Atypical Kikuchi-Fujimoto Disease: FDG-PET Contribution To The Diagnosis

Abstract

Kikuchi-Fujimoto disease (KFD), also called histiocytic necrotizing lymphadenitis, is more common in young women and typically presents with small, painful, localized cervical lymphadenopathy that resolves spontaneously within a few weeks. Laboratory findings are variable. As many as 40% of KFD cases are reported to be painless, and up to 22% to be generalized lymphadenopathy. Therefore, malignant lymphoma could be a differential diagnosis of KFD. A histopathologic diagnosis is needed when it is difficult to distinguish KFD from lymphoma. KFD typically shows small, highly accumulated cervical lymph nodes on fluorodeoxyglucose positron emission tomography (FDG-PET). This contrasts with malignant lymphoma, which tends to be associated with massive lymphadenopathy. In our case, a 40-year-old Japanese male presented with painless lumps in the right neck, accompanied by fever, night sweats, and loss of appetite. His symptoms and laboratory results worsened over a month. FDG-PET revealed highly accumulated uptake in cervical, mediastinal, and axillary lymph nodes. The PET imaging showed a small, high FDG uptake and contributed to the correct diagnosis of KFD. This case report highlights the importance of FDG-PET, which is a valuable diagnostic tool for KFD as it typically differentiates large clusters of small lymph nodes typical of KFD from normal lymph nodes.

Learning points: Kikuchi-Fujimoto disease (KFD) typically presents with small, painful, localised cervical lymphadenopathy.KFD has atypical patterns showing painless and generalised lymphadenopathy.Fluorodeoxyglucose positron emission tomography (FDG-PET) could be useful for diagnosing not only malignant lymphoma but also KFD.

Keywords: Bentall procedure; Type A aortic dissection; atypical symptoms.

Figure 1

Ultrasound scan of the right neck showed approximately 1 cm lymph nodes. Short-to-long axis ratio was 0.42 with normal nodal hilus.

Figure 2

FDG-PET showed highly accumulated uptake in the lymph nodes of the mediastinum as well as the neck and axillary region.

Figure 3

Histopathological features showed no atypical cells; (A) blastoid cells, (B) diffuse foci of necrotic tissue with karyorrhexis and (C) apoptosis were noted, which are definitive indicators of KFD.