A unique case of bilateral ovarian splenosis and review of the literature

Splenosis is an acquired anomaly related to heterotopic auto-transplantation of splenic tissue following abdominal trauma or splenectomy. We report the first definitive bilateral ovarian case in a 65-year-old woman who underwent splenectomy following a motor vehicle accident 44 years prior to presentation. We review the literature and discuss the main differential diagnoses. Gross examination revealed a 1-cm well-circumscribed dark nodule on the surface of each ovary. Paraffin-embedded, formalin-fixed blocks were sectioned and stained with hematoxylin-eosin and immunostains (CK5/6, Calretinin, WT1, Vimentin). The histological presence of both red and white splenic pulp, delimitation from ovarian tissue and ovarian origin of blood supply, as well as medical history, led us to the correct diagnosis. The outer nodular surface was covered by mesothelium (WT1+, CK5/6+, Calretinin+, Vimentin+), which was in continuity with the ovarian surface epithelium. To our knowledge, only six previous cases of ovarian splenosis are reported. Our patient is the oldest, with a very long interval from splenectomy to presentation. Clinically, splenosis may mimic malignancy, and a correct diagnosis avoids unnecessary overtreatment. The differential diagnosis includes an accessory spleen, spleno-gonadal fusion, and splenic hamartoma: they should be excluded to come to the correct diagnosis.