Infectious mononucleosis presenting as spontaneous splenic rupture without other symptoms

Military Medicine, Sep 2003 by Stockinger, Zsolt T

Splenic rupture is an uncommon complication of infectious mononucleosis (IM), occurring in 0.1% to 0.5% of all patients. It remains the most common lethal complication of IM. Rupture of the spleen with no other symptoms of IM is almost unheard of. This is the report of a case of spontaneous splenic rupture requiring splenectomy in a patient with a positive heterophil antibody test and no other signs or symptoms of IM. The diagnosis and management of splenic rupture in IM are discussed.

Introduction

Infectious mononucleosis (IM) is caused by the Epstein-Barr virus and is common in young adults, peaking between 18 and 23 in males and 15 to 16 in females with an incidence of 345 to 671 cases per 100,000 population per year.1 As such, it is well known in the military population. After an incubation of 4 to 7 weeks after infection, it most commonly manifests with the classic triad of fever (occurring in 89% of patients), pharyngitis (78%), and cervical adenopathy (94%), although splenomegaly (49%), hepatomegaly (6%), jaundice (4%), and rash (7%) may also be present.1 Symptoms are usually self-limited. However, only 25% to 70% of young adults with acute Epstein-Barr virus infection develop the clinical syndrome of IM.2

Diagnosis is usually confirmed by a positive heterophil (Monospot) antibody titer, although this has a 10% to 20% false negative rate. Tests that directly measure Epstein-Barr virus antibodies are typically reserved for cases of suspected IM that do not produce heterophil antibody.1 Other laboratory abnormalities usually include leukocytosis (although leucopenia can occur early in infection) with a predominance of atypical lymphocytes (usually approximately 30%) and monocytes and mild thrombocytopenia in 50% of patients.1 Mild elevations in liver function tests are also common in 90%.2

Splenomegaly is common, clinically appreciable but asymptomatic in approximately one-half of all patients2-4 but radiographically apparent in almost 100%.2 Splenic rupture is a well-documented but uncommon complication of IM, occurring in 0.1% to 0.5% of patients,1,2 and it is the most common fatal complication.5 In one large review of 107 cases of splenic rupture in IM, only 18 were felt to be spontaneous by strict criteria including no recent trauma.4 In a recent review, only three confirmed and two possible cases of splenic rupture in otherwise asymptomatic patients were found in the world literature.6 This report would constitute an additional case.

Case Report

A 21-year-old Caucasian male Marine presented to his unit's Battalion Aid Station with a 1-day history of vague abdominal pain and nausea. He denied fever, sore throat, dysphagia, respiratory symptoms, or other complaints, and his physical examination was reported to be unremarkable. He adamantly denied trauma, either within or outside of his normal duties and training. The next day he returned to the Battalion Aid Station after sudden onset of severe left upper quadrant abdominal pain, radiating to his left shoulder. On examination, he was felt to have peritoneal signs and was transported by ambulance to the nearest U.S. military hospital.

In the Emergency Department, the patient was afebrile, normotensive, and mildly tachycardic. Physical examination found no cervical or other lymphadenopathy. No rash or scleral icterus was noted. Palpation of the abdomen revealed diffuse abdominal pain with involuntary guarding. The patient again denied trauma, fever, sore throat, or any respiratory symptoms during the preceding several weeks. A complete blood count showed: hemoglobin, 8.4 g/dl; hematocrit, 26.1%; platelet count, 126,000/[mu]l; white blood cell count, 2,600/[mu]l with 40 neutrophils, 6 bands, 48 lymphocytes, 3 monocytes, 2 atypical lymphocytes. Computed tomography revealed marked splenomegaly with splenic rupture (Fig. 1, large arrow) and free intraperitoneal blood (Fig. 1, small arrows). At this point, general surgery was consulted.

At operation, a 2,800-cc hemoperitoneum was evacuated. The spleen was found to be massively enlarged with a 10-cm rupture (Fig. 2). Splenectomy was performed, and 4 units of packed red blood cells were transfused intraoperatively. Postoperatively, the patient did well and required no further transfusion with a discharge hemoglobin of 9.6. Platelet count rose to over 1 million and daily aspirin was begun, which was discontinued at his first postoperative clinic visit when the platelet count had returned to normal. He was vaccinated for meningococcus, pneumococcus, and Haemophilus influenzae prior to discharge.

The excised spleen was grossly enlarged, weighing 760 g (normal, 75-100 g)3 and measuring 16.0 x 12.0 x 7.2 cm. Histology revealed prominent expansion of the red pulp by dilated and congested sinuses with immunoblastic and plasma cell infiltration of the cords and trabeculae. These findings were consistent with IM.2 Heterophil (Monospot) antibody test drawn on the day of surgery was positive.

Discussion

Splenomegaly in IM is common, but splenic rupture is reportedly rare. In their report of subcapsular splenic hematoma in IM, Patel et al.7 suggest that splenic rupture is probably always preceded by subcapsular hematoma. Therefore, contained rupture (i.e., subcapsular hematoma) would precede free rupture into the peritoneum, and as such the true incidence of "splenic rupture" would be underreported.