Sangmin Lee, Presenter: Nothing to Disclose

Jeong Hyun Yoo MD, PhD, Abstract Co-Author: Nothing to Disclose

Sook Yun Song, Abstract Co-Author: Nothing to Disclose

Kyungmin Roh, Abstract Co-Author: Nothing to Disclose

Kikuchi’s disease (KD) and tuberculous lymphadenitis (TL) have been known to have nodal necrosis commonly, and it is often difficult to differentiate between them. The purpose of this study is to evaluate necrotic pattern on CT findings for the differentioation between them.

We included 21 patients (F: M =12:9, mean age: 23) with KD and 21 patients (F: M=18:3, mean age: 35) with TL underwent CT of the neck and histologically confirmed by excision biopsy. Two radiologists retrospectively accessed presence of necrosis; the extent, number, location, margin, Hounsfield Unit (H.U) of the necrotic foci, and perinodal infiltration. Necrotic extent was classified mild (< 30% of affected lymph node area), moderate (30-70%), and severe (>70%). H.U. number was measured in the necrotic portion and adjacent muscle on pre- and post-contrast images, and ratio was calculated. Mann-whitney U test and χ2 tests were used for comparison of two group and stepwise multivariate logistic regression analysis was also performed a to evaluate the predictive features.

Seventeen patients (91%) with KL and all patients with TL shows necrotic portion. Extent of necrosis was mild or moderate in 82% KD and severe in 67% TD (p<.001). Nientyfour percent of patients with KD had multiple necrotic foci, while 62% patients with TL had single necrotic focus (p<.000). Necrotic foci were located in peripheral(35%),  central(12%) , and combined portion (53%) with KD, and in peripheral (10%), central (52%), and combined portion(38%) with TL (p=.019). The margins of necrotic foci were indistinct in 82% with KD and relatively well-defined or well-defined in  86% patients with TL(p<.000). H.U. number of the necrosis of KD on the post-contrast image (71HU±17) was significantly higher than that of TL (42HU±21) (p<.000), and the H.U. ratio between the necrosis and adjacent muscle of KD was also significantly higher than that of TL (p=0.002). Perinodal infiltration was more frequent in KD (86%) than TL (30%) (p<.005). Stepwise multivariate logistic regression revealed the margin of necrotic foci to be an independent predictor (R=.689, p<.000). Indistinct margin of necrotic foci can differentiate KD from TL with the accuracy of 84%.

Necrosis patterns, especially the margin of necrotic foci, had the high accuracy for differentiation of KD and TL.

CT can demonstrate necrosis pattern in lymph node.

Lee, S, Yoo, J, Song, S, Roh, K, Roles of Necrosis Pattern on CT in Differentiation Kikuchi Lymphadenitis from Tuberculous Lymphadenitis.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9009216.html