Evidence based criteria for the histopathological diagnosis of toxoplasmic lymphadenopathy.

AIMS: To formulate evidence based histopathological criteria for the diagnosis of acquired toxoplasmic lymphadenitis, in an area of high tuberculosis prevalence.

METHODS: Multiple histopathological parameters were assessed in a consecutive sample of biopsies from 68 patients presenting with lymphadenopathy with a duration of less than six months. Serum IgM enzyme linked immunosorbent assay was used as the standard reference test for the diagnosis of toxoplasmic lymphadenitis. The sensitivity, specificity, and likelihood ratios of various histological parameters were estimated.

RESULTS: The presence of microgranulomas (p < 0.0001), paracortical widening (p = 0.006), paracortical hyperplasia (p = 0.02), monocytoid B cells in sinuses (p = 0.007), lower than grade 2 macrogranuloma (p = 0.002), and the absence of giant cells (p = 0.05) were found to discriminate between IgM positive cases and IgM negative controls. Using a composite criterion-(1) presence of microgranulomas, (2) lower than grade 2 macrogranuloma, (3) absence of giant cells, and (4) follicular hyperplasia-toxoplasmic lymphadenitis can be diagnosed with a high degree of sensitivity (100%), specificity (96.6%), and positive likelihood ratio (29).

CONCLUSION: Toxoplasma lymphadenitis can be diagnosed with a high degree of confidence using the specific histopathological criteria identified here.