Clinical features of histiocytic necrotizing lymphadenitis in children.

Due to its nonspecific clinical characteristics, histiocytic necrotizing lymphadenitis (HNL) is often misdiagnosed as a suppurative cervical lymphadenitis and lymphoma. Thus, this study aimed to investigate the clinical characteristics of HNL in pediatric patients. We retrospectively identified 61 patients with histopathologically confirmed HNL. Clinical and laboratory data, including age, sex, clinical manifestations, laboratory investigations, histological discoveries, treatment, and outcomes, were collected from the medical records to determine associations with extracervical lymph node (LN) involvement. The mean age of patients was 9.7 ± 2.8 years (range, 1.5-14.0 years), and the male-to-female ratio was 2.2:1. The most common systemic symptom was fever in all patients. The median pre-admission and total durations of fever were 13.0 (interquartile range [IQR]: 9.0-22.5 days) and 22.0 days (IQR: 17.0-33.0 days), respectively. Patients with temporary fever (< 2 weeks) had a higher peak temperature and were more likely to undergo LN biopsy after admission than those with a prolonged fever (≥ 2 weeks). Multivariate analysis revealed that peak temperature ≥ 40 °C was significantly associated with a longer fever duration (P = 0.023). Laboratory values showed leukopenia (68.9%), which presented more frequently in solitary cervical LNs than in extracervical LNs (82.4% vs. 52.9%, p = 0.027) in patients with prolonged fever. CONCLUSIONS: HNL is often misdiagnosed in older children with persistent fever and lymphadenopathy, leading to unnecessary diagnostic tests and evaluations, inappropriate antibiotic administration, and mismanagement. A multidisciplinary team, including primary care providers, rheumatologists, and pathologists, can improve patient outcomes by increasing their awareness of this rare condition. WHAT IS KNOWN: • Histiocytic necrotizing lymphadenitis (HNL) is characterized by fever, leukopenia, and neck lymphadenopathy with unknown etiology. • The lack of neutrophils or eosinophils in the histology, immunohistochemistry results help distinguish HNL from infectious causes. Although HNL is a self-limiting disease, antibiotics and steroid treatments were used inappropriately. WHAT IS NEW: • A fever peak ≥ 40 °C was associated with a longer fever duration in HNL patients. Leukopenia presented more frequently in solitary cervical lymph node (LNs) than in extracervical LNs inpatients with prolonged fever. • Steroids are not recommended as a routine treatment, however, in some severe or relapsing cases with persistent symptoms, prednisolone (5 mg twice a day for 2 days) or other steroids (an equivalent dose of prednisolone) responded favorably.

Kikuchi-Fujimoto disease during early pregnancy.

Kikuchi-Fujimoto disease (KFD) is rare during pregnancy. It is characterized by necrotizing lymphadenitis and often occurs in young Asian women. We report a case of KFD during pregnancy, which was difficult to diagnose. A 37-year-old pregnant female (gestational week [GW] 7+5) was admitted to our hospital because of hyperemesis gravidarum. On the eighth day of hospitalization (GW 8+6), she suddenly developed a fever (38.0°C) with skin rash and posterior pharynx redness. Blood tests showed pancytopenia and abnormal liver function. The patient was misdiagnosed with severe Epstein-Barr virus infection and administered with prednisolone. Subsequently, cervical lymphadenopathy was observed, and biopsy results led to the diagnosis of KFD. Thereafter, her symptoms improved, and she was discharged at GW 13+4. KFD must be included as a differential diagnosis for patients with fever, abnormal liver function, and pancytopenia during pregnancy.

[Clinical characteristics and treatment in adults and children with histiocytic necroti-zing lymphadenitis].

OBJECTIVE: To analyze the clinical data of histiocytic necrotizing lymphadenitis(HNL), comparing the similarities and differences between children and adults, to deepen the understanding of the disease by clinical physicians, and to improve diagnostic rate and reduce misdiagnosis and mistreatment. METHODS: The clinical data of hospitalized patients with histiocytic necrotizing lymphadenitis diagnosed by biopsy from January 2010 to August 2023 in Peking University First Hospital were collec-ted, and the clinical features, laboratory examinations, pathological features, treatments with antibiotics and glucocorticoids, and prognosis of histiocytic necrotic lymphadenitis were analyzed. Grouped based on age, the differences of clinical characteristics, laboratory tests, treatment, and prognosis between the children group (< 16 years old) and the adult group (≥16 years old) were compared. RESULTS: Among the 81 enrolled patients, there were 42 males and 39 females. The median age was 21(14, 29) years, the median duration of disease was 20.0(13.0, 30.0) days, and the median length of hospital stay was 13.0 (10.0, 15.0) days. The first symptoms were fever, lymphadenopathy, and both. All the patients had enlarged lymph nodes with different parts and sizes, 96.3% (78 of 81) of the patients had cervical lymphadenopathy, 50.6% (41 of 81) had bilateral cervical lymphadenopathy, 55.6% (45 of 81) had supraclavicular, axillary or inguinal lymphadenopathy, and the median lymph node diameter was 20.0(20.0, 30.0) mm. Only one patient had no fever, the other 80 patients had fever, the median peak body temperature was 39.0(38.0, 39.8) ℃. Accompanying symptoms: rash (8.6%, 7/81), fatigue (34.6%, 28/81), night sweating (8.6%, 7/81), chills (25.3%, 25/81), muscle soreness (13.6%, 11/81), and joint pain (6.2%, 5/81). There were 17 cases (21.0%, 17/81) of hepatosplenomegaly, of which 12 cases (70.6%, 12/17) were splenomegaly. 68.8%(55/80) of patients had a decrease in white blood cell (WBC) count, with 47.5%(38/80)increased in lymphocyte(LY)proportion, 53.4%(39/73) increased in high-sensitivity C-reactive protein(CRP), 79.2%(57/72) increased in erythrocyte sedimentation rate(ESR), 22.2%(18/81) increased in alanine transaminase(ALT), 27.2%(22/81) elevated in aspartate transaminase(AST), and 81.6%(62/76) elevated in lactate dehydrogenase(LDH). All the 81 patients underwent lymph node biopsy, and 77.8%(63/81) of the patients showed that most of the structures in the lymph nodes were destroyed or disappeared, and 16.0%(13/81) of the lymph nodes were still in existence, hyperplasia and normal lymph node were 1.2%(1/81) respectively, and 3.7%(3/81) had normal lymph node structures. Immunohistochemical staining was performed in 67 cases. The percentages of CD3+ and CD68(KP1)+ were respectively 97.0%(65/67), and MPO+ were 94.0%(63/67). In the study, 51 patients (63.0%, 51/81) were treated with glucocorticoid therapy after diagnosis. The median time for temperature to return to normal was 1.0(1.0, 4.0) days after glucocorticoid therapy. when the glucocorticoid treatment worked best, the body temperature could drop to normal on the same day. There were significant differences in length of stay, predisposing factors, chills, the rate of increase in high-sensitivity CRP, antibiotic and glucocorticoid treatment between the adults and children groups (P < 0.05). CONCLUSION: In clinical practice, if there are cases with unexplained fever, superficial lymph node enlargement, and reduced white blood cells as clinical characteristics, and general antibiotics treatment is ineffective, histiocytic necrotic lymphadenitis should be considered. Lymph node biopsy should be performed as early as possible to clarify the diagnosis, reduce misdiagnosis and mistreatment, and symptomatic treatment should be the main treatment. Glucocorticoids therapy has a definite therapeutic effect.

Characterization of Kikuchi-Fujimoto Disease in Children and Risk Factors Associated with Its Course.

OBJECTIVE: To outline the characteristics of Kikuchi-Fujimoto disease (KFD) in children and analyze factors associated with severe and recurring courses. METHODS: Electronic medical records of children histopathologically diagnosed with KFD at Seoul National University Bundang Hospital from March 2015 to April 2021 were retrospectively reviewed. RESULTS: A total of 114 cases (62 males) were identified. The mean patient age was 12.0 ± 3.5 years. Most patients came to medical attention with cervical lymph node enlargement (97.4%) and fever (85%); 62% had a high-grade fever (≥39°C). Prolonged fever (≥14 days) was seen in 44.3% and was associated with a high-grade fever (P = .004). Splenomegaly, oral ulcer, or rash was present in 10.5%, 9.6%, and 15.8%, respectively. Laboratory findings showed leukopenia, anemia, and thrombocytopenia in 74.1%, 49%, and 24%, respectively. Sixty percent of cases had a self-limited course. Antibiotics were initially prescribed in 20%. A corticosteroid was prescribed in 40% of patients and was associated with oral ulcer (P = .045) and anemia (P = .025). Twelve patients (10.5%) had a recurrence with a median interval of 19 months. No risk factor for recurrence was identified in multivariable analysis. Clinical characteristics of KFD were similar between our current and previous studies. However, antibiotics use decreased (P < .001); nonsteroidal anti-inflammatory drugs use increased (P < .001), and, although statistically not significant, corticosteroid treatment also increased. CONCLUSIONS: Over a span of 18 years, the clinical characteristics of KFD did not change. Patients presenting with high-grade fever, oral ulcer, or anemia may benefit from corticosteroid intervention. All patients should be monitored for recurrence.

Kikuchi disease with an exuberant proliferation of large T-cells: a study of 25 cases that can mimic T-Cell lymphoma.

Exuberant large T-cell proliferations in Kikuchi disease can potentially be misdiagnosed as lymphoma. In this study, we explore their clinicopathological features and summarize key points that can be used to distinguish them from T-cell lymphoma. The cohort consisted of 25 cases of Kikuchi disease with an exuberant large T-cell proliferation, which, in part, mimicked lymphoma. The median age was 25 years with a female:male ratio of 4:1. By B-scan ultrasonography, patients presented with either isolated lymphadenopathy (68%) involving the cervical and axillary regions or generalized lymphadenopathy (32%). Histologically, lymph nodes showed paracortical and interfollicular expansion by sheets of large cells associated with karyorrhectic debris. Histiocytes and plasmacytoid dendritic cells were present in the background. No case showed complete effacement of lymph node architecture. The large cells were CD8-positive cytotoxic T-cells with a high proliferation rate. These T-cells showed decreased BCL-2 in 17 (68%) cases. CD5 expression was decreased in 10 (40%) cases. Histiocytes in the background were positive for myeloperoxidase. Clonal TRG and/or TRB rearrangements were detected in 2 of 10 (20%) cases. In conclusion, large T-cell proliferations in Kikuchi disease can be alarming at the morphologic and immunophenotypic levels and need to be distinguished from T-cell lymphoma. Clinical features helpful in the differential diagnosis include young patients and lymphadenopathy involving the cervical and axillary regions. Major pathologic features helpful in this differential diagnosis include partial involvement of the lymph node and the presence of karyorrhectic debris, crescent-shaped histiocytes, and/or loose aggregates of plasmacytoid dendritic cells.

Clinical scoring approach for detection of histiocytic necrotising lymphadenitis in adults.

BACKGROUND: Histiocytic necrotising lymphadenitis (HNL) is rare and can be easily ignored. AIMS: To summarise the characteristics of HNL and find a simple scoring approach to detect HNL in adult patients. METHODS: Adult patients with lymphadenopathy diagnosed by lymph node biopsy were enrolled. Chi-squared test and t-test were used to determine the significant variables. The cut-off values and scores assigned to each factor were performed by receiver operating characteristic (ROC) curves and coefficients in the logistic regression respectively. The performance of the scoring system was evaluated by ROC curves. RESULTS: There were 32 HNL cases and 1162 other cases in the present study. These features, including age, the frequency of presentations of fever, cervical and painful lymph nodes, decrease of white blood cells (WBC), ratio of neutrophil to WBC (N ratio) and elevated lactate dehydrogenase (LDH), were different between patients with HNL and other diseases. Based on the multivariate analysis, the scoring approach was defined as follows: score = 3 (fever) + 2 (cervical lymphadenopathy) + 2 (decreased WBC) + 1 (decreased N ratio) + 2 (elevated LDH). The cut-off was score 4. This approach performed will detect HNL with an area under the curve of 0.889. CONCLUSION: The present study suggests that the novel scoring approach we put forward might be useful to detect HNL in adult patients though further studies are needed.

Hemophagocytic lymphohistiocytosis and histiocytic necrotizing lymphadenitis secondary to hemodialysis catheter-related bloodstream infection caused by Corynebacterium Striatum.

BACKGROUND: We herein described the coexistence of hemophagocytic lymphohistiocytosis (HLH) and histiocytic necrotizing lymphadenitis, alternatively known as the Kikuchi disease (KD), secondary to hemodialysis catheter-related bloodstream infection (BSI) caused by Corynebacterium striatum. CASE PRESENTATION: A patient on maintenance hemodialysis had developed persistent fever and Corynebacterium striatum was subsequently identified from the culture of both catheter tip and peripheral blood. During mitigation of the BSI, however, his fever was unabated and ensuing workup further found thrombocytopenia, hyperferritinemia, hypertriglyceridemia, low NK cell activity and a surge in serum CD25 levels. Moreover, biopsy of the bone marrow and lymph node detected histopathological evidence of hemophagocytosis and KD, respectively. Upon these abnormalities, the title-bound diagnosis was considered and the patient was eventually recovered from the treatment of dexamethasone instead of antibiotics. Consistently, aberrations in his serum CD25 levels and NK cell activity had subsided two months after discharge. CONCLUSIONS: Arguably, this encounter offered a unique chance to unravel the principal pathogenic cascade in immunobiology that made the three entities one disease continuum. As such, our work may add new understandings of HLH and/or KD secondary to severe infections in general and excessive release of cytokines in particular among patients with kidney diseases. The resultant early diagnosis is crucial to initiate appropriate treatment and improve the survival of patients with these challenging and potentially life-threatening disorders.

Kikuchi-Fujimoto disease is mediated by an aberrant type I interferon response.

Kikuchi-Fujimoto disease (KFD) is a reactive lymphadenitis of unclear etiology. To understand the pathogenesis of KFD, we performed targeted RNA sequencing of a well-characterized cohort of 15 KFD specimens with 9 non-KFD lymphadenitis controls. Two thousand and three autoimmunity-related genes were evaluated from archived formalin-fixed paraffin-embedded lymph node tissue and analyzed by a bioinformatics approach. Differential expression analysis of KFD cases compared to controls revealed 44 significantly upregulated genes in KFD. Sixty-eight percent of these genes were associated with the type I interferon (IFN) response pathway. Key component of the pathway including nucleic acid sensors, IFN regulatory factors, IFN-induced antiviral proteins, IFN transcription factors, IFN-stimulated genes, and IFN-induced cytokines were significantly upregulated. Unbiased gene expression pathway analysis revealed enrichment of IFN signaling and antiviral pathways in KFD. Protein-protein interaction analysis and a molecular complex detection algorithm identified a densely interacting 15-gene module of type I IFN pathway genes. Apoptosis regulator IFI6 was identified as a key seed gene. Transcription factor target analysis identified enrichment of IFN-response elements and IFN-response factors. T-cell-associated genes were upregulated while myeloid and B-cell-associated genes were downregulated in KFD. CD123+ plasmacytoid dendritic cells (PDCs) and activated T cells were noted in KFD. In conclusion, KFD is mediated by an aberrant type I interferon response that is likely driven by PDCs and T cells.

A Malignant Mimicker: Features of Kikuchi-Fujimoto Disease in the Pediatric Population.

BACKGROUND: Kikuchi-Fujimoto disease (KFD) is a rare, benign, and self-limited disease that presents with cervical lymphadenopathy and systemic symptoms. Histologic evaluation is often necessary to differentiate KFD from other entities. METHODS: Electronic medical records and diagnostic material were reviewed for 14 children diagnosed with KFD and 6 children diagnosed with infectious mononucleosis (IM) from 2013-2021. Four cases of KFD were further characterized using targeted DNA-based next-generation sequencing. RESULTS: Systemic symptoms were present in 86% (n = 12/14) of KFD patients, the most common being fever. Laboratory values worrisome for malignancy included cytopenia(s) (n = 9/12), elevated ESR and/or CRP (n = 9/12), elevated ferritin (n = 7/7), and elevated LDH (n = 7/10). Histologically, lymph nodes showed characteristic necrotic foci without neutrophils surrounded by MPO+ "crescentic" histiocytes. Immunoblasts and CD123+ plasmacytoid dendritic cells (pDCs) were also increased surrounding the necrosis. IM lymph nodes showed similar features when necrosis was present but increases in pDCs were patchy and rare neutrophils were seen in the necrotic foci. Molecular analysis of 4 KFD cases did not identify pathogenic variants. CONCLUSION: While the signs/symptoms of KFD are worrisome, there are pathologic features that help differentiate it from potential mimics. We did not identify characteristic molecular features to aid in the work-up of these cases.

Encephalitis in Kikuchi-Fujimoto disease being immune-mediated.

INTRODUCTION: Histiocytic necrotizing lymphadenitis, also known as Kikuchi-Fujimoto disease, is a rare benign self-limiting inflammatory disease often seen in young adults. The main clinical features are fever with cervical lymphadenopathy. Neurological complications of Kikuchi-Fujimoto disease were occasionally reported although the specific pathogenesis was not clear. The condition could be severe when encephalitis coexists. METHODS: Here we reported a young case of Kikuchi-Fujimoto disease with subsequent severe autoimmune encephalitis. RESULTS: The symmetric striatal and limbic MRI lesions combined with psycho-cognitive, epileptic symptoms supported encephalitis. Tissue-based immunofluorescence revealed widely cytoplasmic fluorescence in rat cerebellar and hippocampal neurons, which provide evidence for immune-mediated encephalitis. The clinical outcome was satisfactory after immunosuppressive therapy with MRI lesions largely disappeared. CONCLUSION: The encephalitis complication of Kikuchi disease may be autoimmune and mediated by cytotoxic T cells.

Kikuchi-Fujimoto disease as the initial manifestation of systemic lupus erythematosus complicated with macrophage activation syndrome: two case reports and a review of literature.

BACKGROUND: Kikuchi-Fujimoto disease (KFD) is a self-limiting and benign disease characterized by cervical lymphadenopathy and fever. Although KFD should be made differentially diagnosed from infectious, autoimmune, and malignant diseases, it sometimes occurs in patients with systemic lupus erythematosus (SLE) and can be complicated with macrophage activation syndrome (MAS). However, it is rare that KFD is the initial manifestation of SLE and to be complicated with MAS. CASE PRESENTATION: A 9.6-year-old girl presented with high-grade fever, double-side cervical lymphadenopathy with mild pain of one week, leukopenia, alopecia, and rash on the cheek. During hospitalization, laboratory investigations showed positive antinuclear antibody (ANA), low complement 3 (C3), and low complement 4 (C4). Imaging investigations showed pleural and pericardial effusion. A 10.3-year-old girl presented with intermittent high-grade fever, double-sided cervical lymphadenopathy with obvious pain of 1-month duration, and discoid lesion on the cheek. During hospitalization, laboratory investigations showed positive ANA, leukopenia, thrombocytopenia, anemia with positive Coombs' test, low C3, and positive Smith antibodies. Both cases were diagnosed with KFD using lymph node biopsy, simultaneously fulfilling the diagnostic criteria of SLE. Subsequently, the two girls became complicated with MAS, followed by interstitial lung disease and neuropsychiatric lupus, respectively. Both patients benefited from high-dose methylprednisolone pulse therapy combined with intravenous cyclophosphamide. CONCLUSIONS: More attention should be paid to differential diagnosis, especially SLE, in children diagnosed with KFD. In addition, children with SLE who presented with KFD as the initial manifestation seem to have a higher risk of developing MAS and experiencing organ involvement.

Hemophagocytic Lymphohistiocytosis Associated with Histiocytic Necrotizing Lymphadenitis: A Clinical Study of 13 Children and Literature Review.

OBJECTIVE: To analyze the clinical characteristics and prognosis of pediatric hemophagocytic lymphohistiocytosis (HLH) associated with histiocytic necrotizing lymphadenitis (HNL). STUDY DESIGN: We retrospectively collected the clinical data of all children with HNL-HLH enrolled in Beijing Children's Hospital from 2007 to 2019. The control patients with Epstein-Barr virus-associated HLH and simple HNL (not associated with HLH) were case matched (1:2). The clinical features and prognosis were analyzed by case-control study. Cases of HNL-HLH in the literature were reviewed. RESULTS: The male-to-female ratio of the 13 patients in our center was 9:4. The mean age of the patients at disease onset was 8.1 ± 1.2 years, younger than that of the 16 patients in the literature (P = .017). Clinical presentations, especially rash and splenomegaly, and laboratory examination of HNL-HLH group were statistically different from Epstein-Barr virus-HLH group, simple HNL group, and patients reported in the literature (P < .05). Three patients were treated with immunosuppressive drugs or chemotherapy owing to poor control of HLH. One patient died, and all 12 remaining patients survived, 2 of which developed autoimmune diseases. Kaplan-Meier survival curves showed no statistical difference among the 3 groups (P > .05). CONCLUSIONS: HNL-HLH is more common in school- and preschool-age children. Most patients have a favorable prognosis. Some patients suffer from relapses or develop autoimmune diseases. Prolonged follow-up should be carried out for patients with HNL-HLH.

Distinguishing lupus lymphadenitis from Kikuchi disease based on clinicopathological features and C4d immunohistochemistry.

OBJECTIVES: Distinguishing Kikuchi disease (KD) from lupus lymphadenitis (LL) histologically is nearly impossible. We applied C4d immunohistochemical (IHC) stain to develop diagnostic tools. METHODS: We retrospectively investigated clinicopathological features and C4d IHC staining in an LL-enriched development cohort (19 LL and 81 KD specimens), proposed risk stratification criteria and trained machine learning models, and validated them in an external cohort (2 LL and 55 KD specimens). RESULTS: Clinically, we observed that LL was associated with an older average age (33 vs 25 years; P=0.005), higher proportion of biopsy sites other than the neck [4/19 (21%) vs 1/81 (1%); P=0.004], and higher proportion of generalized lymphadenopathy compared with KD [9/16 (56%) vs 7/31 (23%); P=0.028]. Histologically, LL involved a larger tissue area than KD did (P=0.006). LL specimens exhibited more frequent interfollicular pattern [5/19 (26%) vs 3/81 (4%); P=0.001] and plasma cell infiltrates (P=0.002), and less frequent histiocytic infiltrates in the necrotic area (P=0.030). Xanthomatous infiltrates were noted in 6/19 (32%) LL specimens. Immunohistochemically, C4d endothelial staining in the necrotic area [11/17 (65%) vs 2/62 (3%); P<10-7], and capillaries/venules [5/19 (26%) vs 7/81 (9%); P=0.048] and trabecular/hilar vessels [11/18 (61%) vs 8/81 (10%); P<10-4] in the viable area was more common in LL. During validation, both the risk stratification criteria and machine learning models were superior to conventional histological criteria. CONCLUSIONS: Integrating clinicopathological and C4d findings could distinguish LL from KD.

Identification of genes associated with Kikuchi-Fujimoto disease using RNA and exome sequencing.

Kikuchi-Fujimoto disease (KFD) is an extremely rare disease, and although it is reported to have a worldwide distribution, young Asian women are most likely to be affected. Although this disease is generally benign and self-limiting, distinguishing it from other diseases that cause lymphadenopathy (e.g., leukemia, lymphoma, and infectious diseases) is challenging. A lymph node biopsy is a definitive diagnostic technique for KFD and only requires skillful pathologists. There are no specific symptoms or laboratory tests for KFD, and more than 50% of KFD patients have suffered from being misdiagnosed with lymphoma, which leads to improper treatment. In this study, lymph node tissue samples from KFD patients were used to reveal their exomes and transcriptomes using a high-throughput nucleotide sequencer. Fourteen single nucleotide polymorphisms (SNPs) were identified as candidate KFD markers and were compared with a healthy lymph node exome dataset. The mutation of these genes caused disruptive impact in the proteins. Several SNPs associated with KFD involve genes related to human cancers, olfaction, and osteoblast differentiation. According to the transcriptome data, there were 238 up-regulated and 1,519 down-regulated genes. RANBP2-like and ribosomal protein L13 were the most up-regulated and down-regulated genes in KFD patients, respectively. The altered gene expression involved in the human immune system, chromatin remodeling, and gene transcription. A comparison of KFD and healthy datasets of exomes and transcriptomes may allow further insights into the KFD phenotype. The results may also facilitate future KFD diagnosis and treatment.

Kikuchi-Fujimoto disease presenting in a patient with SARS-CoV-2: a case report.

BACKGROUND: We present a yet to be described association of SARS-CoV-2 infection with Kikuchi-Fujimoto disease. CASE PRESENTATION: A 32-year-old physician with history of SARS-CoV-2 infection presented to the emergency department with 2 weeks of fever, chills, and right sided cervical lymphadenopathy. He was treated empirically for presumed folliculitis with worsening of symptoms leading to repeat presentation to the emergency department. Extensive workup was unrevealing of an infectious cause and needle biopsy of the lesion was unrevealing. An excisional lymph node biopsy revealed follicular hyperplasia with necrotic foci showing abundance of histiocytes at the edge of necrosis with CD8 predominance of T-cells. Final diagnosis was deemed to be Kikuchi-Fujimoto disease. Antibiotic therapy was discontinued, and the patient's symptoms resolved with steroid therapy and expectant management. CONCLUSIONS: This is the first report of a patient developing Kikuchi-Fujimoto disease following SARS-CoV-2 infection. Clinicians should be aware of Kikuchi-Fujimoto disease as a possibility when approaching patients with hyper-inflammatory states who present with cervical lymphadenopathy.

Characterization of Plasmacytoid Dendritic Cells, Microbial Sequences, and Identification of a Candidate Public T-Cell Clone in Kikuchi-Fujimoto Disease.

OBJECTIVES: Kikuchi-Fujimoto disease (KFD) is a self-limited lymphadenitis of unclear etiology. We aimed to further characterize this disease in pediatric patients, including evaluation of the CD123 immunohistochemical (IHC) staining and investigation of potential immunologic and infectious causes. METHODS: Seventeen KFD cases and 12 controls were retrospectively identified, and the histologic and clinical features were evaluated. CD123 IHC staining was quantified by digital image analysis. Next generation sequencing was employed for comparative microbial analysis via RNAseq (5 KFD cases) and to evaluate the immune repertoire (9 KFD cases). RESULTS: In cases of lymphadenitis with necrosis, >0.85% CD123+ cells by IHC was found to be six times more likely in cases with a final diagnosis of KFD (sensitivity 75%, specificity 87.5%). RNAseq based comparative microbial analysis did not detect novel or known pathogen sequences in KFD. A shared complementarity determining region 3 (CDR3) sequence and use of the same T-cell receptor beta variable region family was identified in KFD LNs but not controls, and was not identified in available databases. CONCLUSIONS: Digital quantification of CD123 IHC can distinguish KFD from other necrotizing lymphadenitides. The presence of a unique shared CDR3 sequence suggests that a shared antigen underlies KFD pathogenesis.

Kikuchi-Fujimoto Disease With Unusual Cutaneous Findings.

ABSTRACT: We present a case of the rare Kikuchi-Fujimoto disease (KFD) in a 14-year-old patient admitted to UCLA Medical Center with fever, weight loss, and pancytopenia. Physical examination revealed tender subcutaneous nodules and cervical lymphadenopathy. A lymph node biopsy showed findings consistent with KFD. The skin biopsy showed mild superficial dermal edema with neutrophil-predominant inflammation. In addition, rare atypical monocytoid cells were seen. This histologic finding of a Sweet-like morphology has not been reported previously in the literature in association with KFD. The differential diagnosis included Sweet syndrome arising in association with KFD, underlying connective tissue, and an infectious etiology.

Kikuchi-Fujimoto Disease Triggered by Systemic Lupus Erythematosus and Mycoplasma pneumoniae Infection-A Report of a Case and a Review of the Literature.

ABSTRACT: Kikuchi-Fujimoto disease (KFD) is a necrotizing histiocytic lymphadenitis that was described for the first time in 1972 in Japan. Its etiology is still not fully understood. It has been reported in association with many different agents, diseases, and triggering factors without any conclusive result. To the best of our knowledge, we report for the first time a case of KFD with systemic lupus erythematosus in a child in association with a polymerase chain reaction (PCR)-positive throat swab for Mycoplasma pneumoniae. Although difficult to prove, the acute M. pneumoniae infection might have served as a triggering event for the development of KFD in our case. We encourage further studies to investigate a potential relationship between KFD and M. pneumoniae, which should also use PCR-based testing for this pathogen in patients with KFD.

Kikuchi disease as a possible cause of ischaemic stroke: a case report.

INTRODUCTION: Kikuchi disease (KFD) is a rare and self-limiting benign disease which usually occurs in young women. The difference between our case and the previous case is that the initial symptom of this case is transient ischemic attack (TIA). METHODS: A 46-year-old female patient presented at the clinic with a 2-week history of paroxysmal left limb weakness and fever. Imaging examinations showed the multiple lymph nodes in neck enlarged bilaterally. Finally, we arranged a lymph node biopsy for the patient. RESULTS: The resulted of lymph node biopsy showed the disorder of lymph node structures, widespread histiocytic infiltration and cell nucleus fragments, suggesting KFD. CONCLUSION: TIA as a complication of KFD has never been reported in the previous literature, which provided a new direction for diagnosis of TIA and suggested that KFD may be a rare cause of ischemic stroke.

Necrotizing lymphadenitis : A case report and literature review.

BACKGROUND: Necrotizing lymphadenitis is a rare disease. It is often misdiagnosed because of the lack of typical clinical manifestations. It is worth noting that necrotizing lymphadenitis may be a precursor lesion of systemic lupus erythematosus or tumours, so regular follow-up is needed to facilitate early diagnosis. Here, we report a case and conduct a literature analysis summarizing the clinical features of necrotizing lymphadenitis and its treatment and management practices. CASE PRESENTATION: A 16-year-old young woman presented with fever and lymphadenopathy as the main clinical manifestations, accompanied by a rash during fever that disappeared as the fever subsided. After completing imaging and laboratory examinations, we excluded other diseases such as infections, autoimmune diseases, and malignant tumours. Finally, we diagnosed the patient with necrotizing lymphadenitis based on the results of lymph node biopsy. The symptoms of the patient improved after glucocorticoid treatment, and she was followed up for half a year without recurrence of symptoms. CONCLUSION: In the clinic, young women with fever and lymphadenopathy as major symptoms should be screened for necrotizing lymphadenitis to facilitate early diagnosis and treatment. Although necrotizing lymphadenitis is self-limiting, its clinical manifestations are similar to those of many diseases. Therefore, it is easily misdiagnosed. An in-depth understanding of the disease is conducive to early diagnosis and treatment in the clinic, thereby reducing further damage to the body and reducing unnecessary evaluation and treatment.