Wandering spleen: A mobile target for radiotherapy
Authors: Kate Gardner, Simon Weston Smith
Journal: American Journal of Hematology (2013)

A 65-year-old female was diagnosed with chronic lymphocytic leukemia in 1997. A bone marrow aspirate showed 95% of nucleated cells were lymphocytes, and on immunophenotyping, the CLL score was 5/5. Cytogenetics were normal. She was treated intermittently as her white cell count (WCC) rose; first with 11 courses of chlorambucil from 2003 to 2006, later with six courses of rituximab, cyclophosphamide, vincristine, and prednisolone (R-CVP) from 2006 to 2007. New splenomegaly was noted in June 2009, which progressed through treatment with three courses of fludarabine, a further three courses of R-CVP (2011), and two cycles of bendamustine-rituximab (2011). She was then referred for splenic radiotherapy, receiving 10.5 Gy in 11 fractions in December 2011. CT monitoring of lung nodules throughout this period has afforded us ample radiology to witness the normally located, albeit enlarged, spleen prior to radiotherapy (see Fig. 1a–c). In March 2012, aged 80, and following splenic radiotherapy, the patient presented with a new lower abdominal mass that was smooth and nontender. An ovarian malignancy was suspected but a CT abdomen confirmed this to be a rotated, prolapsed, and more enlarged spleen (see Fig. 1d–f). The patient's frail state precluded any further interventions. “Wandering spleen” is a rare condition, first described by Van Horne in 1667 during autopsy 1, in which the spleen is not fixed in the left upper quadrant. Case reports in the literature generally focus on complications of a wandering spleen requiring surgery (especially splenic torsion but also splenic haemorrhage). Traditionally, splenectomy was performed but splenoplexy (surgical fixation of the spleen) is now increasingly used, where possible, to preserve splenic function and prevent overwhelming post-splenectomy sepsis. Congenital ectopic spleens are considered to be due to absence of splenic ligaments caused by an embryonic failure of dorsal mesogastrium development 2. The precise etiology of an acquired wandering spleen is unclear, but they have always been documented in association with a lengthened vascular pedicle, with laxity of the splenic ligaments 3. Most, but not all, pelvic spleens are enlarged, but it remains disputed whether this is a cause or a consequence of its malposition. Many have argued that the weight of an enlarged organ gives laxity to the supporting ligaments resulting in a spleen to gravitate downward 4, 5, while others have argued that a torted splenic vein in an ectopic spleen causes splenic congestion and thus splenomegaly. Interestingly, the incidence of a wandering spleen was not seen to be higher in Uganda, a country with endemic splenomegaly secondary to malaria 5. A strong association of wandering spleens with multiparous women has suggested that the direct effect of oestrogen on the abdominal wall during pregnancy may also have a role 4. Noninfective pathologic involvement of a wandering spleen has been described very rarely, but the documented cases have always identified the underlying disease process as a lymphoproliferative disorder. This is the first case to present the wandering of a spleen peri-radiotherapy. Crucially, this case alerts oncologists that radiotherapy targets can be mobile and, for splenic radiotherapy in particular, radiotherapy planning needs to take this into account.