CASE REPORT 
Annals of Nuclear Medicine Vol. 9, No. 3, 145-147, 1995 

The value of combined 99mTc-Sn-colloid and 99mTc-RBC scintigraphy in the evaluation of a wandering spleen 
 
Masashi SHIMIZU, Hikaru SETO, Masanari KAGEYAMA, Yi-wei Wu, Toshirou NAGAYOSHI, Yuichi KAMISAKI, Makoto MORIJIRI, Naoto WATANABE and Masao KAKISHITA 

Department of Radiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University 

Wandering spleen is the term commonly applied to splenic hypermobility that results from laxity or maldevelopment of its suspensory ligaments. It comes to medical attention usually as an abdominal mass, or when the spleen undergoes torsion. Diagnosis on clinical grounds alone is rarely made, and ultrasonography, CT and MRI findings have no specific characteristics for this condition . 99~Tc-labeled colloid taken up by the spleen may provide a specific diagnosis. We report a case of wandering spleen, in which the preoperative diagnosis was made on the basis of sequential liverspleen scintigraphy with 99~Tc-Sn-colloid and blood-pool scintigraphy with 99*Tc-RBC. This is a rare case, in which hypermobility was assessed by sequential 99mTc-Sn-colloid scintigraphy, and to our knowledge, is the first case in which 99mTc-RBC scintigraphy provided useful information on splenic blood volume and its location. 

Key words: wandering spleen, 99mTc-Sn-colloid, liver-spleen scintigraphy, blood-pool scintigraphy, 99mTc-RBC 

INTRODUCTION 

WANDERING SPLEEN is an uncommon condition in which the spleen is located lower than in the left upper quadrant1 and is most often brought to the physician's attention when the spleen simulates a mass or undergoes torsion. 1,2 It is characterized by laxity or absence of supporting splenic ligaments, with splenomegaly also originally considered to be the major predisposing factor. 1-4 Diagnosis on clinical grounds alone is rarely made, and findings of ultrasonography, CT and MRI suggest no specific diagnosis.3,4,6 99mTc-labeled colloid taken up by the spleen may demonstrate specific characteristics for this condition.4,7 We report a case of wandering spleen, in which sequential 99mTc-Sn-colloid scintigraphy was of great clinical value in the evaluation of spleen mobility and size change, and moreover, 99mTc-RBC scintigraphy provided useful information on the vascularity and blood volume of the spleen.

CASE REPORT 

A 35-year-old woman received medication at a local hospital for membrano-proliferative glomerulonephritis. Marked splenomegaly was incidentally found by ultrasonography and liver-spleen scintigraphy with 99mTcSn-colloid (Fig. 1) Sep. 1990. She had subsequently undergone a follow-up study for kidneys and spleen by ultrasonography. She had previously noticed splenic mobility, but recently she became aware of a large mass in the pelvis located at a site lower than noticed before. She was then admitted for further examination of the giant pelvic mass in July, 1994. On physical examination, a hard, tender pelvic mass was found. Pancytopenia was seen due to hypersplenism (RBC 372 x 104, WBC 3700, Platelet 8.4 x 104 per mm3). The other laboratory data were within normal limits. Ultrasonography, CT and MRI findings showed a large, solid mass in the pelvis. Angiography, performed for preoperative planning, showed dilatation of the splenic artery supplying blood to a giant spleen in the pelvic region (Fig. 2). The second liver-spleen scintigraphy was performed ten minutes after intravenous injection of 185 MBq of 99mTc-Sn-colloid. The spleen was more enlarged and displaced lower than in the previous study (Fig. 3). 99mTc-RBC scintigraphy was performed to estimate the blood volume of the spleen. Radionuclide angiography with 99mTc-RBC (740 MBq) revealed increased arterial flow to the giant pelvic mass. Blood-pool scintigraphy conducted ten minutes later revealed a giant hypervascular mass in the pelvis, but no vascular component in the left upper quadrant. Because the spleen was located in the anterior abdomen, we did volume measurement of the left ventricle on an equilibrium ventriculogram and calculated the blood volume of the giant spleen with the following equation: Spleen volume 

=(Blood-sample volume) x (Spleen count rate) /(Blood-sample count rate) 

We estimated the blood volume of the spleen to be 690 ml (Fig. 4). Splenectomy was performed to prevent torsion and improve the pancytopenia. At surgery, the spleen weighed 580 g and measured 16.5 x 10.5 x 6.0 cm. Pathological examination revealed chronic congestion of the spleen. After splenectomy the pancytopenia improved (RBC 429 x 104, WBC 6500. Platelet 8.6 x 104 per mm3). 

DISCUSSION 

"Wandering spleen" (also known as "ectoprc spleen," "floating spleen," and "splenic ptosis") is very rare and occurs primarily in women. Agenesis and laxity of the suspensory ligaments of the spleen are the most frequent causes.1 Splenomegaly may enhance the potential for migration and torsion in the presence of an embryologic defect, but splenomegaly alone does not lead to abnormality of the splenic position.4 Many patients with a wandering spleen are symptomatic early in life, and occasionally acute abdominal pain may result from torsion of the splenic pedicle.1 Because of the rarity of this condition and the variety of clinical presentations, diagnosis on clinical grounds alone is difficult. The main clinical finding is usually an abdominal or pelvic mass.9 

Various techniques have been used to evaluate wandering spleen. Ultrasonography, CT and MRI usually demonstrate a solid mass, but may not disclose the nature of the mass.6,9 Definitive preoperative diagnosis is achieved only by angiography,1 but it is a more invasive technique. Since colloid is taken up specifically by the spleen and liver, the nature of the mass may be established by scintigraphy4,7 and 99mTc-damaged RB C scintigraphy may also provide a specific diagnosis. When there is twisting of the vascular pedicle producing congestion and/or infarction, radionuclide labeled colloid uptake by the spleen may be diminished or absent, depending upon the degree of compromise in the splenic vascular supply.2,3,5 Previous reports have revealed that a diagnosis of wandering spleen may be made by scintigraphic visualization of the spleen in positions other than the left upper quadrant, but most reports did not show the movement of the spleen.4,7,lo This report illustrated the movement of the spleen to a lower position and an increase in size compared to the first scan by sequential 99~Tc-Sn-colloid scintigraphy. 

99mTc-RBC scintigraphy in a case of wandering spleen has not been reported to our knowledge. If it reveals an 
intense focal uptake in an abdominal or pelvic mass, and no vascular component in the left upper quadrant, it may be diagnosed as a wandering spleen in shape and in location. Moreover, the blood volume of the spleen may be estimated. In this case, we estimated the blood volume of the spleen to be 690 ml. The estimated volume was found to be relatively accurate when compared with the weight of spleen (580 g) after splenectomy. 

It may be concluded that 99mTc-Sn-colloid scintigraphy is of great clinical value in the evaluation of a wandering spleen, and 99mTc-RBC scintigraphy provides specific diagnosis and useful information regarding the vascularity and blood volume of the spleen for preoperative planning. To our knowledge, this is the first reported case which was assessed by 99mTc-Sn-colloid and 99mTc-RBC sci ntigraphy. 

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