Residual Cyst
A radicular cyst that persists within the jaw following extraction of the causative non-vital tooth, presenting as a well-defined radiolucency in an edentulous area.
Full Definition
A residual cyst develops when a radicular cyst is incompletely removed or overlooked at the time of tooth extraction, allowing the epithelium-lined cavity to persist and potentially enlarge. Radiographically, it appears as a well-defined, often corticated unilocular radiolucency in a site where no tooth root is present. It is among the differential diagnoses that must be considered for any unexpected radiolucency in an edentulous region. Editors must distinguish 'residual cyst' from 'radicular cyst' — the qualifier 'residual' is clinically and terminologically significant and should not be omitted.
Usage
Usage note: The word 'residual' is not interchangeable with 'retained' in this context. A residual cyst is not merely retained tissue; it is a cyst with its own growth potential.
In Context
- "A 15 mm well-defined radiolucency was identified in the right mandibular molar region, a site where the tooth had been extracted five years previously, raising suspicion of a residual cyst." — Panoramic radiograph report
- "The patient's records confirmed no prior enucleation at the site, supporting the diagnosis of a residual cyst rather than surgical defect." — Oral surgery case note