Philipsen first described odontogenic keratocyst (OKC) in 1956. In 2005, the World Health Organization (WHO) termed it as keratocystic odontogenic tumor, a benign unilocular or multilocular intraosseous tumor with odontogenic origin, histologically multilayered parakeratinized stratified squamous epithelium lining and possessing the potential for aggressive and infiltrative behavior. In 2017, the WHO reclassified it from a tumor to a cyst. It is a cyst of epithelial development, arising from the remnants of the dental lamina, retained in the alveolar bone during tooth formation or subsequent proliferation of posttraumatic implantation of the basal oral epithelial layer. It is named as keratocyst, since the cyst lining produces keratin material.
It is mostly seen in 10–40 years of age, predominately among males and mainly involving the mandible. Presenting features include pain, facial asymmetry or swelling, bone expansion, discharging sinus, or numbness/tingling of the lip and teeth. Surgical resection is the only treatment available. The conservative surgical approach involves marsupialization and enucleation with or without curettage. An aggressive approach would involve peripheral ostectomy, curettage supplemented with Carnoy’s solution, and en bloc resection. Our case is unique as it was a large maxillary parakeratinized OKC in a female and was managed with marsupialization and enucleation with peripheral ostectomy without resorting to complete maxillary resection and with no recurrence in the last 3 years.
A 21-year-female presented to our outpatient clinic with swelling of the right part of the face for 1 year. The swelling did not cause any pain but was progressively increasing in size. She had suffered blunt trauma on the right side of the face 5 years back, with no history of fracture or any treatment sought at that time. There was no history of nose block, discharge, or bleeding from the nasal or oral cavity, neither any loosening nor loss of teeth. She had no history of difficulty in chewing food or articulation. On examination, there was a 5 cm × 4 cm bony hard swelling in the right maxillary region, obliterating the nasolabial fold [Figure 1]. The examination of the oral cavity did not show any abnormal displacement of the tooth or bulge on the alveolus or hard palate.
A noncontrast computed tomogram of the maxilla-facial area revealed a 4.3 cm (superior-inferior) × 3.6 cm (medial-lateral) × 2.9 cm (anterior-posterior), well-defined lytic expansile lesion, arising from the maxillary alveolus of the right side and bulging into the floor of the right maxillary sinus, partially obliterating its lumen [Figure 2]. The lesion was filled with a mixed-density fluid and had caused expansion and thinning of both lingual and buccal cortexes with multifocal full-thickness defects. Fine-needle cytology from the lesion demonstrated benign epithelial cells and cystic macrophages in a proteinaceous background, suggesting a benign cystic lesion.
Under general anesthesia, the lesion was approached via the right sublabial route, the mucoperiosteal flap was elevated [Figure 3], and the thin bone overlying the cyst was fractured and removed piecemeal. The straw-colored fluid contents of the cyst were aspirated to decompress it. The capsule of the cyst was raised from the bone, and the cyst was excised completely [Figure 4]. The bony wall of the cyst was subjected to mechanical curettage using a micromotor drill. The cavity was connected with the maxillary sinus and medicated ribbon gauze was packed, with its loose end brought in the nasal cavity after endoscopic middle meatal antrostomy, the preferred drainage pathway of the maxillary sinus. It is stressed here that the healthy maxillary sinus mucosa was preserved, unlike Caldwell-Luc, where diseased maxillary sinus mucosa is stripped and inferior meatal antrostomy was done for drainage. The wound was closed by inverting, interrupted absorbable suture. The pack was removed after 48 h via the nostril. The final histopathology reported a fibrocollagenous cyst wall lined by 2–4-layer-thick parakeratinized stratified squamous epithelium, which is ulcerated at places and subepithelium showing granulation tissue with chronic inflammatory infiltrate. This was compatible with the diagnosis of OKC, a parakeratinized variant. There is no recurrence of the cyst in the last 3-year follow-up.
OKC commonly occurs in the posterior body and ramus of the mandible. Rarely, they may develop in the maxilla, frequently in the incisor-canine region as in our case. They are often painless swelling with potential for local destruction and, occasionally, may present with pain and secondary infection. They may occur following trauma, as in our case, due to implantation of the basal cell layer of the surface epithelium. They expand due to forces exerted on the surrounding tissue, by the fluid secreted from the epithelium and because of enzymatic activity by the fibrous wall.
The OKCs are aggressive in nature and have a high rate of recurrence due to a variety of local factors such as collagenase production, matrix metalloproteinases, interlukin-1 alpha, parathyroid hormone-related protein, Bcl-2, and cytokeratin 10 and additionally the presence of satellite cysts or occasionally an incomplete removal.[1,7] There is histologic evidence that the overlying mucosa may lead to recurrence, hence its removal has been recommended. However, in our case, there was no visible connection with alveolar mucosa. Evidence suggests that the parakeratinized variant has more aggressive behavior and a higher recurrence rate as compared to orthokeratinized.
Radiological appearance may differ; it may be a unilocular lesion to a large multilocular radiolucent mass, similar to an ameloblastoma, a dentigerous, lateral periodontal, or radicular cyst. Usually, OKC has identifying features of being unilocular with smooth borders, without adjacent tooth displacement or unerupted tooth or root resorption. Multiple OKCs may exist in nevoid basal cell carcinoma syndrome (NBCCS), referred to as Gorlin-Goltz syndrome. Besides nevoid basal cell carcinomas, these patients may have frontal bossing, bifid ribs, epidermoid cysts, falx cerebri calcification, and medulloblastoma.
The marsupialization and enucleation may have a high recurrence rate (25%–50%). More aggressive treatment includes complete resection supplemented with Carnoy’s solution (chloroform, absolute alcohol, ferric chloride, and glacial acetic acid) with or without peripheral ostectomy, which has a lower recurrence rate (10%).[12,13] The aggressive technique is recommended in patients with NBCCS, large OKC, and recurrent lesions. In our case, we used mechanical curettage using a rotary microdrill with cutting burr for peripheral ostectomy to ensure complete removal of cyst lining. This procedural technique provides a safety margin, helps in smoothening the walls, and eliminates any residual cystic epithelium. Thus, our case highlights how a large maxillary parakeratinized OKC in a female can be managed with marsupialization and enucleation with peripheral ostectomy which is a much lesser aggressive surgical technique ensuring complete resection without resorting to downright maxillary bone resection. Fortunately, there has been no recurrence in the last 3 years.
This case highlights the successful management of a large maxillary OKC parakeratinized variant in a young female. These cysts may be asymptomatic during the initial stages as they are slow growing. They may mimic other cystic tumors closely, therefore a careful radiological and histopathological evaluation is required. These also have a high rate of recurrence, thus they should be treated aggressively and followed up periodically.
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