Wednesday, December 7, 2011

Kikuchi-Fujimoto Disease

Kikuchi-Fujimoto disease, also known as Kikuchi disease and histiocytic necrotizing lymphadenitis lymphadenitis, is a rare, self-limiting condition characterized by characterized by lymphadenopathy, fever, and neutropenia.

Its cause is unknown. Viral etiologies have been proposed, with the usual suspects (EBV, HHV 6 and 8) included in the lineup. An autoimmune mechanism has also been suggested, supported by a strong association with systemic lupus erythematosus and mixed connective tissue disorders.

Patients are typically girls or young women under 30 years of age. The most common presentation is firm, tender, unilateral cervical lymphadenopathy. Patients may also have more generalized adenopathy, low-grade fever, malaise, fatigue, diarrhea, weight loss, nausea, and vomiting. Kikuchi-Fujimoto disease generally has a benign, self-limited course with symptoms lasting between 1–2 months.

Patients can have nonspecific laboratory findings such as neutropenia with atypical lymphocytes, anemia, and elevated rythrocyte sedimentation rate (ESR), lactogen dehydrogenase (LDH), and transaminases. Diagnosis, however, can be made with biopsy revealing effaced nodal architecture with islands of hyperplasia and zonal necrosis. Fine needle aspiration can also be used.

Imaging findings overlap with those of lymphoma, and biopsy cannot be avoided. As noted above, the lymphadenopathy is more commonly found in the neck, where it is more often unilateral. Cervical lymph nodes range in size from 0.5–3.5 cm and the majority of patients show perinodal fatty infiltration and homogeneous nodal contrast enhancement. A minority of cases have lymph nodes with low-attenuation areas, sometimes resulting in ring-shaped lymph nodes mimicking tuberculosis or metastatic lymphadenopathy.

The images above are from a 50-year-old woman with diffuse lymphadenopathy and "mildly positive ANA." Cervical, mediastinal, hilar, and axillary lympahdenopathy was noted, without evidence of retroperitoneal or pelvic lympahdenopathy. Nodal enhancement was homogeneous. Mild perinodal infiltration is well seen in a left level IIA lymph node (red *)


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