The patient was a 26-year-old gravida 5, para 4 woman who underwent a bilateral tubal ligation via the Pomeroy procedure on postpartum day 1. Her obstetric history was significant for a first trimester spontaneous abortion requiring evacuation of the uterine cavity and 4 full-term spontaneous vaginal deliveries. She conceived her current pregnancy while using oral contraceptive pills. The pregnancy was complicated by subchorionic bleeding at 8 weeks, unexplained elevated α-fetoprotein at 15 weeks, preterm labor at 32 weeks, and an intrauterine fetal growth restriction. Her labor was induced at 39 weeks using oxytocin. A viable female infant weighing 2.610 kg was delivered vaginally without complication. The patient presented with no complaints and was doing well at her 6-week postpartum visit.

The surgical pathology laboratory received segments of the right and left fallopian tubes. The right fallopian tube segment measured 2.0 cm in length and 0.5 cm in diameter. The diameter of the lumen was approximately 0.1 cm. The left fallopian tube segment measured 2.2 cm in length and 0.5 cm in diameter. The diameter of the lumen was approximately 0.1 cm. The fallopian tube segments were fixed in formalin and then serially sectioned in approximately 0.3-cm intervals. No grossly identifiable lesions were seen on the external surface or within the lumen of either fallopian tube. The specimen was entirely submitted for paraffin embedding. The sections were stained with hematoxylin-eosin and examined by light microscopy. Cross sections from the left fallopian tube were stained with mucicarmine and the immunohistochemical stains cytokeratin (AE 1/3), epithelial membrane antigen, and carcinoembryonic antigen.

Microscopic examination revealed an unremarkable right fallopian tube with thin, branching plicae. The left fallopian tube showed evidence of chronic salpingitis with thickened, attenuated plicae having focal decidualization. Within the lumen of the left fallopian tube was an exophytic, papillary lesion (Figure, A; hematoxylin-eosin, original magnification ×50). The lesion was present in 2 of the 5 cross sections and measured approximately 0.2 cm in greatest dimension. The papillary cores were composed of loose, edematous connective tissue with occasional small vessels, sparse lymphocytes, and rare neutrophils (Figure, B; hematoxylin-eosin, original magnification ×200). The papillae were lined by a simple columnar epithelium with occasional pseudostratification. The majority of the epithelial cells were regularly spaced with elongated nuclei, vesicular chromatin, and abundant eosinophilic cytoplasm (Figure, C; hematoxylin-eosin, original magnification ×400). Some of the epithelial cells contained mucin-filled vacuoles that expanded to form cystlike spaces (Figure, D; mucicarmine, original magnification ×200). Focal disruption of the basement membrane led to extravasation of mucin into the papillary cores. Mitotic figures were absent. The epithelial cells were positive for cytokeratin (AE 1/3) and epithelial membrane antigen and negative for carcinoembryonic antigen.

What is your diagnosis?

This is a case of a papillary tumor of the fallopian tube with oncocytic and mucinous metaplasia. The lesion was an incidental histologic finding in a postpartum tubal ligation specimen. To our knowledge, 8 additional cases have been reported in the literature.

Saffos et al1 first reported 4 cases of metaplastic papillary tumor of the fallopian tube. All of these cases occurred in young, multiparous women (age, 27–33 years) undergoing postpartum tubal ligations after uncomplicated pregnancies. None of these patients had a significant gynecologic history or recent history of oral contraceptive use. On microscopic examination of each case, a unilateral, exophytic, papillary lesion with a loose connective tissue core and a columnar-to-pseudostratified epithelial lining was found. The epithelium showed focal stratification, but mitoses and significant cellular atypia were absent. The epithelial cells had large, oval nuclei with vesicular chromatin and occasional nucleoli. Many cells had abundant eosinophilic cytoplasm. Intracytoplasmic mucin vacuoles were present, and extracellular mucin was seen both on the luminal surface of the papillae and within the intraepithelial cysts. Two of the patients underwent subsequent total abdominal hysterectomy and bilateral salpingo-oophorectomy, 1 patient was closely monitored without subsequent surgery, and 1 patient was lost to follow-up. None of the followed patients had residual or recurrent disease, and all were alive and well for up to 6 years after the initial diagnosis.

Four additional cases have been reported. Two cases occurred in young, multiparous women undergoing postpartum tubal ligation.2,3 These reports further characterized the epithelial lining by immunohistochemistry and/or electron microscopy. They found that epithelial cells were positive for cytokeratin and epithelial membrane antigen and negative for carcinoembryonic antigen. The ultrastructural findings included cuboidal cells with microvilli, occasional cilia, and abundant cytoplasmic mitochondria. No clinical follow-up was available for one of these patients; the other patient was alive and well after 4 years. An additional case was reported as an incidental finding in a 52-year-old woman who presented with bilateral hydrosalpinx and ectopic pregnancy.4 This case is notable for the older age of the patient and for the potential association with ectopic pregnancy. The other case was reported in 1978, before the initial description of this entity. Although it was diagnosed as a grade I adenocarcinoma at that time, a subsequent review of this lesion found it to be more consistent with a metaplastic papillary tumor.5 Because of the malignant diagnosis, this patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. No residual or metastatic disease was found at the time of hysterectomy, but the long-term follow-up for this patient is unknown. This case highlights the importance of recognizing this lesion in order to avoid a malignant diagnosis.

The fallopian tube epithelium can undergo metaplastic, hyperplastic, and neoplastic changes.6 Reported metaplastic changes have included squamous metaplasia, oncocytic metaplasia, and mucinous metaplasia.6 These changes have been found both with and without associated tubal inflammation or history of the use of exogenous hormones. A recent review of the histologic findings in 287 fallopian tube specimens revealed metaplastic changes in 4.2%, including 11 cases of oncocytic metaplasia and 1 case of mucinous metaplasia.7 Hyperplastic or proliferative epithelial changes have also been reported in association with tubal inflammation, especially tuberculous infection, and exogenous estrogen exposure. Moore and Enterline8 described proliferative epithelial changes, including focal nuclear crowding, stratification, and papillae formation, in 23 of 124 fallopian tube specimens. In the review by Hunt and Lynn,7 stratification was present in 3.5% of the cases. Many studies have shown mitotic activity to be virtually absent in metaplastic and proliferative lesions. Neoplastic changes in the fallopian tube are very rare, with benign neoplasms less common than malignant neoplasms. Primary malignant tumors of the fallopian tube account for less than 1% of gynecologic malignancies and are defined by marked cytologic and architectural atypia, mitoses, invasion, and metastasis.6 

A metaplastic papillary tumor of the fallopian tube is a lesion characterized by papillary growth, oncocytic and mucinous metaplasia, and lack of atypia, invasion, or mitoses. All reported cases have had indolent clinical behavior with lack of recurrence and metastasis; consequently, this lesion should be considered benign. Debate exists about whether this lesion represents a benign tumor or a metaplastic process. Supporters of metaplasia focus on the mucinous and oncocytic metaplasia characteristics of this lesion and the association with physiologic states, such as pregnancy and inflammation. In contrast, supporters of benign neoplasia focus on the papillary architecture and the morphologic similarity of this lesion to benign tumors of the ovary.1 While the true histogenesis of this tumor remains unclear, it is important to identify this lesion, to recognize it as benign, and to report it to clinicians as such.

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Author notes

Corresponding author: Virginia A. LiVolsi, MD, Department of Surgical Pathology, University of Pennsylvania Medical Center, 3400 Spruce St, F6.056, Philadelphia, PA 19104 ([email protected])