Incidence
Endosalpingiosis was found in 2.4% (n=287) of surgically removed fallopian tubes [5]. In a retrospective study of 51 women undergoing laparoscopy for chronic pelvic pain, 11.8% demonstrated endosalpingiosis. In all six cases, endosalpingiosis was found in locations consistent with the patients’ pelvic pain [6]. In a recent study [7], 7% of premenopausal women undergoing laparoscopy were diagnosed with endosalpingiosis.
Pathology
Endosalpingiosis is characterised by the presence of glands lined by ciliated tubal-type epithelium. It is usually an incidental finding, often occurring in association with ovarian serous neoplasms. Occasionally, it may form a tumour-like mass that has been called “florid cystic endosalpingiosis” [8]. It is a benign condition, but atypical epithelial changes have been reported and appropriately named “atypical endosalpingiosis”.
The diagnosis of endosalpingiosis is made histologically by the presence of tube-like epithelium containing three types of cells: ciliated columnar cells, nonciliated columnar secretory mucous cells and so-called intercalary or peg cells in an ectopic location. Macroscopically, endosalpingiosis may be composed of simple cysts or may demonstrate a more complex papillary architecture. Microscopically, inclusions of the latter type have been associated with psammoma bodies [9]. Stroma is absent, and it generally is not hemorrhagic (Fig. 1).
Differentiation from endometriosis
Endometriosis is characterised by the presence of endometrial glands and stroma. It often has a hemorrhagic appearance as a result of the tissue’s response to a hormonal stimulus. The psammoma body, although not specific to endosalpingiosis, is not a feature of uncomplicated endometriosis and therefore can be of diagnostic value (Fig. 2).
Differentiation from ovarian papillary serous tumours
Both may have psammoma bodies and endosalpingiosis may form a papillary configuration, “atypical endosalpingiosis”, as a result of irritation, manipulation or trauma. Features supporting the diagnosis of ovarian papillary serous tumour include desmoplastic stromal response, presence of only one cell type, an infiltrative pattern and an absence of a basement membrane surrounding the glands [10].
Theories on development
The various hypotheses for the pathogenesis of endosalpingiosis are similar to those of endometriosis. Kistner described five theories on the pathophysiologic mechanisms of endometriosis: (1) transplantation: tubal mucosa is transplanted to peritoneal surfaces during surgery; (2) direct extension: tubal epithelium extends to the peritoneum by adhesions; (3) coelomic metaplasia: coelomic peritoneal cells are multipotential and can differentiate into oviduct epithelium; (4) reactive: salpingitis with excessive tubal proliferation during the repair process; (5) metastasis: by lymphatic-vascular spread. These theories are not exclusive, and several mechanisms may be responsible.
The natural history of endosalpingiosis is unclear, although calcification and eventual resorption is the usual course. This explains the high incidence of psammoma bodies associated with the lesion. Since endosalpingiosis is rare in children and postmenopausal women, it is thought to develop after menarche and undergo atrophy in the postmenopausal years. Furthermore, spontaneous regression of peritoneal lesions has been reported after removal of an associated ovarian tumour, suggesting a hormonal dependence [11].
Sites of disease
Endosalpingiosis is typically found in the visceral pelvic peritoneum covering the uterus, fallopian tubes, ovaries and cul-de-sac. Less frequent locations involve the pelvic parietal peritoneum, omentum [12], bladder [5] and bowel serosa [13], periaortic area and within the skin [14].
Significance of endosalpingiosis
Despite earlier suggestions by Sampson [15] and Everett that endosalpingiosis may spread quite aggressively, it has created little interest. It is presumed to be an asymptomatic benign entity found incidentally and associated with conditions such as salpingitis, endometriosis and serous tumours. Only a couple of case reports suggest an association between endosalpingiosis and pelvic pain. A retrospective study by Keltz [6] of 51 laparoscopies for pelvic pain found six cases of endosalpingiosis in locations associated with the patient’s pelvic pain, and all obtained relief after surgery. This suggests that endosalpingiosis may not be an incidental finding in pelvic pain. It may be overlooked since it often coexists with endometriosis, and the majority of surgeons treating endometriosis ablate lesions, never obtaining a histologic diagnosis.
Endosalpingiosis in lymph nodes, sometimes referred to as benign glandular inclusion and müllerian nest, is well recognised as a potential mimic of metastatic neoplasm. Distinguishing “atypical endosalpingiosis” from an extraovarian serous borderline tumour or borderline implants may be difficult and may pose serious diagnostic problems.
Peritoneal washing cytology is an adjunct in the surgical pathological evaluation of gynaecological malignancy. There are several reported cases in which endosalpingiosis has created diagnostic problems, particularly when the cytologist is unaware of the morphology of the primary tumour [16, 17, 15].
As previously mentioned, endosalpingiosis may be associated with ovarian epithelial neoplasms, especially borderline or well-differentiated lesions [19, 20, 21]. It has also been found in association with cervical carcinoma [16, 17].
There is controversy about the hypothesis that ovarian epithelial tumours arise from the single cell layer lining the ovarian surface. This theory fails to explain the morphological resemblance of tumours found outside the ovary that are identical to ovarian carcinomas. Further, it fails to explain why some ovarian tumours resemble tumours derived from the Müllerian ducts, such as the fallopian tubes, endometrium and endocervix. The alternate hypothesis is that components of the secondary Müllerian system, which includes endosalpingiosis, endometriosis, paraovarian/paratubal cysts, rete ovarii and endocervicosis, may play a role in tumourigenesis [22]. The possibility of malignant change of endosalpingiosis must be considered, analogous to carcinoma arising in endometriosis. In endosalpingiosis, the tubal nature of the epithelium may be obscured by cell flattening in an expanding cyst or be distorted by proliferating cells. The end of the spectrum is a serous cystadenocarcinoma of the ovary, or more rarely, a papillary carcinoma of the peritoneum. Although the incidence of this malignant transformation is not known, it is important to evaluate each focus of endosalpingiosis.
Presentation
Endosalpingiosis usually is an incidental microscopic finding, often occurring in association with ovarian serous neoplasms. It is generally not recognised by gynaecologists at the time of laparoscopic evaluation or is misdiagnosed as endometriosis. Macroscopically, this disease is usually not discernable. When it is visually obvious, endosalpingiosis can be seen as multiple white to yellow, translucent to opaque, punctate, fluid-filled cystic lesions [20].
Patients with endosalpingiosis are often asymptomatic, while those with endometriosis and endocervicosis more commonly experience symptoms [23].
Management
Medical management for endosalpingiosis with gonadotrophin-releasing hormone analogue has been used with variable success. Malignant degeneration has been documented in conjunction with endocervicosis, and surgical resection has been recommended for bladder lesions of müllerian origin [5].