Trial Information

Ultrasonographic Differentiation Between Kikuchi's Disease and Lymphoma in Patients With Cervical Lymphadenopathy

Introduction Kikuchi's disease (KD) is a histiocytic necrotizing lymphadenitis that was
described for the first time in Japan in 1972 almost simultaneously by Kikuchi and
Fujimoto1-2. KD is a self-limited necrotizing lymphadenitis and occurs predominantly in
females between 20 and 30 years old. Its main presentation is cervical lymphadenopathy. The
diagnosis of KD is based on clinical manifestation, fine-needle aspiration cytology or
excision biopsy. The pathological characteristics include patchy paracortical
lymphohistiocytic aggregates with variable karyorrhexis and absence of granulocytic
infiltration. Antibiotics are not helpful symptoms remit within six months spontaneously.

As KD is a benign and self-limiting disease, proper diagnosis may help avoid unnecessary
treatment. KD can be easily confused clinically, pathologically, and radiologically with
malignant lymphadenopathy, especially lymphoma. Several reports have described the CT
characteristics of KD3-4, including enlarged, multiple lymph nodes that are homogeneously
enhanced without evidence of gross necrosis. The CT appearance of Kikuchi's disease may be
variable, thus mimicking lymphoma4. In previous work, the ultrasound appearance of KD has
not been well-described and has been compared to lymphoma. In this study, we compared the
sonographic characteristic of Kikuchi's disease and malignant lymphoma.

Patients and methods From November 2007 to September 2009, sonograms of twelve case notes
with pathological diagnoses of Kikuchi's disease and twelve patients with malignant lymphoma
were studied.

The sonograms were performed by the same sinologist (L-J Liao) using an ATL HDI 5000 with a
high-resolution 7.5- to 12-MHz real-time linear-array transducer (Philips Ultrasound,
Bothell, WA, USA). Morphological US parameters were thoroughly evaluated and recorded on the
Marosis PACS system (Marotech Inc., Seoul, South Korea). The lengths of short and long axes
of enlarged lymph nodes were measured and recorded. The shape of the lymph node was
determined by the short axis to long axis ratio (S/L ratio). The nodal border was assessed
for sharpness. Echogenicity of the lymph nodes was compared with that of adjacent muscles.
Swelling of the surrounding tissues that presented with hyperechoic rims was assessed. The
nodes were considered matted when a number of lymph nodes were clustered together. The
internal architecture of lymph nodes was examined for the presence of heterogeneous
micronodular pattern or reticulation.

Fisher's exact test and X 2 test were used to calculate the significance of the difference
in gray-scale features. Mann-Whitney U tests were used to calculate the significance of the
difference in nodal size and short- to long-axis ratio.

Expected Results:

We suppose that basic ultrasonographic characteristics (size, shape, rims, matting, and
micronodular echotexture) help in the differentiation of cervical lymph nodes in patients
with Kikuchi's disease and lymphoma. A precise diagnosis of KD is possible avoiding
unnecessary biopsies or aggressive treatment.

References:

1. Kikuchi M. Lymphadenitis showing focal reticulum cell hyperplasia with nuclear debris
and phagocytosis. Nippon Ketsueki Kakkai Zasshi 1972;35:379-80.

2. Fujimoto Y, Kozima Y, Yamaguchi K. Cervical subacute necrotizing lymphadenitis. A new
clinicological entity. Naika 1972;376:247-53.

3. Kwon S, Kim T, Kim Y, Lee K, Lee N, Seol H. CT findings in Kikuchi disease: analysis of
96 cases. American Journal of Neuroradiology 2004;25(6):1099.

4. Na D, Chung T, Byun H, Kim H, Ko Y, Yoon J. Kikuchi disease: CT and MR findings.
American Journal of Neuroradiology 1997;18(9):1729.