[Kikuchi-Fujimoto disease mimicking malignant lymphoma in adolescents]

Kikuchi-Fujimoto disease following SARS-CoV-2 vaccination

A previously healthy Japanese woman in her 20s was admitted to our hospital with a 2-week history of fever (39.0°C) and a 1-week history of painful cervical lymphadenopathy. The day before fever onset, she had received her first Pfizer-BioNTech SARS-CoV-2 vaccine in her left arm. She had previously been treated with empirical antibiotics with no improvement. Physical examination revealed painful lymphadenopathy in both posterior cervical regions. CT showed symmetrical lymphadenopathies in the neck, supraclavicular, axillary and inguinal regions as well as hepatosplenomegaly. We suspected lymphoma and performed a lymph node biopsy in the right inguinal region, which revealed necrotising histiocytic lymphadenitis. The patient was, therefore, diagnosed with Kikuchi-Fujimoto disease (KFD). She improved after the corticosteroid therapy. This report highlights the importance of including KFD as a differential diagnosis of lymphadenopathy after SARS-CoV-2 vaccination. Additionally, lymph node biopsy is helpful for diagnosing KFD because it rules out other entities.

Positron emission tomography/computed tomography hypermetabolism of Kikuchi-Fujimoto disease mimicking malignant lymphoma: a case report and literature review

Kikuchi–Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, is a benign, self-limiting inflammatory disorder of unknown etiology and pathogenesis. This report presents a rare case involving a man with ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) hypermetabolism caused by KFD mimicking malignant lymphoma. The PET/CT maximum intensity projection showed multiple hypermetabolic lymphadenopathies and homogeneous FDG uptake in the bone marrow and spleen. Malignant lymphoma was initially suspected. The patient then underwent excision biopsy of one enlarged right cervical lymph node that was selected because it showed the highest FDG uptake in PET/CT, and examination of this biopsy specimen confirmed the diagnosis of KFD. PET/CT is useful for assessing the general condition of patients and can help to select lymph nodes for excision biopsy based on the highest FDG uptake. However, KFD can predispose to localized FDG uptake and limit the specificity of PET/CT by mimicking malignancy. Thus, positive results of PET/CT should be interpreted with caution.

Kikuchi-Fujimoto disease: a case report and the evaluation of diagnostic procedures

BACKGROUND

Kikuchi-Fujimoto disease, known as histiocytic necrotizing lymphadenitis, is a benign, self-limiting and systemic disorder involving lymph nodes with unknown aetiology. First reported in Japan, there has been an increase in its incidence globally. Because of its non-specific clinical features, the disease can be easily mistaken for other forms of lymphadenitis with a high rate of misdiagnosis and mistreatment, posing a considerable challenge.

CASE PRESENTATION

A case of young Chinese woman with fever and cervical lymphadenopathy is presented. Physical examinations and imaging techniques were used to rule out common forms of lymphadenitis (e.g. cat-scratch disease and tuberculous lymphadenitis). Laboratory tests were then conducted to exclude others such as systemic lupus erythematosus and non-Hodgkin lymphoma. After Kikuchi-Fujimoto disease was identified, the patient was managed with symptomatic treatments. Our case was compared with relevant cases in the literature. A diagnostic flow chart was proposed to facilitate the diagnosis and treatment.

CONCLUSIONS

With its shared clinical features, Kikuchi-Fujimoto disease can be mistaken for other forms of lymphadenitis. A combined use of medical imaging and laboratory tests is the effective way to avoid misdiagnosis.