Maximum Diameter of Ileocecal Lymph Nodes Measured Using Abdominal Ultrasonography Allows for the Discrimination of Yersinia pseudotuberculosis Infection from Kawasaki Disease.

BACKGROUND This study aimed to determine whether the maximum diameter of ileocecal lymph nodes measured using abdominal ultrasonography is useful for differentiating Yersinia pseudotuberculosis infection from Kawasaki disease in the acute phase. The optimal maximum diameter cutoff of the ileocecal lymph nodes was also explored to optimize differentiation between these 2 diseases. METHODS We included pediatric patients <15 years old who met the diagnostic criteria for Kawasaki disease. Stool culture testing, loop-mediated isothermal amplification of stool specimens, and serological diagnosis were performed to confirm the presence or absence of Y. pseudotuberculosis infection. RESULTS Of the 122 patients included in the analysis, 17 were confirmed to have Y. pseudotuberculosis infection and 105 were not. The age (in months), white blood cell count, C-reactive protein level, prediction score (risk score) for nonresponse to intravenous immunoglobulin, and number of intravenous immunoglobulin doses did not differ significantly between the Y. pseudotuberculosis-positive and -negative groups. The maximum diameter of ileocecal lymph nodes was 6.0 (5.5-9.5) mm in the Y. pseudotuberculosis-positive group and 3.0 (2.5-3.8) mm in the Y. pseudotuberculosis-negative group (numbers presented as median, interquartile range), with a significantly larger diameter in the Y. pseudotuberculosis-positive group (P < 0.01, Mann-Whitney U test), suggesting potency of ultrasonography. CONCLUSION In patients meeting the diagnostic criteria for Kawasaki disease, the possibility of Y. pseudotuberculosis infection is significantly higher if the maximum ileocecal lymph node diameter ≥5.1 mm. Its sensitivity and specificity being 100%, and 89.5%, respectively.