|Year : 2015 | Volume
| Issue : 2 | Page : 82-85
Radicular Cyst with Squamous Odontogenic Tumor-like Proliferation: An Unusual Entity
Anitha Dayakar, Harishchandra Rai, PD Suhasini, Charan Kaje
Department of Oral Pathology and Microbiology, KVG Dental College, Sullia, Karnataka, India
|Date of Web Publication||17-Dec-2015|
Department of Oral Pathology, KVG Dentall College, Kurunjibagh, Sullia, Karnataka
Source of Support: None, Conflict of Interest: None
Squamous odontogenic tumor-like proliferation (SOT-LP) is a nonneoplastic lesion with a histological pattern similar to that of the SOT. This entity is characterized by SOT proliferations isolated in the cyst wall of an odontogenic cyst. This pattern is rarely seen in radicular cysts. The nature of these proliferations is not clear, and there is a varied opinion on the origin. Although it has a benign behavior, it should be differentiated from other aggressive lesions such as intraosseous carcinoma, ameloblastoma, odontogenic keratocyst, and SOT. Knowledge about this unusual lesion can help in the accurate diagnosis and treatment of the patients. Here, we are discussing a rare case of an SOT-LP emerging in a radicular cyst of the maxilla.
Keywords: Ameloblastoma, radicular cyst, squamous cell carcinoma, squamous odontogenic tumor
|How to cite this article:|
Dayakar A, Rai H, Suhasini P D, Kaje C. Radicular Cyst with Squamous Odontogenic Tumor-like Proliferation: An Unusual Entity. Indian J Oral Health Res 2015;1:82-5
|How to cite this URL:|
Dayakar A, Rai H, Suhasini P D, Kaje C. Radicular Cyst with Squamous Odontogenic Tumor-like Proliferation: An Unusual Entity. Indian J Oral Health Res [serial online] 2015 [cited 2019 Jun 15];1:82-5. Available from: http://www.ijohr.org/text.asp?2015/1/2/82/172046
| Introduction|| |
Squamous odontogenic tumor-like proliferations (SOT-LPs) is an uncommon histological finding occurring in the walls of odontogenic cysts. This entity has been interpreted as a nonneoplastic, reactive process that is secondary to the cyst formation or inflammation.  Microscopically, the SOT-LPs share certain histological features with SOT. It is important to distinguish between these two pathologic conditions because of differences in their biological behavior.  Histopathologic features of SOT-LPs in odontogenic cysts bear a close resemblance to not only SOT but also to acanthomatous ameloblastoma, desmoplastic ameloblastoma, odontogenic keratocyst, and well-differentiated squamous cell carcinoma. This fact is of major importance. Thus, misinterpretation of the microscopic features of the SOT-LPs can result in significant errors in treatment. 
| Case report|| |
A 21-year-old female patient reported to our institution with a complaint of fractured teeth in the upper front tooth region. The patient gave a history of a fall 10 years back. On intraoral examination, fractured maxillary central incisors were noticed [Figure 1]. The occlusal radiograph revealed a radiolucent area extending from an apical third of 21 to the level of 26 [Figure 2]. The lesion was measuring 2 × 1 cm in diameter with a well-defined outline. The root apices of the central incisors were diverging with open apices. Clinically, a provisional diagnosis of the periapical cyst was given. Root canal treatment was done for both the central incisors. Apicoectomy of the affected teeth was performed under local anesthesia. The lesion was removed and sent for histopathological examination.
|Figure 2: Occlusal radiograph showing radiolucent lesion extending from apical third of 21 to the level of 26|
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Microscopically, hematoxylin and eosin stained sections showed a lining of the nonkeratinized stratified squamous epithelium of varying thickness with a discontinuity in some areas. Some areas of epithelium showed proliferation in arcading pattern. The connective tissue wall was made up of dense bundles of collagen fibers with moderate to dense inflammatory response consisting of lymphocytes and plasma cells. Numerous islands of epithelial cell proliferations forming rounded aggregates were seen in the connective tissue capsule [Figure 3] and [Figure 4]. No cellular atypia was noticed [Figure 5]. Although the epithelial islands resembled satellite cysts, none of the areas showed a lining typical of odontogenic keratocyst. The histopathological diagnosis of the radicular cyst with SOT-LPs was made.
|Figure 3: Discontinuous epithelial lining with islands of epithelial cell proliferations (H and E, original magnification ×10)|
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|Figure 4: Epithelial islands of varying size in the connective tissue wall (H and E, original magnification ×10)|
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|Figure 5: Absence of cellular atypia (H and E, original magnification ×20)|
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The postoperative intraoral periapical radiograph showed adequate root canal filling for both central incisor and left lateral incisor [Figure 6]. The patient is under regular follow-up of 6 months without any recurrence.
| Discussion|| |
Radicular cysts show distinct histopathological findings. They may be lined continuously or partly by nonstratified squamous epithelium and surrounded by a fibrous connective tissue capsule. A few unexpected neoplasms such as intraosseous squamous cell carcinoma have also been reported in the periapical tissue. This is an important insight into the cognition of the histological variations of radicular cysts.  SOT-LP is an uncommon histological finding which shows multiple islands of squamous odontogenic epithelium in the cystic wall and thus, resembles the "true SOT." 
Its nature is not clear and there is a varied opinion regarding the origin. According to Shear and Speight, the SOT-LP epithelium in radicular cyst originates from the rests of Malassez.  Unal et al. considered the SOT-like epithelial island to be "hamartoid," however, others have disputed this theory because of the proposed origin of SOT-LPs from a cystic surface.  Philipsen et al. believe that the SOT-LPs are a result of a reactive, inflammatory hyperplasia of the epithelial cyst lining.  Odell and Morgan favor a budding type of hyperplasia of the lining epithelium of radicular cysts and attribute it to a response to subsiding inflammation because it usually occurs in areas without inflammation.  The role of inflammation remains uncertain because SOT-LPs are not limited to inflammatory cysts, but also have been reported in developmental cysts including the dentigerous cysts and the odontogenic keratocyst. 
Parmar et al. reviewed 1241 radicular cysts and reported a prevalence of 3.4%, the highest incidence of the lesion was found to be in the 5 th and 6 th decades. There were a maxillary predilection and incisors, including cuspids were most often involved.  In the present case, the patient was a 21-year-old female and the lesion was in the maxillary incisor area.
Santos et al. have done a study to investigate the histopathological features of radicular cysts diagnosed in a Brazilian population. Out of 73 cases, 3 cases showed epithelial plaques resembling SOT. 
Histologically, the SOT-LPs present as a cystic cavity, partially lined by stratified squamous epithelium. In the fibrous capsule, a focus of mild chronic inflammation and multiple epithelial islands are seen. Islands do not show cellular atypia. 
SOT-LPs possess certain histopathological features that overlap with several neoplasms including SOT, acanthomatous ameloblastoma, desmoplastic ameloblastoma, intraosseous squamous cell carcinoma, and infected odontogenic keratocyst, with which they should be differentiated. 
SOT and SOT-LP are histologically very similar, with the presence of aggregates of well differentiated and nonkeratinized squamous odontogenic epithelial cells surrounded by fibrous connective tissue in both the entities.  SOT may arise from either epithelial rests of Malassez, gingival surface epithelium or remnants of dental lamina. Inflammatory stimuli do not seem to be involved in the initiation of SOT in contrast to SOT-LP observed in the odontogenic cyst.  Definitive criteria for differentiating this reactive proliferation from the neoplastic process have not been established, but Melrose indicates that the reactive islands seldom form microcysts or contain intraepithelial calcification.  SOT-LP exhibits varying clinical, radiological, and prognostic features than true SOTs. Biologically, SOTs are less aggressive than ameloblastomas but are more aggressive than SOT-LP in the cysts. 
Ameloblastomas typically possess islands demonstrating peripheral columnar cell differentiation with reverse polarization and optically clear cytoplasm. In contrast, SOT-LP islands are bordered by flattened to cuboidal basaloid cells with no stellate reticulum like cells. 
Islands of squamous cell carcinoma manifest cytological atypia including altered nuclear, cytoplasmic ratio, nuclear hyperchromatism, and mitotic activity with abnormal mitosis.  SOT-LP islands do not show cytological atypia.
Odontogenic keratocysts show a parakeratinised cystic lining with the remarkable uniformity of the thickness of the epithelium. A prominent palisaded a polarized basal layer of the cells having a "picket fence" or "tombstone" appearance is also a distinguishing feature.
The management of SOT-LP comprises of enucleation, curettage, or local excision of the lesion.  Reactive foci of SOT within the connective tissue wall of odontogenic cysts do not seem to alter the prognosis of the primary cystic process.  The SOT-LPs in radicular cysts do not represent an early expression of neoplastic transformation. Till date, there have been no reports of recurrences or malignant changes in the literature relating to odontogenic cysts with SOT-LP. However, it is important to differentiate it from other similar appearing aggressive lesions.
| Conclusion|| |
The apical soft tissue lesion should be evaluated histopathologically, not to distinguish a cyst versus granuloma, but to rule out unexpected neoplasms or more aggressive cysts. Most clinicians discard periapical tissue after a surgical procedure rather than sending it for histopathologic evaluation, thus missing potentially valuable information. It is emphasized that all periapical lesions should be carefully evaluated to exclude malignant changes. Knowledge about SOT-LP in odontogenic cysts can prevent misdiagnosis and ensure accurate treatment.
| Acknowledgment|| |
We express our gratitude to all staff members.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]