Objectives: Spontaneous rupture of the spleen is occasionally seen as the presenting event in infectious mononucleosis (IM). Diagnosis of these cases can be very challenging.
Methods: We describe the morphologic and immunohistochemical findings in a series of seven splenectomy specimens removed after spontaneous rupture in patients with IM. Most cases were submitted for a second opinion since the histology of the cases suggested malignant lymphoma.
Results: All the cases showed similar findings, with red pulp expansion occupied by activated T and B cells, including scattered large lymphocytes with both T- and B-cell markers, together with a polymorphic background rich in cytotoxic T cells. Clonality analysis revealed T-cell receptor clonal patterns in four of the six cases evaluated.
Conclusions: IM should be considered a possible diagnosis in any case of splenic rupture whose histology suggests possible aggressive lymphoma.