Fallopian Tube Tumors: Benign and Malignant Types
Fallopian tube tumors are classified according to the WHO 2014 classification system, with the vast majority being malignant epithelial tumors (predominantly high-grade serous carcinoma), while benign tumors are uncommon and most frequently adenomatoid tumors of mesodermal origin. 1
Benign Fallopian Tube Tumors
Benign tumors of the fallopian tube are rare and typically small incidental findings at surgery 2:
- Adenomatoid tumor: The most common benign tumor of the fallopian tube, of mesodermal origin 3
- Lipoma: Rare benign mesodermal tumor that may contain Morgagni hydatid cysts 2
- Other benign mesodermal tumors (uncommon) 2
These benign lesions are usually small enough to be discovered incidentally during laparotomy rather than causing clinical symptoms 2.
Malignant Fallopian Tube Tumors
The WHO classification of primary epithelial tumors of the fallopian tube includes 1:
Epithelial Precursor Lesion
- Serous tubal intraepithelial carcinoma (STIC): The precursor lesion for high-grade serous carcinoma 1
Borderline Tumors
- Serous borderline tumor/atypical proliferative serous tumor 1
Malignant Epithelial Tumors
High-grade serous carcinoma is by far the most common primary tubal malignancy 1:
- High-grade serous carcinoma (HGSC): The predominant type, representing the vast majority of primary tubal carcinomas 1
- Low-grade serous carcinoma: A distinct tumor type with different pathogenesis and molecular alterations compared to HGSC 1
- Endometrioid carcinoma: The second most common type after serous carcinomas 1
- Undifferentiated carcinoma: High-grade tumor 1
- Mucinous carcinoma: Rare 1
- Transitional cell carcinoma: Rare 1
- Clear cell carcinoma: Rare, high-grade tumor 1
Mixed Epithelial-Mesenchymal Tumors
- Carcinosarcoma (malignant mixed Müllerian tumor): Extremely rare in the fallopian tube, with only 37 cases reported in the literature as of 1992 4
Clinical Context and Prognostic Considerations
Most primary tubal carcinomas are high-grade serous or endometrioid types 1. The distinction between low-grade and high-grade serous carcinoma is critical because these represent different tumor types with distinct pathogenesis, molecular alterations, and prognosis rather than simply different grades of the same tumor 1.
Important Clinical Distinctions:
- HGSC may be associated with BRCA1/2 mutations, making accurate tumor typing important for identifying genetic predisposition 1
- Endometrioid and clear cell carcinomas can occur in patients with Lynch syndrome 1
- Endometrioid carcinomas of the fallopian tube are characteristically noninvasive or only superficially invasive with generally favorable prognosis, particularly when confined to Stage I disease 5
- Carcinosarcomas have poor prognosis, with the most important prognostic factor being tumor spread at diagnosis 4
Diagnostic Challenges:
Correct preoperative diagnosis of fallopian tube tumors is difficult, as clinical features often mimic primary ovarian carcinoma 4. Tubal cytology using fallopian tube brushings may be useful for screening and early detection, with three-dimensional clusters and prominent nucleoli highly correlated with malignancy 6.