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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.

People who have undergone splenectomy mount a poor IgM response to bacterial polysaccharide vaccines. Whether this defect is true during natural bacterial and viral infections is unknown. We present 2 cases of postsplenectomy cytomegalovirus (CMV)-induced mononucleosis with impaired IgM but normal to augmented IgG response. The cases presented initial diagnostic challenges owing to a prolonged course of infection, marked lymphocytosis (peak lymphocyte count, 27,900/microL [27.9 10(9)/L]), clonal T-cell proliferation with T-cell receptor g gene rearrangements, and remote history of splenectomy. However, the acute nature of the infections, serial determinations of the anti-CMV IgM and IgG, exclusion of other causes, and detection of CMV in the blood established the diagnosis and revealed the deranged antibody response. The infections resolved without specific treatment. These cases suggest that the spleen might be a primary site for specific anti-CMV IgM response.

False positive heterophile test results for infectious mononucleosis are rare but may lead to diagnostic confusion. A patient with Klebsiella hepatic abscess is described in whom a persistently false positive heterophile test resulted in delayed appropriate diagnosis and therapy.

Lymph nodes from patients with acute infectious mononucleosis (AIM) typically show marked paracortical expansion and a prominent immunoblastic proliferation that can occur in nodules and sheets, as well as within sinuses. The marked immunoblastic proliferation, coupled with Reed-Sternberg-like cells and a polymorphous inflammatory cell background, may simulate either non-Hodgkin's lymphoma or Hodgkin's disease. A recently described entity, Ki-1-positive lymphoma, or large cell anaplastic lymphoma, shares some clinicopathologic and phenotypic features with AIM and must be considered in the differential diagnosis. The present case describes a 20-year-old male who had signs and symptoms consistent with AIM, which he was later proven serologically to have, but whose cervical lymph node showed features suspicious for large cell anaplastic lymphoma. In addition, the Ki-1 (CD30) antigen was expressed by some of the atypical immunoblasts, further raising this possibility.

The participant performances on 1977 and 1978 infectious mononucleosis survey specimens are tabulated. The various methods utilized gave similar results on negative specimens. Commercial reagent kits incorporating differential absorption performed somewhat better on positive specimens than kits without differential absorption. Many of the commercial reagent kits performed very poorly on the false postitive specimen.

The present report-describes serologic data from five individuals without infectious mononucleosis (IM) who had very high levels of horse red blood cell agglutinins (1:896-1:7168) that were unusual in that they were minimally absorbed by either guinea pig kidney or beef red blood cell suspensions. Agglutination of sheep red blood cells was negative, and Epstein-Barr virus (EBV)-specific serodiagnostic tests revealed evidence for long past primary infections. In one of the five cases, serologic findings suggested a more than usually active EBV carrier state, as evident from persistently high anti-VCA (IgG) levels of 1:1280 and the continual presence of anti-R at 1:40. Sera from all cases predictably interfered with several commercially available IM-specific rapid slide agglutination tests. The incidence of such findings was estimated to be no more than one per one thousand non-IM cases. In three patients adequately studied, the poorly absorbable horse agglutinins persisted in serum samples over periods of five to nine years. The significance of these findings is discussed.

In many laboratories, rapid slide tests incorporating differential absorption have replaced heterophil antibody tube tests in the investigation of suspect infectious mononucleosis. The present report describes serologic data from five individuals whose Monospot tests remained falsely positive for four years or more without other evidence of infectious mononucleosis or underlying disease states. Three of the five had never been infected with the Epstein-Barr virus. All five had negative results when studied with the ox cell hemolysin and the horse cell differential absorption tube tests. False-positive test results have also been encountered in healthy controls, as frequently as in patients with underlying disease states. The authors are unable to attach any clinical significance to the findings of an isolated falsely positive Monospot test even when it persists for many months or years.

An evaluation of the Mono-Chek test shows it to be easy to read, fast and simple. In accuracy it compares favorably with the Paul-Bunnell (P-B) test and the Davidsohn modification of the Paul-Bunnell (P-B-D) test and is equal to the Mono-Spot test.

A case of rapidly fatal histiocytic medullary reticulosis in which two positive mono-spot tests were found is presented. In addition, there was a low liter antibody to EB virus. The patient died with a bleeding diathesis terminally. Postmortem examinations confirmed the diagnosis of histiocytic medullary reticulosis.

An evaluation has been made of the EBV-IgA tests and the immune adherence hemagglutination assay (IAHA) as compared with standard diagnostic procedures in 119 serial sera from 22 clinical and 113 sera from 42 subclinical cases of EBV infectious mononucleosis. EBV-IgA antibody was demonstrable in 86.4 per cent of patients using EB3 cells as antigen and in 68.2 per cent with P3/HRIK cells. For heterophile antibody the IAHA test was more sensitive, gave higher titers, and was positive longer than the standard absorbed horse or sheep RBC tests in both clinical and subclinical EBV infections.