Kikuchi-Fujimoto disease following SARS-CoV-2 vaccination

Abstract

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.

Keywords: COVID-19; Medical education; Vaccination/immunisation.

Figure 1

Timeline of clinical progress. CRP, C reactive protein; ESR, erythrocyte sedimentation rate; LO, lactate dehydrogenase; PSL, prednisolone; WBC, white blood cells.

Figure 2

CT findings. CT scans showed lymphadenopathy in the (A) bilateral cervical regions, (B) left supraclavicular fossa, (C, D) bilateral axillae and (E) right inguinal region (white arrow) as well as (F) hepatosplenomegaly.

Figure 3

Histopathologic findings. The patient underwent an excisional right inguinal lymph node biopsy. (A) Large and small foci and fusion of histiocytes and lymphocytes were seen from the paracortex to the cortex of the lymph node. Apoptosis and nuclear debris were observed in the central part of the lesion, and abundant histiocytes were phagocytosing this debris. No neutrophils or eosinophils were seen. Immunostaining showed an increase in (B) CD3+, (C) CD4+, and (D) CD8+ T cells and (E) CD68+ histiocytes. (F) No CD20+ B cells were seen. Histopathological features of the lymph nodes of patients with Kikuchi-Fujimoto disease include numerous phagocytic histiocytes, lymphocytes, marked nuclear debris and apoptosis. Neutrophils and eosinophils are generally absent. Immunohistological findings predominately comprise CD68+ histiocytes, CD4+ T cells and CD8+ T cells, with few B cells. These findings confirmed histiocytic necrotising lymphadenitis in the present case.