that affects the major and minor salivary glands, the lacrimal glands, the ceruminous glands, and occasionally the excretory glands of the female genital tract. (7) It accounts for approximately 10 to 15% of all head and neck tumors. (8) Approximately 50 to 70% of reported cases occur in the minor salivary glands. (3) The most common location is the palate, generally in the area of the greater palatine foramen. Adenoid cystic carcinoma is a radiosensitive tumor that is well known for its prolonged clinical course and its tendency for delayed distant metastasis. (3,7) Several histologic growth patterns have been described, including the cribriform or cylindromatous pattern, the tubular-trabecular pattern, and the solid basaloid pattern; in some cases, a combination of patterns is seen. (3)

In this article, we describe an unusual case of ameloblastoma of the mandible and adenoid cystic carcinoma of the soft palate covering the maxilla that occurred in the same patient at almost the same time. To our knowledge, only one similar case has heretofore been published. (9) We also provide a brief discussion of these two tumors based on the relevant literature.

Case report

A 74-year-old woman complained of a slowly growing, painless mass in the right mandible of 5 months' duration. On clinical examination, the mass was firm. The oral examination revealed firm swelling in the area of a missing molar and the dextrolateral pharynx. A panoramic x-ray examination revealed multilocular radiolucency in the ramus ascendens and the angulus mandibula on the right (figure 1).

[FIGURE 1 OMITTED]

With the patient under local anesthesia, an incisional biopsy was performed. The tissue was submitted for microscopic examination, and an ameloblastoma of the follicular type was diagnosed. The tumor was removed via block resection of the right mandible with exarticulation. An AO plate was inserted. On macroscopic examination, the resected specimen appeared as a soft-tissue mass attached to a segment of the mandible. A portion of the mandible had been destroyed and partly replaced by an ulcerating and partially encapsulated mass. The condyle of the temporomandibular joint was completely destroyed. The tumor margins were well defined. The specimen submitted to microscopic examination was found to include some tiny lymph nodes (figure 2). Operative biopsy confirmed that the tumor was an ameloblastoma of the follicular type (figure 3).

[FIGURES 2-3 OMITTED]

Some 22 months after the hemimandibulectomy, the patient noticed a painless mass in her soft palate. Preoperative histopathology indicated that it was an adenoid cystic carcinoma with a cribriform pattern. No evidence of bone involvement was seen on panoramic x-ray and computed tomography (CT), nor was there any clinical or radiologic evidence of cervical lymphatic metastasis. The tumor was removed by resection with wide margins of surrounding normal tissue and underlying bone. Histopathologic examination identified the tumor as an adenoid cystic carcinoma that featured both cribriform and tubular-trabecular patterns (figure 4). Findings on chest x-ray were normal. The patient was then treated with radiotherapy. Over a 6-week period, a total of 75 Gy was applied to the right maxillofacial region.

[FIGURE 4 OMITTED]

At 6 years of follow-up, the patient had experienced no clinical recurrence of the ameloblastoma or the adenoid cystic carcinoma. Because she was satisfied with the functional and aesthetic results of her surgeries, she declined to undergo bone reconstruction.

Discussion

Because ameloblastoma and adenoid cystic carcinoma are not related in terms of histogenesis, they are not very likely to occur in the same patient at nearly the same time. Whereas ameloblastoma arises from odontogenic epithelium, adenoid cystic carcinoma is believed to originate in the intercalated duct reserve cell or terminal tubule complex.(3)

According to specialty literature, only a few cases of ameloblastoma appear to be associated with other tumors. But even when ameloblastomas do occur with other tumors, the other tumors are usually either odontogenic or osseous lesions that share a common origin or location. Ameloblastoma has been reported to occur with calcifying odontogenic cyst, (10) traumatic neuroma, (11) aneurysmal bone cyst, (12) osteogenic sarcoma, (13) basal cell nevus syndrome, (14) glandular odontogenic cyst, (15) osteoblastoma, (16) and squamous cell carcinoma. (17)

Until now, only one case of both an ameloblastoma and a salivary gland tumor in the same patient at nearly the same time has been reported. (9) We can suggest two explanations for the lack of reports similar to ours in the literature:

* First, the overall incidence of both tumors is relatively low. According to statistical reports of jaw tumors, ameloblastoma is relatively rare, as the incidence is only 1%. (2-4) Adenoid cystic carcinoma (cylindroma) of the salivary glands is not uncommon, especially in the minor salivary glands. (3,8)

* Second, odontogenic tumors and salivary gland tumors affect different age groups, although there is some overlap. Ameloblastoma occurs primarily in patients between 30 and 50 years of age. (3-5) (At 74 years of age, our patient was much older than the average ameloblastoma patient.) Most patients with adenoid cystic carcinoma are aged between 40 and 70 years. (3,7,8) In our patient, the development of the two tumors followed a parallel course (the interval between the appearance of the two was only 22 months), but it is reasonable to believe that they occurred independently.

Adenoid cystic carcinoma is generally characterized by a slow growth rate, and it is often present for several years before a patient seeks treatment. Bone invasion occurs frequently, but radiographic changes are not evident initially. (3) When ameloblastoma and a concomitant tumor of the head and neck develop, it is difficult to identify the nature of the latter tumor on clinical grounds, because the biologic behavior of ameloblastomas varies considerably. The final diagnosis must be based on histologic investigation. In our patient, it is difficult to prove that the ameloblastoma and the adenoid cystic carcinoma had involved both the mandible and the maxillary region at the same time, because when the ameloblastoma appeared, there were no signs of any neoplastic changes in the palate--that is, there was neither clinical nor radiologic evidence of the adenoid cystic carcinoma.

When two histologically unrelated tumors appear at different anatomic locations almost simultaneously, the differential diagnosis is of invaluable help in providing the patient with the best possible treatment that is targeted to minimizing tumor recurrence while maximizing functional and aesthetic results.

References

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(14.)Schultz SM, Twickler DM, Wheeler DE, Hogan TD. Ameloblastoma associated with basal cell nevus (Gorlin) syndrome: CT findings. J Comput Assist Tomogr 1987;11:901-4.

(15.) Hisatomi M, Asaumi J, Konouchi H, et al. A case of glandular odontogenic cyst associated with ameloblastoma: Correlation of diagnostic imaging with histopathological features. Dentomaxil lofac Radiol 2000;29:249-53.

(16.) Gordon SC, Macintosh RB, Wesley RK. A review of osteoblastoma and case report of metachronous osteoblastoma and unicystic ameloblastoma. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001 ;91:570-5.

(17.) Nishimura T, Nagakura R, Ikeda A, Kitas S. Simultaneous occurrence of a squamous cell carcinoma and an ameloblastoma in the maxilla. J Oral Maxillofac Surg 2000;58:1297-1300.

From the Department of Maxillotacial Surgery (Dr. Tamme and Dr. Leibur) and the Department of Pathology (Dr. Kulla), University of Tartu, Tartu, Estonia.

Reprint requests: Dr. Tiia Tamme, Department of Maxillofacial Surgery, University of Tartu, 8 L. Puusepa St., Tartu 51014, Estonia. Phone: 372-7-318-237; fax 372-7-318-224: e-mail: Tiia.Tamme @ kliinikum.ee

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