Prepared by Manzoor Ahmed, MD and Thomas Poulton, MD of the Department of Radiology, Aultman Hospital, Canton, OH.

CASE SUMMARY

A 15-year-old white girl presented to the emergency room with acute mid-abdominal pain, nausea, and vomiting. Her medical history was remarkable only for autoimmune hepatitis. On physical examination, a tender palpable mass was present in the lower abdomen and pelvis. Contrast-enhanced computed tomography (CT) (figure 1) and abdominal ultrasound (US) (figure 2) were performed.

DIAGNOSIS

Wandering spleen with torsion

IMAGING FINDINGS

Contrast-enhanced CT of the abdomen and pelvis demonstrated the absence of the spleen in the left upper quadrant, with the normal spleen bed replaced by bowel gas (figure 1A). An enlarged spleen is located abnormally in the lower abdomen and upper pelvis, and it showed a lack of enhancement with a "whorled" appearance of its pedicle (figures 1B and C) consistent with torsion. Abdominal US was performed to confirm torsion as shown by the absence of Doppler flow to the spleen (figure 2). Splenectomy was performed. Surgical and pathologic findings confirmed wandering spleen with torsion.

DISCUSSION

Wandering spleen means an abnormally located spleen with a long pedicle. ¹ It is a rare cause of acute abdomen, ² and is usually quiescent unless transient or persistent torsion of its pedicle occurs. Timely preoperative diagnosis is required to avoid potential complications such as hemorrhagic infarction, splenic gangrene, formation of a cyst or abscess, and development of pancreatic tail necrosis. ^3-5 In their review of 1413 cases of splenectomies, Erkalis and Filler ⁶ found only 4 reported cases of wandering spleen. Similarly, Broker et al ⁷ documented 3 cases during a 24-year period, while Allen and Andrew ⁸ reprted 35 cases of wandering spleen in children, most of whom presented as acute emergencies.

While the reported age incidence of wandering spleen ranges from 3 months to 98 years, ^5,9 it is found typically in children under 10 years of age. This condition has no gender predominance, ⁹ and is common in patients of African descent. ⁵ Asymptomatic patients may present with splenomegaly or abdominal mass. Symptomatic patients present with either intermittent mild abdominal pain (due to torsion and spontaneous detorsion) or frank acute abdomen from torsion of the splenic pedicle and impending infarction. ^1,4,9

In children, the typical etiology is abnormal development of dorsal mesogastrium; in adults, possible causes include laxity of ligaments, splenomegaly, and trauma. ^2,9 The spleen and its main supporting structures, the lienorenal and gastrolienal ligaments, arise in the dorsal mesogastrium. These ligaments stabilize the spleen, but do allow some mobility. The lienorenal ligament is formed by fusion of the posterior leaf of dorsal mesogastrium with parietal peritoneum. In the process, the pancreas acquires its retroperitoneal location. Incomplete fusion results in a long pedicle, which may include the distal tail of the pancreas. ^9-11 The splenocolic, splenophrenic, and phrenicolic ligaments are other supporting structures. The phrenicolic ligament forms a resting slip for the spleen. ¹¹

Ultrasound is usually one of the first studies performed for evaluation of an abdominal mass. On sonography, the wandering spleen with torsion appears enlarged and may show subcapsular hemorrhage. ³ Doppler flow is absent in complete torsion, as was evident in this case. Plain films may show nonspecific findings, such as the absence of a splenic shadow in left upper quadrant replaced by bowel gas, and mass effect in the lower abdomen or pelvis. ¹¹ CT manifestations have been well described, including the absence of the spleen in its normal location, lower abdominal or pelvic mass, whorled appearance of the splenic pedicle, ascites, pancreatic tail necrosis, and pseudocapsule (in chronic torsion). ^9-11 Scintigraphy with Tc99m sulfur colloid can show the abnormal location and function of the spleen (ie, diminished function or no uptake), but nonvisualization of the spleen is a nonspecific finding that can also be seen in functional asplenia. ¹ Angiography is an option for the definitive diagnosis of torsion or may be obtained pre-operatively to define vascular detail. ^1,12

Splenectomy is the treatment for acute torsion. Splenopexy is an option for a noninfarcted spleen. ³ The pancreatic tail should be inspected for necrosis at the time of surgery. ¹²