A 19-year-old woman has noted swelling in the back of her mouth for 2 months. On dental examination, she has an area of swelling in the location of the left third molar. Dental radiographs show a radiolucent unilocular, well-circumscribed cyst surrounding the crown of the unerupted third mandibular molar. The lesion is excised, and on microscopic examination, the cyst is lined by stratified squamous epithelium and surrounded by a chronic inflammatory infiltrate. What is the most likely diagnosis?
A 19-year-old woman has noted swelling in the back of her mouth for 2 months. On dental examination, she has an area of swelling in the location of the left third molar. Dental radiographs show a radiolucent unilocular, well-circumscribed cyst surrounding the crown of the unerupted third mandibular molar. The lesion is excised, and on microscopic examination, the cyst is lined by stratified squamous epithelium and surrounded by a chronic inflammatory infiltrate. What is the most likely diagnosis?
💡 Explanation
**Core Concept:** A cyst is a fluid-filled sac that forms within body tissues, often due to the persistence of a developmental structure or a response to an irritant. In dentistry, cysts can occur around developing teeth, with radiotransparent unilocular cysts being more common. The described radiographic appearance and microscopic examination findings align with a **RadioLucent Unilocular Cyst (RUC)**.
**Why the Correct Answer is Right:** The correct answer is **Dental Follicular Cyst (DFC)** as it is the most likely diagnosis in this scenario. Dental follicular cyst develops from the epithelial remnants of the dental follicle, surrounding the crown of the unerupted tooth. The cyst lining consists of stratified squamous epithelium, and the inflammatory infiltrate surrounding the cyst indicates an immune response to the cyst formation.
**Why Each Wrong Option is Incorrect:**
A. **Odontogenic Keratocyst (OKC)** typically presents as a multilocular, expansile radiolucency and has a higher recurrence rate after treatment compared to DFC.
B. **Amenorrhea-hypothalamic amenorrhea (AHA)** is a hormonal disorder, unrelated to dental cysts.
C. **RadioLucent Unilocular Cyst (RUC)** is a more general term for the described cyst, but does not specify the cause.
**Clinical Pearl:** The microscopic examination of a cyst is essential for accurate diagnosis, as the presence of a chronic inflammatory infiltrate around the cyst wall helps differentiate dental cysts from other cyst types, like AHC, which do not typically have this feature.
✓ Correct Answer: B. Dentigerous cyst
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