Objective:

To highlight the diagnostic challenges posed by completely cystic submucosal leiomyomas and the critical role of histopathological examination in establishing a definitive diagnosis.

Approach:

• Case Presentation: A 42-year-old woman with irregular vaginal bleeding and lower abdominal pain underwent transvaginal ultrasonography, hysteroscopy, and immunohistochemical analysis.

Key Findings:

• The patient presented with a large cystic lesion in the uterine cavity, initially suspected to be an empty gestational sac.
• Negative serum β-hCG levels were crucial in ruling out pregnancy-related complications.
• Hysteroscopy allowed for direct visualization and excision of the cystic tumor, which was diagnosed as a completely degenerated cystic submucosal leiomyoma with focal proliferative activity confirmed by immunohistochemistry.

Interpretation:

This case illustrates the importance of considering cystic submucosal leiomyomas in the differential diagnosis of intracavitary cystic lesions, particularly when imaging suggests an empty gestational sac.

Limitations:

• The rarity of this presentation may limit generalizability to broader populations.
• The findings are based on a single patient experience, which may not represent typical cases.

Conclusion:

Hysteroscopy and immunohistochemistry are essential for accurate diagnosis and management of atypical presentations of leiomyomas.