Date Published: July 24, 2017
Publisher: Public Library of Science
Author(s): Eun Jung Shim, Kyung Mi Lee, Eui Jong Kim, Hyug-Gi Kim, Ji Hye Jang, Andres R. Floto.
The purpose of this study was to determine whether a CT interpretation with imaging pattern analysis differentiates Kikuchi disease (KD) from the two more frequently encountered differential lymph nodes diagnoses of tuberculous lymphadenopathy (TL) and reactive hyperplasia (RH).
Between January 2012 and July 2015, 20 patients with KD (6 men, 14 women; mean age, 27.80 years), 36 patients with RH (10 men, 26 women; mean age, 33.08 years) and 34 patients with TL (17 men, 17 women; mean age, 39.82 years) were pathologically diagnosed using US-guided fine needle aspiration biopsy, core needle biopsy, or surgical excisional biopsy. We recorded the total number, location, and size of the affected cervical lymph nodes, and two radiologists reviewed the characteristic imaging findings, including the presence of necrosis, cortical enhancement pattern, perinodal infiltration, conglomeration and nodal calcification, to form a consensus. In addition, we compared two attenuation indices on the nonnecrotic portion of the affected lymph nodes, nodal cortical attenuation (NCA) and the ratio of NCA to the adjacent muscle (NCA/M).
Conglomeration, enhancement pattern and NCA/M values were independent predictive CT features to distinguish KD from RH. Age and enhancement pattern discriminated KD from TL. Only the mean NCA/M value was a statistically significant CT feature (p = .008) in differentiating KD from both RH+TL. The mean NCA/M of KD (1.67 ± 0.20) was significantly higher than that of RH (1.49 ± 0.20) or TL (1.47 ± 0.21).
Our results indicate that in case of nonnecrotic lymphadenopathy, a higher NCA/M index can differentiate KD from RH and TL. In addition, the enhancement pattern according to the degree of necrosis discriminated between KD and TL in the case of necrotic lymphadenopathy.
Kikuchi disease (KD), which is also referred to as histiocytic necrotizing lymphadenitis or subacute necrotizing lymphadenitis, was first described by Kikuchi and Fujimoto et al. in 1972 . The etiology of KD is still unknown, but some reports suggest that viral infections or autoimmune diseases may be the causes [1,2]. KD is a benign form of lymphadenitis and spontaneously recovers within weeks to months, so an exact assessment is important to avoid unnecessary procedures and management [3,4]. However, a definitive diagnosis is often challenging, especially because KD has similar imaging features as other common types of cervical lymphadenopathy like tuberculous lymphadenopathy (TL), reactive hyperplasia (RH) of the lymph node, lymphomas, and metastases.
TL and KD have similar clinical presentations, including palpable cervical lesions with mild tenderness, low-grade fever, malaise, and night sweat [1,4,6]. However the natural course and the therapeutic methods for each are completely different. The treatment for TL usually consists of anti-tuberculosis medication and occasional surgical removal [2,6]. KD is self-contained and the lymphadenitis resolves within one to four months [1,6]. Therefore, many previous studies have tried to find indicators for the differential diagnosis a cervical lymphadenopathy using various imaging modalities, including CT, MRI, and US [3–8]. To the best of our knowledge, no research has so far reported cortical enhancement pattern analysis targeting nonnecrotic lymph nodes separately from necrotic ones to predict KD.