A periapical radiograph was obtained on a 38-year-old male (Figure 1). Tooth #9 has retained root tip. A roughly circular radiolucent lesion is present between the roots of teeth #6 and 7. The lesion has well defined and corticated border. Superimposed over the lesion are several irregular radiopacities. The lesion has resorbed the margins of both the incisors.
A histopathological examination was done, and the original diagnosis of the lesion was ameloblastic odontoma.
What is your diagnosis based on the radiograph?
The original diagnosis of ameloblastic odontoma was made before Dr. Robert Gorlin published his classic report of the calcifying odontogenic cyst. This periapical radiograph is the uncropped version of the radiograph published for case #13 in Dr. Gorlin’s paper.1
In 2005, Dr. Gorlin was cleaning his office in Moos Tower. He would bring some interesting images for my collection. One day he walked into my office with a pink envelope (Figure 2). With the usual twinkle in his eyes, he told me that this was the first calcifying odontogenic cyst radiograph that he had published. As I held the film in my hand, I knew it was a piece of history. Dr. Gorlin had published the paper in 1962. However, the envelope reminds us that the image was obtained in October 15, 1956. On the envelope, Dr. Gorlin crossed out his original diagnosis of ameloblastic odontoma and scribbled “calc. odont cyst.” As we now know, the rest is history.
Calcifying odontogenic cyst was termed with several synonyms. Gorlin cyst is probably the most popular, at least here in Minnesota. Other names for this lesion were calcifying ghost cell odontogenic tumor, cystic calcifying odontogenic tumor, keratinizing ameloblastoma, peripheral odontogenic tumor with ghost cell keratinization, and calcifying epithelial odontogenic cyst.
Currently, WHO classifies the lesion as a benign tumor and calls it calcifying cystic odontogenic tumor.2 This is now defined as “a benign cystic neoplasm of odontogenic origin, characterized by an ameloblastoma-like epithelium with ghost cells that may calcify”. In a paper published in 2008 in which Dr. Gorlin is an author, the lesion is reviewed in detail.3 Although several classifications exist, Dr. Gorlin’s recent paper classifies the lesion into four types.
• Type 1. Simple cystic CCOT. Includes pigmented and clear cell variants.
• Type 2. Odontoma-associated CCOT.
• Type 3. Ameloblastomatous proliferating CCOT.
• Type 4. CCOT associated with benign odontogenic tumors other than odontoma.
Calcifying cystic odontogenic tumor may occur in either jaw. About 20 to 50% of lesions are associated with a tooth. It often displaces tooth, and may cause root resorption (Figure 3). As shown in this panoramic radiograph, a small area of calcification is present between the roots of the premolars. Presence of calcifications inside the lesion is a hallmark. Radiographically, the lesion may be a corticated or ill-defined expansile mass (Figure 4). This axial section through the maxilla shows large expansion buccally, and smaller expansion palatally. Some lesions may appear multi-locular. Mostly the lesion is intraosseous, but can also be extraosseous. Calcifying cystic odontogenic tumor should be removed surgically and followed up for monitoring recurrence.
1. Gorlin RJ, Pindborg JJ, Clausen FP, Vickers RA. The calcifying odontogenic cyst — a possible analogue of the cutaneous calcifying epithelioma of Malherbe. An analysis of fifteen cases. Oral Surg Oral Med Oral Pathol 1962;15:1,235-43
2. Barnes L, Eveson J, Reichart P, Sidransky D, editors. Pathology and Genetics of Tumours of the Head and Neck. Lyon: IARC Press; 2005.
3. Ledesma-Montes C, Gorlin RJ, Shear M, Prae Torius F, Mosqueda-Taylor A, Altini M, et al. International collaborative study on ghost cell odontogenic tumours: calcifying cystic odontogenic tumour, dentinogenic ghost cell tumour and ghost cell odontogenic carcinoma.
J Oral Pathol Med 2008;37(5):302-8.
*Dr. Ahmad is Associate Professor in the Department of Diagnostic and Biological Sciences at the University of Minnesota School of Dentistry. He is a diplomate of the American Board of Oral and Maxillofacial Radiology.