Spontaneously Ruptured Spleen Samples in Patients With Infectious Mononucleosis

Analysis of Histology and Lymphoid Subpopulations

Marcos M Siliézar, MD; Catuxa Celerio Muñoz, MD; Jon Danel Solano-Iturri, MD; Laura Ortega-Comunian, MD; Manuela Mollejo, MD; Santiago Montes-Moreno, MD; Miguel A Piris, MD

Disclosures

Am J Clin Pathol. 2018;150(4):310-317. 

In This Article

Discussion

Spontaneous rupture of the spleen is a well-established complication of IM. Nevertheless, descriptions of spleen histology are scarce, and few individual cases have been described, to our knowledge.

Although some of the patients with this complication may have been previously diagnosed with IM, cases may arrive at a pathology department without appropriate clinical information and receive an incorrect diagnosis. Indeed, most of the cases described here were initially considered possible lymphoma cases, and their tissue samples were sent abroad for a second opinion.

During the same period, we have had the opportunity to review approximately 700 cases of spleen specimens involving different lymphoproliferative processes, derived from our own files and consultation cases from many Spanish hospitals. Therefore, spleen specimens in patients with IM represent roughly 1% of the examined splenectomy specimens.

As Table 2 shows, most of the cases are from pediatric patients (four of six), so we might expect the frequency of splenectomy specimens involving IM to be higher in pediatric hospitals or pathology departments receiving mainly specimens from pediatric patients.

All the cases considered here yielded similar findings, with red pulp expansion, which appears to be occupied by activated T and B cells, together with a polymorphic background including macrophages, small lymphocytes, and plasma cells. EBV-positive cells were a minor component in all cases, comprising fewer than 20% of cells in the spleen; most of the infiltrate was therefore made up of a complex inflammatory background rich in cytotoxic T cells and macrophages. Significantly, both B- and T-cell activated large cells were identified, a finding that, in our experience, often supports the suspicion of IM.

The mechanism of splenic rupture in IM is unclear but may be related to the sudden development of splenomegaly, since the spleen is much smaller than in other low-grade lymphomas involving the spleen. Destruction of support elements, such as vessels or the connective trabeculae, could also play a role.

Spontaneous rupture of the spleen can also occur in large B-cell lymphoma splenic infiltration, a diagnosis that we excluded because of the polymorphic background, EBV presence, and lack of immunoglobulin gene monoclonal rearrangements. Differential was also performed with splenic involvement by angioimmunoblastic T-cell lymphoma, in which EBV-positive scattered B cells can also be observed, although we are not aware of cases of splenic spontaneous rupture in this condition.

IM should be considered a possible diagnosis in any case of splenic rupture whose histology may suggest aggressive lymphoma Table 4.

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