Clinical history: A 33-year old male presented with left upper quadrant pain. Imaging demonstrated a 4 cm mass in the inferior pole of the spleen. His past medical history was not significant. A partial splenectomy was performed.
What is your diagnosis?
Discussion and answers
DIAGNOSIS - INFLAMMATORY PSEUDOTUMOUR OF THE SPLEEN
On gross examination, the partial splenectomy weighed 105g and measured 11.0 x 6.1 x 3.2 cm. There was a solitary white firm lesion with lobulated borders measuring 4.4 x 4.1 x 3.2 cm.
Microscopically, the well delimited lesion is composed of fibrous tissue consisting of benign appearing spindle-shaped cells, some stellate in appearance, with interspersed arterioles. Interspersed amongst the spindle-shaped cells are entrapped red blood cells, plasma cells, lymphocytes and histiocytes. Mitotic figures and necrosis are not seen. The uninvolved spleen appears unremarkable.
Inflammatory pseudotumour is a rare reactive lesion consisting of mesenchymal repair and non-specific inflammation. Although it has been described to occur in the respiratory tract, gastrointestinal tract and liver, its location in the spleen is a rare occurrence. The aetiology is not known but infection, vascular and autoimmune causes have been postulated. The lesion is usually considered benign, but close follow-up is recommended. It is not related to the similarly named inflammatory pseudotumour of soft tissue.
The differential diagnosis of a splenic lesion may also include hemangioma,
lymphangioma, hamartoma, hemangiosarcoma, malignant lymphoma and metastatic
carcinoma. Histological examination is required to exclude these neoplasms.
(Yan J et al. Inflammatory pseudotumour of the spleen: report of 2 cases and literature review. Can J Surg. 2008;51:75-76.)