Sponge-like sonographic pattern of the spleen in immune dysregulation disorders

Although splenic ultrasound (US) assessment is periodically performed in most patients with inborn error of immunity (IEI), splenic microtexture has not been specifically investigated in this setting. We describe a newly described "sponge-like" splenic microtexture pattern in patients with different IEIs and hematologic immune dysregulation, and discuss its potential implications.

We present an index case (P1) followed by a cohort analysis including 26 patients with IEIs and 20 controls with chronic immune thrombocytopenia, for whom splenic microtexture data and iconography were available.

In P1, an 11-year-old patient with an autoimmune lymphoproliferative immunodeficiency phenotype, high-frequency splenic US revealed for the first time a "sponge-like" pattern, not visible with standard assessment, characterized by multiple hypoechoic round foci that persisted during long-term follow-up. In the IEI cohort, 46.2% of patients had splenomegaly, and a persistent sponge-like pattern was observed in 30.8% in the absence of infections or malignancies. In the control group, only one of 20 patients showed similar US features, transiently, during acute EBV infection. Immunomodulation (sirolimus, mycophenolate mofetil, rituximab) resulted in a significant improvement or normalization in all cases.

We report for the first time an association between splenic US microtexture features and IEIs. A persistent sponge-like pattern appears to be linked to IEIs/immune dysregulation, and the response to immunomodulation suggests a complex histopathological substrate. Although preliminary, our results suggest that, in patients with other signs of immune dysregulation/dysfunction, identification of this pattern could support earlier suspicion of an underlying IEI, after excluding infections and malignancies.