What is a Nabothian Cyst?
A Nabothian cyst (also called a nabothian follicle or mucous retention cyst) is a benign, non-neoplastic mucinous cystic lesion of the uterine cervix that forms when cervical mucus accumulates inside blocked cervical glands or crypts. 1
Formation and Pathophysiology
- Nabothian cysts develop when the openings of cervical crypts become obstructed, leading to retention of cervical mucus within the blocked glands 1
- The obstruction typically occurs due to squamous metaplasia overlying the columnar epithelium of the endocervical glands, trapping mucus-producing cells beneath 1
- These are considered a normal physiologic finding rather than a pathologic condition 2
Clinical Characteristics
Typical Presentation
- Most commonly occur in women of reproductive age and are generally small (typically <1 cm) and asymptomatic 2, 1
- The cysts contain clear or yellowish mucinous fluid 3
- They are usually discovered incidentally during routine pelvic examination or imaging 4
- Multiple cysts can coexist, and individual cysts can reach up to 4 cm in size 2
Atypical Large Cysts
- Giant nabothian cysts (>4 cm) are extremely rare but have been reported up to 15 cm in diameter 3
- Large cysts may present with symptoms including chronic dyspareunia, pelvic pain, lower abdominal heaviness, or a sensation of something protruding from the vagina 1, 4
- In rare cases, very large cysts can obstruct the birth canal during labor 5
Diagnostic Approach
Imaging Characteristics
- Ultrasonography is the primary imaging modality, showing anechoic or hypoechoic cystic lesions with smooth walls and no solid components 2, 1
- MRI provides superior characterization for large or complex cysts, showing well-defined cystic masses with high T2 signal intensity 1
- The cysts typically appear as multiloculated or unilocular anechoic lesions on transvaginal ultrasound 4
Critical Differential Diagnosis
- The most important distinction is from adenoma malignum (minimal deviation adenocarcinoma), a rare mucin-producing cervical malignancy that can appear similar on imaging 2, 1
- Other differentials include cervical fibroids, endometriosis, and other cervical neoplasms 3
- Histopathologic confirmation is recommended for atypical presentations or cysts >4 cm to definitively exclude malignancy 2, 1
Management
Small Asymptomatic Cysts
- No treatment or intervention is required for typical small nabothian cysts, as they are benign and clinically insignificant 1
- Routine observation is appropriate 2
Large or Symptomatic Cysts
- Surgical excision is indicated for large cysts (>4 cm), symptomatic cysts, or when malignancy cannot be excluded 1, 3
- Laparoscopic excision is the preferred minimally invasive approach, allowing complete removal while avoiding unnecessary hysterectomy 1, 3
- Simple aspiration may be performed for acute obstruction (such as during labor), but definitive excision is typically needed as cysts often persist or recur 5
Common Pitfalls
- Do not assume all cervical cystic masses are benign nabothian cysts without proper imaging characterization, as adenoma malignum can be mistaken for a benign cyst 2, 1
- Large nabothian cysts can be misdiagnosed as malignant tumors on initial examination, leading to unnecessary radical surgery 2, 4
- Careful preoperative imaging with both ultrasound and MRI is crucial for large or complex cysts to avoid diagnostic errors 1
- In surgical cases, complete excision with histopathologic confirmation is essential to definitively rule out malignancy 1, 3