Pelvic splenosis mimicking a suspicious adnexal mass

Abstract

A 58-year-old asymptomatic woman was referred to our gynecologic oncology unit for the management of a left adnexal mass found during a routine gynecologic examination. Her personal history included an emergency splenectomy at the age of 4 years old, following traumatic splenic laceration after a car accident. The patient’s work-up (including transvaginal ultrasound and MRI) confirmed a pelvic solid mass, which was reported as suspicious for malignancy and classified as Ovarian-Adnexal Reporting & Data System-MRI 5. An exploratory laparoscopy was performed, showing a reddish blue lesion located at the left broad ligament. Histologic analysis showed the presence of splenic tissue and normal adnexa. The postoperative follow-up was uneventful.

Pelvic splenosis is a challenging diagnosis rarely made preoperatively due to concern for malignancy. In the presence of a pelvic mass, the collection of a detailed patient’s history, including information about previous splenic rupture, might raise suspicion for pelvic splenosis.

Background

The occurrence of a pelvic mass in a postmenopausal woman often represents a diagnostic challenge for the physician who has to exclude malignancy. Pelvic splenosis is a rare condition, which may occur after splenic trauma-induced splenectomy.¹ Splenosis is mostly found incidentally and reported as a symptom-free condition: its diagnosis is challenging because lesions can be mistaken for a tumour.^2–4 Only few cases of ovarian splenosis or tumor-like lesions of the pelvic wall were reported in the literature.² In such situations, the concern for malignancy may lead to unnecessary surgical diagnostics and treatments, as no therapy is required if the patient is asymptomatic. It is essential to collect a detailed patient’s medical history, including information about previous splenic rupture or splenectomy, when considering this diagnosis. However, a surgical approach cannot always be avoided in presence of a solid pelvic mass. Here, we report a case of ovarian splenosis mimicking a suspicious adnexal mass, leading to invasive diagnostic and surgical procedures.

Case presentation

A 58-year-old, asymptomatic, postmenopausal woman was referred to our gynecologic oncology unit for the management of a suspicious left adnexal pelvic mass discovered during a routine gynecologic and transvaginal ultrasound examination. Her personal history included two spontaneous deliveries 13 and 14 years earlier and an emergency splenectomy performed following a car accident when she was 4 years old. She had no family history for ovarian cancer.

Investigations

The patient’s workup included a transvaginal ultrasound. It showed a smooth solid lesion classified as Ovarian-Adnexal Reporting & Data System-Ultrasound 5 with a vascularisation score of 4 and ≥50% risk of malignancy according to the international ovarian tumour analysis (IOTA). MRI confirmed a 4.4 cm solid lesion on the left adnexa contiguous to the left ovary, showing an intermediate–high signal on T2-weighted images and restricted diffusion with very low apparent diffusion coefficient (ADC) values (mean ADC 0.5×10⁻⁶ mm²/s). The lesion presented a type 3 enhancement curve on dynamic contrast enhancement (DCE). It was, thus, classified as Ovarian-Adnexal Reporting & Data System (ORADS)-MRI five and reported as malignant. (figure 1) Serum CA125 level was low (25kU/l).⁵ As the concern for malignancy was high, an exploratory laparoscopy was proposed. Entering the abdomen, we directly saw reddish-blue lesions. The largest tumor-like lesion was attached to the left broad ligament, though ovary and fallopian tube were normal. The second lesion was located in the omentum, while the third and fourth nodules were attached to the serous membranes of the small bowel. They appeared encapsulated and well vascularised. Intraoperatively, frozen section examination of the adnexal nodule revealed adipose and lymphoid tissue without tumour cells. Consulting expert visceral surgeons advised leaving the second lesion attached to the digestive wall and waiting for final pathology results. (figure 2)

Figure 1.

Pelvic MRI showing a 4.4 cm solid left adnexal lesion with intermediate-high signal intensity on axial T2 weighted images white arrow on (A) attached to the lateral side of the left ovary white arrowhead on (A). The lesion presents restricted diffusion(B) and a type 3 enhancement curve on DCE (C and D). DCE, dynamic contrast enhancement.

Figure 2.

Laparoscopic image showing the left adnexal mass, two well-vascularised lesions attached to the serous membranes of the small bowel, corresponding to gastrointestinal splenosis.

Outcome and follow-up

Postoperative histologic analysis of the subsequent bilateral adnexectomy and partial omentectomy showed the presence of splenic tissue being composed of red and white pulp described as splenosis. The post-operative follow-up was free of complications and the patient remained asymptomatic(figure 3).

Figure 3.

Histologic illustration of the left adnexal mass showing splenic tissue with red and white pulp.

Discussion

Splenosis is an uncommon condition described as auto-transplantation of splenic functional tissue to abnormal locations. It was reported to be found in up to 76% of patients following trauma-induced splenectomy.^{1 4 6} Splenosis results from migration of splenic cells to abdominal-pelvic or thoracic host tissues, as a result of splenic rupture.^{2 7} Some rare cases of cerebral splenosis were reported, explained by a mechanism of intravascular dissemination of splenic cells.⁸ Nodules can vary in shape, number (1 to >100), and size (ranging from few mm to >10 cm).² Their growth is limited by local vascularisation.^{2 9}

Splenosis is an acquired condition which should not be confused with an accessory spleen, a congenital condition occurring when fusion of primordial splenic buds fails. Accessory splenic nodules are usually located close to the spleen and are vascularised by the splenic hilum. Similar to splenosis, accessory spleen is described as functional splenic tissue consisting of both white and red pulp.⁷

The adnexal region is an unusual location for splenosis, which is a condition generally unfamiliar to clinicians. Frequently, these pelvic adnexal masses are identified incidentally in asymptomatic patients during investigation for other pathologies. Less frequently, symptoms may occur, either due to compression of other organs or bleeding, resulting in pelvic pain or signs of infection.^{2 7}

No treatment is recommended for asymptomatic cases. Imaging techniques to investigate these adnexal masses (transvaginal ultrasound, CT or MRI) can be misleading, as they may be unable to differentiate a neoplasia from a benign mass.^9–11 At ultrasound, splenosis often corresponds to smooth solid lesions with high vascularisation, which can falsely result in a high probability of malignancy based on IOTA classification and ORADS-ultrasound scores up to 5. According to the ORADS-MRI classification, an ovarian splenosis can be misclassified as it presents with restricted diffusion and intense enhancement on DCE with a type 3 curve.¹² At this point, clinicians concerned about potential malignancy may then recommend invasive management such as surgical procedures. Indeed, most cases of ovarian splenosis described in the literature were diagnosed after surgery.⁷ Heat-damaged Tc-99m red cells scintigraphy is the reference standard imagine technique for diagnosis of splenosis: this dedicated examination may confirm the presence of splenic tissue and potentially avoid invasive procedures in a patient with a history of traumatic splenic.¹³ However, heat-damaged Tc-99m red cell scintigraphy is not widely available and an alternative option using 99mTc sulphur colloid scan or 99mTc phytate scan may also be considered. If the diagnosis of splenosis is confirmed with these techniques, a surgical treatment could be avoided.^{12 14}

Recognition of this unusual condition may also depend on its size or localisation, and a surgical approach cannot always be avoided. Splenic implants should not be removed unless resulting in symptoms such as organ compression or bleeding. As described in our case, small lesions attached to gastrointestinal wall should be left in place as they rarely lead to symptoms.⁷ These neoformed splenic nodules ensure a haematological and immunological function similar to the spleen. Therefore, preservation of splenic tissue can help to reduce the severity of bacterial infection.^{15 16}

Conclusion

Pelvic splenosis is a benign and rare condition requiring no therapy. This can be particularly challenging as splenic nodules can mimic neoplasia on conventional imaging including transvaginal ultrasound, CT and MRI. Thereby diagnosis is rarely made preoperatively and the concern for malignancy frequently leads to surgery. A patient with a medical history of traumatic splenic laceration who presents with an asymptomatic mass should undergo dedicated nuclear medicine examinations to confirm the diagnosis of splenosis in order to avoid an invasive surgical procedure.

Learning points.

• Pelvic splenosis is a rare benign condition and does not require treatment.

• Pelvic splenosis may have imaging characteristics that mimic suspicious ovarian neoplasia, endometrioma or metastatic cancer.

• Clinicians should consider splenosis as a differential diagnosis in asymptomatic patients with a history of splenic rupture.

Ethics statements

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