Splenosis Masquerading as Endometriosis: A Rare Pelvic Post-Trauma Presentation

Introduction

Splenosis is the ectopic autotrasplantation of viable splenic tissue onto any vascularized surface commonly following traumatic injury to the spleen or following splenectomy [1–5]. Splenosis is detected postoperatively in up to two-thirds of splenectomy patients with an average detection interval of 10 years [6]. Splenic implants are frequently multiple, range from millimeters to centimeters in diameter, and appear reddish-blue in color [7]. These implants can arise anywhere in the peritoneal cavity, likely by means of seeding, or are sometimes found extraperitoneally, likely due to hematogenous spread. Common sites include the abdomen and pelvis, but other atypical sites of implantation can occur including hepatic, intrathoracic, pericardial, subcutaneous, and even intracranial locations [8–13]. In a limited number of cases, concurrent intrathoracic and abdominal splenosis was also reported [14]. Splenosis can be asymptomatic and can be detected incidentally on imaging or intraoperatively. However, it can also present with a wide range of signs and symptoms depending on size and location which can render the diagnosis very challenging, thus triggering an extensive work-up of noninvasive and invasive procedures. Case reports of pelvic splenosis have been reported since 1939 [15–24] but more rarely in the gynecologic literature. Depending on symptomatology and location, it may be confused with primary uterine or ovarian masses or even endometriosis [16]. Given the diagnostic ambiguity of both splenosis and endometriosis, when symptomatology overlaps patients may undergo unnecessarily invasive procedures. We outline a case of pelvic splenosis presenting with the constellation of symptoms highly suggestive of endometriosis, including dysmenorrhea, deep dyspareunia, and infertility. We aim to increase awareness of this diagnostic dilemma for improved diagnosis and directed treatment.

Case Report

A 37-year-old gravida 1 para 0 woman was referred to the minimally invasive gynecologic surgery department for dysmenorrhea, deep dyspareunia, and infertility of 7 years duration. Her histories were significant for a motor vehicle accident >10 years prior requiring exploratory laparotomy and splenectomy. On pelvic exam, she had bilateral levator spasm and a diffusely tender uterus with no retrocervical tenderness, palpable nodularity, or cul-de-sac tenderness. She also had mild suprapubic and bilateral lower-quadrant tenderness to palpation, with voluntary guarding. Initial work-up included a pelvic ultrasound (US) which revealed 2 solid masses within the posterior pelvis, measuring 4.7×1.8×2.4 cm and 1.2×0.7×1.2 cm, respectively, separate from the ovaries, with smooth external borders and internal vascular flow suggestive of endometriomas, schwannomas, or soft-tissue sarcomas (Figure 1). Follow-up pelvic magnetic resonance imaging (MRI) with and without contrast revealed 2 midline posterior pelvic tissue signal intensities with dimensions of 3.2×1.5×2.3 cm and 1.7×1.4×1.8 cm favoring the diagnosis of endometrioma over sarcoma or lymphadenopathy (Figure 2). She underwent a computed tomography (CT) scan to rule out metastasis, and the CT revealed multiple lobular tissue masses in the posterior pelvis adjacent to the vagina, with the largest being 2.5×3.4 cm in diameter, in addition to 2 smaller adjacent lesions, not definitive for endometriosis, but possible splenosis given her history of splenectomy (Figure 3).

With her symptomatology and imaging suggestive of both endometriosis and splenosis, a combined diagnostic laparoscopy involving general surgery and gynecologic surgery with specialized endometriosis training was planned. A diagnostic laparoscopy with lysis of adhesions was performed, where 2 dark-red, congested masses were identified in the posterior cul-de-sac (Figure 4). The larger mass was 4.5×3×1.5 cm in diameter, and the smaller mass was 1.5×1.5×1 cm in diameter (Figure 5). Both masses were successfully resected en-bloc using a vessel sealing device, removed using an in-bag technique, and sent to pathology for evaluation. No endometriosis was identified. Histology confirmed encapsulated ectopic splenic tissue consistent with splenosis (Figure 6). She had an uncomplicated postoperative course and was discharged on postoperative day 1. She experienced total resolution of her dyspareunia and pelvic pain with no recurrence over a 2-year follow-up period.

Discussion

Endometriosis is a benign condition affecting approximately 4 million women in the United States [24]. Defined as endometrial glands and stroma occurring outside the uterine cavity, these ectopic foci of endometrium cause inflammation and fibrosis that can lead to a range of symptoms most commonly dysmenorrhea, dyspareunia, chronic pain, and infertility. Diagnosis of endometriosis is often challenging. An estimated 6 of 10 endometriosis cases are undiagnosed and with a significant diagnostic delay of 4–11 years [25]. Factors contributing to this delay include vague symptomatology that can overlap with other gynecologic, urologic, and gastrointestinal processes and limited detection of endometriosis on imaging and exam, and laparoscopy is the standard criterion for diagnosis.

In this case, the clinical suspicion for endometriosis based on symptomatology with possible endometriomas on imaging was quite high. A Cochrane meta-analysis found that transvaginal ultrasound approaches the sensitivity and specificity needed to replace surgery for endometrioma detection [26]; therefore, our patient’s ultrasound findings suggestive of endometrioma increased our suspicion. Ultrasound findings of endometriomas and splenosis are very similar and may include round, solid masses with internal vascularization [27]. These characteristics were present in our patient’s imaging although the mass was separate from the ovary. MRIs can aid in identification of splenic tissue with specific contrast agents, including super-paramagnetic iron oxide, which is highly specific for reticuloendothelial cells generally abundant in the spleen, or by using scintigraphy with heat-damaged red blood cells tagged with 99mTc or 99mTc-nanocolloidal serum albumin due to its high sensitivity [28]. However, our patient did not receive a specialized MRI as the index of suspicion was not high enough based on US. Although CT is not the most sensitive test for identifying splenosis, only after our patient underwent this imaging to evaluate for potential malignant metastasis was splenosis suggested based on her history. As US is generally the first diagnostic imaging ordered, given the decreased ability to differentiate endometriosis from splenosis, a high index of suspicion should be maintained when ordering follow-up imaging to improve diagnostic accuracy.

Given the ambiguous presentation and imaging of pelvic splenosis, when endometriosis is suspected, many patients undergo diagnostic laparoscopy. However, accurate identification via visualization is also limited. Endometriosis has a wide range of appearances requiring extensive experience and education to identify. It may appear fibrotic, blue, black, red, or vesicular and can have various degrees of nodularity and associated adhesions [17,18]. Splenosis may appear heterogeneous as well with case reports describing “nodular implants of various sizes spread along peritoneal surfaces and bowel,” to “sessile nodules” [19], “bluish implants with a fibrotic capsule”, and “grape-like purple-colored lesions [widely] distributed” [20,21]. When splenosis presents as small, disseminated blue implants, it can be very difficult to differentiate from endometriosis. Zitzer et al [20] suggested the major difference in appearance may be the lack of adhesions in cases of splenosis.

As splenosis is not a pathologic process, removal is not indicated unless it is symptomatic [22]. Although most cases of pelvic splenosis reported in the literature have characterized symptomatic patients, it is likely some have undergone more invasive procedures, including hysterectomies, bilateral salpingo-oophorectomies, multiple laparoscopies, and conversions to open laparotomies [15–22] either for diagnostic purposes or complete removal of a perceived pathologic process such as cancer or endometriosis. It is possible that directed removal of symptomatic implants or masses can decrease surgical morbidity although more study is needed.

Conclusions

With improved awareness concerning patients with a history of splenic trauma or splenectomy, pelvic splenosis may be better identified in patients with symptomatology or imaging findings suggestive of endometriosis. This could lead to more appropriate, directed management.