Susumu Umemoto MD, Department of Urology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura Kanazawa-ku, Yokohama 236-0004, Japan. Email: firstname.lastname@example.org
Abstract: Heterotropic splenic tissue in renal fossa is characteristically asymptomatic and is usually an incidental finding that has been reported to mimic renal or adrenal tumors. A 55-year-old man with renal cell carcinoma had undergone radical nephrectomy together with splenectomy because of disrupture of the splenic capsule. During a follow-up examination, three nodules were detected by computed tomography scan in the splenorenal area and they slowly enlarged. Although local recurrence was highly suspected, we decided to rule out splenosis. We successfully diagnosed these masses as ectopic splenic tissues by a technetium sulfur colloid scan and unnecessary surgical exploration was avoided.
Splenosis is defined as autotransplantation of splenic tissue after splenectomy for trauma or surgical reasons. It can occur inside or outside the peritoneal cavity and is enlarged in either location. Splenic implants in the thorax or abdomen might be misdiagnosed as malignant neoplasms. A technetium (Tc)-99 m sulfur colloid is sequestered by reticuloendothelial cells and can be used to diagnose splenosis containing reticuloendothelial cells.
We report a case of splenosis that was highly suspicious for local recurrence of renal cell carcinoma (RCC) after concurrent left-sided nephrectomy and splenectomy. We made a successful differential diagnosis using a Tc-99 m sulfur colloid scan and were able to avoid unnecessary intervention.
A 55-year-old man was referred to our hospital for suspected recurrence of RCC. His medical history was a left-sided radical nephrectomy for RCC via a transperitoneal approach and splenectomy because of rupture of the splenic capsule during removal of a kidney at another hospital 4 years earlier. Histopathologic examination showed pT3aN0M0, V(+), grade 2 >> 1, clear cell RCC. Postoperative adjuvant interferon-alpha was given for approximately 1 year.
At 1 year after surgery, a computed tomography (CT) scan of the abdomen showed three homogeneous well-defined and nodular masses with maximum diameters of 3 cm in the splenorenal area (Fig. 1). None of the lesions were visible in the previous follow-up or preoperative CT scans. Follow-up intermittent CT scans showed that the tumor lesions very slowly increased in size, up to almost 5 cm in maximum diameter after 3 years. Because local recurrences of RCC were strongly suspected, interleukin-2 was given for 2 months, but there was no response. Subsequently, he was referred to our hospital for possible surgical resection of the tumor lesions. All laboratory investigations were within their normal ranges. A CT scan of the chest and a bone scan were negative for metastasis. Positron emission tomography imaging showed no aberrant accumulation.
Because the patient had undergone nephrectomy concurrently with splenectomy, the tumors were located near the pancreatic tail and the main tumor was an unusual shape (pearl-tear or ‘Magatama’-like shape) for RCC recurrence, we decided it was necessary to rule out splenosis. Radionuclide liver/spleen scintigraphy with Tc-99 m sulfur colloid showed hotspots in the areas consistent with the masses observed on the abdominal CT (Fig. 2). Therefore, we concluded that these masses contained cells of reticuloendothelial origin that differed from local recurrence of RCC, and avoided unnecessary surgical exploration. A follow-up CT examination after 1 year showed that the masses remained unchanged in terms of size and shape.
Ectopic splenic tissue can be acquired or congenital. The cause of accessory spleen is congenital. Splenosis refers to ectopic autotransplanted splenic tissue after trauma and/or removal of the spleen.1 Splenic implants can be located anywhere accessible to the fragmented splenic tissue, including the peritoneal cavity, pelvis, retroperitoneum, mediastinum, pleural cavity and subcutaneous tissue.2 The most common sites of implantation are the serosal surface of the small intestine, greater omentum, parietal peritoneum, surface of the large bowel, mesentery and surface of the diaphragm.3 Splenosis usually varies in shape, has no hilum and is a sessile growth.4 Splenosis has been reported to occur in 26–67% of patients after trauma associated with splenic rupture or therapeutic splenectomy.5
Because splenosis is generally asymptomatic and seldom recognized clinically, splenic implants are usually discovered during surgical exploration, unrelated diagnostic imaging or at autopsy.
Splenic implants in the abdomen might be misdiagnosed as presumed malignant masses, such as renal, adrenal, pancreatic and retroperitoneal tumors.6 Ultrasound examination and CT scans lack specificity for correctly diagnosing splenosis and frequently lead to false diagnosis of tumors. Therefore, unnecessary surgical procedures, such as nephrectomy and aderenalectomy, have been reported.7
The presence of a solid mass in the renal fossa after nephrectomy for RCC is generally suspected to be local tumor recurrence. A case report of misdiagnosis of splenosis or splenic tissue for local recurrence of RCC after radical nephrectomy has been documented.8 In our case, we also strongly suspected tumor recurrence initially. However, CT imaging showed that the main tumor had a pearl-tear or ‘Magatama’-like shape and this seemed unusual for typical RCC recurrence. In addition, the tumor growth was very slow. A history of previous splenectomy also alerted us to the fact that these masses might represent splenosis.
Fine-needle biopsy is still controversial and of limited value in the assessment of renal masses. The major problem with this technique is the high incidence of false-negative biopsies in patients with renal malignancy. Neuzillet et al.9 and Lechevallier et al.10 reported that the biopsy material was insufficient for pathologic analysis in 3.4% and 21% of their cases, respectively. Although the incidence of complications has significantly reduced since the introduction of smaller-gauge needles, the potential complications of biopsy include bleeding, infection, arteriovenous fistula, needle-tract seeding and pneumothorax. In our case, the tumor lesion was relatively small, and furthermore, the anatomical alignments of the intra-abdominal organs, tissues and vessels were changed after surgery. Under these circumstances, we did not consider that biopsy would be useful for a differential diagnosis.
A non-operative diagnosis of splenosis can be achieved with a Tc-99 m sulfur colloid scan,11 Tc-99 m heat-damaged red blood cell scan12 or ferumoxide-enhanced magnetic resonance imaging.13 These methods efficiently detect heterotopic spleen with high specificity and sensitivity. The Tc-99 m sulfur colloid is sequestered by reticuloendothelial cells and can be used to correctly identify the presence of splenic tissue within masses. This method is the most commonly used examination, because it is easy to carry out. Therefore, we adopted this examination for our patient. However, although a Tc-99 m heat-damaged red blood cell scan is more complicated, it only views splenic tissue and can detect small pieces of splenic tissue. Therefore, this type of scan can assess the usefulness of cases in whom the splenic tissue is located in direct apposition to the hepatic tissue. Ferumoxides (Feridex, Advanced Magnetics, Cambridge, USA) are magnetic resonance contrast agents composed of superparamagnetic iron oxide particles that are preferentially taken up by reticuloendothelial cells of the liver and spleen. Ferumoxides produce local inhomogeneities in the magnetic field that cause rapid dephasing of transverse magnetization, resulting in a loss of signal intensity on T2-weighted magnetic resonance images. At present, there are few reports showing the usefulness of magnetic resonance imaging with ferumoxides for the detection of splenosis. However, the accuracy of this imaging technique for identifying splenosis is reported to be high, indicating that it will be commonly used in the near future.
In conclusion, we report here a case for diagnosing splenosis mimicking local recurrence of RCC with Tc-99 m sulfur colloid scan, thus avoiding unnecessary surgical intervention. Any mass appearing in the splenic-renal-pancreatic region after nephrectomy with splenectomy requires complementary investigations to avoid a false diagnosis of renal tumor recurrence. Moreover, our observations indicate that clinicians should be aware that masses inside or outside the peritoneal cavity with a history of previous splenic trauma or splenectomy might represent splenosis.