Residual cyst of the jaws: A clinico-pathologic study of this seemingly inconspicuous lesion

OBJECTIVES: Residual cysts are relatively rare inflammatory cysts of the jaws. They are essentially radicular cysts without the presence of the offending dentition. These lesions have the ability to destroy bone within the jaws without any symptoms. Moreover, they can mimic more aggressive cysts and tumours on radiographs. The aim of this study was to describe the clinico-pathological features of residual cysts in order to discern them from other cystic lesions as well as analyse their management and recurrence patterns. MATERIALS AND METHODS: Sixty-four histopathologically confirmed residual cysts were analysed based on their clinical, radiological and histopathological features. Their management and follow-up were also noted. RESULTS: The majority of lesions presented in elderly (46.8%), edentulous patients (60.9%) and were most commonly found in the posterior regions of the mandible (51.6%). Clinico-pathological features that aided in their diagnosis included long-standing history with slow growing swelling and presence of well-defined, unilocular cystic lesion associated with previously extracted dentition. Enucleation was a successful method in the management of residual cysts with very low recurrence rate (1.6%). Two patients (3.1%) developed squamous cell carcinoma from the cyst lining. CONCLUSION: Residual cysts should be high on the list of differential diagnosis when elderly, edentulous patients present with cystic lesions in the jaws compared to dentate patients (P<0.01). All lesions should by biopsied and sent for histopathological examination along with radiological correlation as they have the potential to transform into primary intra-osseous squamous cell carcinoma with devastating consequences to the patient.