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residual cyst

Tuesday 10 May 2016


Definition: Inflammatory fibrous and granulation tissue at the apex/periapical region of a tooth not removed/curetted at the time of dental extraction may give rise to residual cyst. They represent 8% of all jaw cysts.


- Radiograph demonstrates radiolucent lesion in toothbearing region of jaws without a close association to the periapical region of tooth.
- Histology shows benign hyperplastic squamous epithelium.
- May or may not show spongiosis or acanthosis.
- Acute or chronic inflammation may be present.

Differential diagnosis

- unicystic ameloblastoma , inflamed
- odontogenic keratocyst , inflamed
- glandular odontogenic keratocyst , inflamed
- lateral periodontal cyst , inflamed
- maxillary surgical ciliated cyst , inflamed


Vast majority have excellent prognosis. True residual cysts do not recur after appropriate treatment and are not premalignant. They have no increased risk of squamous cell carcinoma.


Occasionally, a secondary pathology, such as squamous cell carcinoma, may arise from the epithelial lining of radicular cysts, or other odontogenic gnathic cysts. Careful patient questioning and clinical examination are necessary to exclude a primary oral mucosal neoplasm or metastases.

It is also needed to rule out an epithelial neoplasm which underwent secondary cystic change.

Histological evidence of cyst lining with transition to epithelial dysplasia and infiltrating squamous carcinoma provides acceptable proof.