Cat-scratch disease: a rare cause of osteomyelitis.

Cat-scratch disease is a zoonosis caused by Bartonella henselae, characterised by regional lymphadenopathy. Rarer presentations, such as osteomyelitis, can occur.We present an adolescent girl with severe right lumbar pain and fever, without animal contacts or recent travels. On examination, pain on flexion of torso, movement limitation and marked lordosis were noted, but there were no inflammatory signs, palpable masses or lymph nodes. Serological investigations revealed elevated inflammatory markers. Imaging revealed a paravertebral abscess with bone erosion. Several microbiological agents were ruled out. After a second CT-guided biopsy, PCR for Bartonella spp was positive. At this point, the family recalled having a young cat some time before. Cat-scratch disease was diagnosed, and complete recovery achieved after treatment with doxycycline and rifampicin.Cat-scratch disease is a challenging diagnosis in the absence of typical features. However, B. henselae must be investigated if common pathogens are ruled out and response to therapy is poor.

Bartonella henselae Infection and Lymphadenopathy in a Patient With T Cell Acute Lymphoblastic Leukemia.

Patients undergoing therapy for T cell acute lymphoblastic leukemia are at risk of infections during their treatment course. Cat scratch disease caused by Bartonella hensalae can masquerade as leukemic relapse and cause systemic infection. Obtaining a thorough exposure history may aid clinicians in making the diagnosis.

Variantes en la presentación clínica de la enfermedad por arañazo de gato en niños del hospital Garrahan / Variants in the clinical presentation of cat scratch disease in children at Garrahan Hospital

La infección por Bartonella henselae (BH) adopta diversas formas de presentación clínica en pediatría. Según la bibliografía la forma de presentación más frecuente en pacientes inmunocompetentes es la linfadenopatía única asociada a fiebre. En el 85 % de los casos se compromete un solo ganglio siendo los axilares y los epitrocleares los más frecuentemente involucrados. Existen otras formas de presentación menos frecuentes que debemos tener en consideración, para poder realizar un diagnóstico precoz e indicar un tratamiento adecuado si así lo requiere. El diagnóstico requiere de la sospecha clínica del equipo de salud tratante, junto al antecedente epidemiológico, los hallazgos clínicos del examen físico y la realización de serologías que incluyan el dosaje de inmunoglobulina M y G. Los objetivos del presente trabajo fueron reconocer las manifestaciones clínicas típicas y atípicas de la EAG por Bartonella henselae, describir la epidemiología, características clínicas y evolución de esta enfermedad que se presentaron en nuestro hospital. Se estudiaron un total de 187 pacientes. La media de edad fue de 7.6 años (rango 1-14); siendo 53.5% de género masculino. Las formas de presentación más frecuentes en nuestro trabajo fueron la adenitis y la fiebre. La mayoría recibió diversos esquemas de tratamiento antibiótico, secundario al retraso en el diagnóstico. La tasa de hospitalización fue muy baja, remitió con tratamiento ambulatorio con antibióticos o sin ellos (AU)

Bartonella henselae infection has different clinical presentations in pediatrics. According to the literature, the most common form of presentation in immunocompetent patients is single lymphadenopathy associated with fever. In 85 % of the cases a single lymph node is involved, with the axillary and epitrochlear nodes being the most commonly involved. There are other, less frequent, forms of presentation that should be taken into consideration in order to make an early diagnosis and indicate appropriate treatment if required. Diagnosis relies on clinical suspicion by the treating healthcare team, together with the epidemiological history, clinical findings on physical examination, and serology including immunoglobulin M and G dosage. The objectives of this study were to identify both the typical and atypical clinical manifestations of Bartonella henselae cat scratch disease, to describe the epidemiology, clinical characteristics, and outcomes of cases presenting at our hospital. A total of 187 patients were studied. The mean age was 7.6 years (range 1-14); 53.5% were male. The most frequent forms of presentation in our study were adenitis and fever. Most of them received different antibiotic treatment regimens due to delayed diagnosis. The hospitalization rate was very low and the disease typically resolved with outpatient treatment, with or without antibiotics (AU)

A Case of Culture-Negative Endocarditis Due to Bartonella henselae and Cat Scratch Disease.

This report describes the case of a 73-year-old female with a history of a prosthetic mitral valve and breast cancer who presented with fever and confusion. Brain imaging revealed multiple ischemic infarcts, and abdominal imaging demonstrated splenic infarcts. Workup with transesophageal echocardiogram revealed a vegetation on the aortic valve, but several blood cultures had no bacterial growth. Further history revealed a recent exposure to a stray cat, and the patient was found to have positive antibodies for Bartonella henselae, the organism implicated in cat scratch disease. She was treated with the appropriate course of antibiotics, and she made a full recovery to her baseline functional status. This report emphasizes the importance of a comprehensive patient history and a broad differential diagnosis.

[Two patients with cat scratch disease]. / Twee patiënten met kattenkrabziekte.

BACKGROUND: Cat scratch disease (CSD) is caused by Bartonella henselae infection. CSD is usually characterized by self-limiting regional lymphadenopathy. However, sometimes CSD presents as a disseminated disease with multiple organ involvement. CASE DESCRIPTIONS: We describe two patients with CSD. Patient A, an 18-year old woman, was referred because of fatigue, a subfebrile temperature and axillary lymphadenopathy. Patient B, a 50-year old man, visited the emergency ward with fever, back pain and painful inguinal lymphadenopathy. MRI showed osteitis of vertebrae and hepatic abcesses. In both patients symptoms started after being scratched by a cat and both were tested positive for infection with Bartonella henselae. Patient B was treated with antibiotics. Both patients made a full recovery. CONCLUSION: Recent contact with a cat in a patient with unexplained fever and lymphadenopathy raises the possibility of CSD. Diagnosis can be confirmed by serologic testing, histopathology or PCR. Antimicrobial treatment must be considered in all cases.

[A rare case of hepatosplenic cat scratch disease].

A female patient in her 60s, treated with oral corticosteroids for scleroderma diagnosed 11 years ago, visited our hospital complaining of a persistent fever and liver dysfunction. She was treated with antibiotics, but her fever continued. Abdominal ultrasonography revealed multiple hypoechoic splenic masses. Splenic masses revealed multiple masses with no contrast effect in arterial and portal phases and nuclear in equilibrium phase by contrast computed tomography study, as well as hyperintensity masses with low signal areas in magnetic resonance imaging T2-weighted images. Liver tissue was obtained by percutaneous liver biopsy, and histological findings showed epithelioid cell granulomas without tumor cells. Further interview and physical examination revealed scratch scars from domestic cats and left axillary lymph node swelling. Hence, a cat scratch disease was suspected. She was diagnosed with cat scratch disease by serum indirect immunofluorescence. Her fever was resolved with minocycline administration. Therefore, persistent fever with splenic masses should be suspected of hepatosplenic cat scratch disease.

A case report of diagnosis of cat-scratch disease using metagenomic next-generation sequencing.

Cat-scratch disease (CSD) is an anthropozoonotic infection caused by Bartonella henselae, and it is one of the most common causes of lymph node infections in children and adolescents. B. henselae, belonging to the genus Bartonella, is a common human pathogen of human beings. CSD commonly develops as a result of cat scratches and bites or when injured skin comes into contact with cat saliva. The manifestation of CSD clinically differs for each patient based on their immune system. Individuals who have healthy immune systems generally manifest minimal clinical symptoms and do not necessitate any form of treatment. However, patients who have hypo-immunity require prompt medical attention due to the potential manifestation of severe symptoms that affect multiple systems of the body. Long latency and atypical clinical manifestations are characteristics of CSD. Bartonella isolation and identification are challenging procedures that require specialized equipment. There is no gold standard method for CSD diagnosis, and misdiagnosis and missed diagnosis rates are typically high. We present the case of a middle-aged male patient who developed fever, chills, anal distension, dizziness, and muscle pain for 10 days. The patient had a documented history of cat bites 1 month prior to the onset of symptoms. Following admission, he underwent an examination to determine superficial lymphadenopathy and hypoimmunity. Additionally, he had a fever during the disease. As the patient refused a needle biopsy of lymph nodes, metagenomic next-generation sequencing (mNGS) was employed and B. henselae was detected in the peripheral blood. The patient was diagnosed with CSD and treated with a combination of azithromycin and doxycycline. The fever symptoms were alleviated, and the patient was ultimately discharged. As a result of this case, we suggest that mNGS be used as a crucial supplementary diagnostic tool for individuals with compromised immune systems who may have CSD, especially when conventional diagnostic methods are inconclusive.

Clinical utility of whole body diffusion-weighted imaging in an immunocompetent adult with atypical cat scratch disease.

BACKGROUND: Cat scratch disease (CSD) is an infectious disease caused by Bartonella henselae. CSD follows a typical course, characterized by regional lymphadenopathy. In atypical CSD, the lesions spread to systemic organs and can cause fever of unknown origin (FUO). A previous study showed the usefulness of whole-body magnetic resonance imaging (WB-MRI) with diffusion-weighted imaging (DWI) for limited areas in the diagnosis of FUO, but there are no studies on the clinical utility of whole-body DWI (WB-DWI). We herein report the case of an immunocompetent young man in whom contrast-enhanced CT-unidentifiable multiple liver abscess and osteomyelitis were successfully detected by WB-DWI. Follow-up with a liver biopsy helped confirm an atypical CSD diagnosis. CASE PRESENTATION: A 23-year-old previously healthy man was admitted for a 19-day history of high fever despite 3-day treatment by azithromycin. His physical examination was unremarkable and contrast-enhanced CT showed only a low attenuated area in the right lobe of the liver, indicating a cyst. WB-DWI revealed multiple nodular lesions of hypo-diffusion in the liver, spine, and pelvic region. The biopsy specimens of the liver abscess showed no evidence of tuberculosis/malignancy and the polymerase chain reaction (PCR) test of liver abscess aspirate showed positive findings for Bartonellahenselae, confirming the diagnosis of CSD. He completed minocycline monotherapy for a total of 60 days without any deterioration. CONCLUSIONS: WB-DWI can be useful for the diagnosis of atypical CSD with hepatic and bone involvement, which can cause FUO in young immunocompetent adults.

Severe Bartonella henselae bone infection in a kidney transplanted young man.

We present a case of a young kidney transplanted man. He was admitted with lymphadenopathy, fluctuating fever and night sweats 2 months after a cat bite. After admission, he developed severe pain around his right hip. An 18F-fluorodeoxyglucose (FDG)-positron emission tomography/CT revealed intense FDG-uptake in lymph nodes, spleen and bone, suggestive of lymphoma. An extracted lymph node showed confluent granulomas, microabscesses with neutrophils and scattered multinucleated giant cells histologically. The patient had history of latent tuberculosis and proteinase 3 -anti-neutrophil cytoplasmic antibodies associated (PR3-ANCA) vasculitis, making differential diagnostic considerations complicated. Bartonella henselae antibodies was detected in blood and B. henselae DNA in a lymph node. He was started on doxycycline and rifampicin. Due to severe drug interactions with both tacrolimus and increasing morphine doses, rifampicin was changed to azithromycin. He received 12 days of relevant antibiotic treatment and responded well. He was discharged after 16 days with close follow-up and was still in habitual condition 12 months later.

Treatment of a cat with presumed Bartonella henselae-associated immune-mediated hemolytic anemia, fever, and lymphadenitis.

A 2.5-year-old castrated male cat presented with fever and marked generalized lymphadenopathy of 4-months duration, despite treatment with amoxicillin-clavulanate/marbofloxacin. Abnormalities were not detected on complete blood count, serum chemistry, and FIV/FeLV test apart from a borderline, non-regenerative anemia. Peripheral lymph node fine needle aspirations revealed a marked increase in the percentage of intermediate- and lymphoblastic-lymphocytes in addition to reactive macrophages. Three weeks after presentation, the cat developed a severe, regenerative, immune-mediated hemolytic anemia (IMHA) which responded to immunosuppressive therapy. Fever and lymphadenopathy persisted. Peripheral lymph nodes tested positive for Bartonella henselae DNA in real-time PCR assay and sequencing. Treatment with pradofloxacin and doxycycline resulted in resolution of clinical signs, and negative PCR tests. Despite its reported low pathogenicity, B. henselae infection should also be considered in cats with protracted unexplained fever, lymphadenitis, and IMHA. Furthermore, a combination of pradofloxacin and doxycycline might be considered in cats with bartonellosis given its apparent clinical efficacy.

Miositis por Bartonella henselae: caso clínico en una adolescente / Bartonella henselae myositis: case report in an adolescent

La miositis de origen vírico o bacteriano es frecuente en la edad pediátrica. Causa dolor muscular y debilidad, con fiebre y malestar general. Una causa es la infección por Bartonella henselae, bacteria implicada en la enfermedad por arañazo de gato que, a veces, causa afectación multisistémica. Se presenta el caso de una adolescente que acudió al servicio de urgencias por mialgia intensa, malestar, adelgazamiento y esplenomegalia. En el labortorio se observaron parámetros inflamatorios elevados. Refería contacto con un gato. Entre los estudios realizados, la resonancia magnética (RM) de miembros inferiores mostró una imagen compatible con miositis inflamatoria bilateral. En la RM abdominal, se observaron tres lesiones esplénicas no detectadas previamente y el fondo de ojo mostraba una lesión compatible con oclusión arterial retiniana o vasculitis. Se indicó tratamiento antibiótico por vía intravenosa durante 21 días con cefotaxima y cloxacilina, tras los cuales desaparecieron los signos y síntomas, aunque los reactantes inflamatorios persistieron elevados. Con base en el cuadro clínico (miositis + coriorretinitis + absceso esplénico) se pensó en una posible infección por B. henselae y se inició tratamiento oral con azitromicina y rifampicina durante 14 días. Luego del tratamiento, los valores de laboratorio fueron normales, así como la RM de control, y se constató una IgG positiva para la bacteria

Infectious myositis, whether viral or bacterial, is frequent in pediatric age. It causes muscle pain and weakness, associated with fever and general malaise. One cause is Bartonella henselae, responsible for cat scratch disease, which sometimes causes systemic symptoms. We report the case of an adolescent who came to the emergency room with intense myalgia, malaise, weight loss and splenomegaly. Blood tests showed high inflammatory markers. She had been in touch with a cat. Studies were carried out including: lower limbs MRI suggestive of bilateral inflammatory myositis, abdominal MRI with three previously undetected splenic lesions and dilated fundus examination that showed possible retinal arterial occlusion or vasculitis. After 21 days of intravenous antibiotic therapy (cefotaxime + cloxaciline), she became asymptomatic, but inflammatory markers remained high. Suspecting Bartonella henselaeinfection (myositis + chorioretinitis + splenic abscess), oral azithromycin and rifampicin were prescribed for 14 days. Blood tests and control MRI became normal, and IgG was positive.

Concurrence of cat-scratch disease and paradoxical tuberculosis-IRIS lymphadenopathy: a case report.

BACKGROUND: Mycobacterial infections can cause significant morbidity when cellular immunity is compromised. Patients with AIDS can be affected directly from infection or through mycobacterial IRIS, especially if they are previously untreated for HIV. Herein a case of tuberculous lymphadenitis is reported, which primarily responded to antimicrobials but complicated by IRIS and cat-scratch disease at a later course. CASE PRESENTATION: A 23-year-old man, intravenous drug user with untreated HIV and HCV infection presented with fever and painful cervical lymphadenopathy. Mycobacterium tuberculosis was isolated from PCR and culture of ultrasound-guided lymph node aspirate and a four-drug anti-TB regimen was subsequently administered, leading to complete resolution of clinical and laboratory abnormalities. Given the patient's CD4 count (67 cells per mm3), antiretroviral treatment started seven weeks after TB treatment initiation. Within the first month of ART fever recurred along with cervical lymph node inflammation. Paradoxical IRIS was considered as the most probable diagnosis but workup expanded, revealing acute Bartonella infection. A posteriori, the patient remembered being scratched by a stray cat two weeks before his new symptoms started. Doxycycline and corticosteroid monotherapy failed to resolve symptoms, whereas a combination of doxycycline for 3 months and methylprednisolone with long-term tapering led to negative follow-up Bartonella antibodies and complete clinical and biochemical response, without recurrence. CONCLUSIONS: Co-infection with TB and Bartonella presenting with lymphadenitis is unusual. Cat-scratch disease can be a rare clinical presentation of Bartonella infection in patients with AIDS, but coexistence of bartonellosis and paradoxical IRIS has never been reported before. However, physicians treating people living with HIV should be aware of this potential concurrence. Early testing for Bartonella infection could be offered in patients with TB and HIV co-infection in case of acute deterioration or partial response to treatment, especially if they have a history of cat exposure, since clinical picture can be indistinguishable.

Uncommon aetiology of lymphadenopathy in a healthy child: a sporotrichosis case with painless lymphadenopathy.

A 6-year-old boy was referred to the paediatric infectious disease clinic with a 2-month history of enlarged, erythematous, painless cervical lymph nodes. He initially presented to his paediatrician with a painless lesion. At that time, he was treated empirically with clindamycin and azithromycin due to a history of cat exposure. Despite treatment, the lesion evolved into a non-healing linear ulcer with painless, ascending cervical lymphadenopathy. Serologies were negative for Bartonella henselae antibodies. Additional laboratory studies revealed eosinophilia and negative Toxoplasma gondii antibodies. After no improvement following a course of trimethoprim-sulfamethoxazole, further questioning revealed that the patient had fallen into a haystack 1 month before the initial cervical lesion. The patient's parents opted to treat the infection empirically for sporotrichosis with itraconazole rather than undergo lymph node biopsy. At the 2-week follow-up, his lymphadenopathy had resolved and had returned to baseline activity.

Cat-Scratch Lymphadenitis Presenting with Right Upper Arm and Axillary Masses: a Case Report Mimicking Lymphoma and Potential Diagnostic Pitfall.

Background: Cat scratch disease (CSD) is an infectious disease caused by a cat's scratch, hard enough to break the skin's surface. Clinical manifestations include inflammatory lymphadenopathy and papular lesions at the site of the injury. However, it may be mistaken for a neoplasm-related process e.g., lymphoma due to its similar clinical presentation. Objective: To report a CSD case in an Indonesian male presenting with mass-like symptoms in the oncologic ward of our center. Case report: A 24-year-old male presented with painful and swelling masses in the right upper arm and right armpit for the last 4 months, enlarged progressively, and feverish for two days. Our initial differential diagnosis was lymphoma by history and routine physical examination, however. The patient reported a history of sleeping with his cat and recently experiencing a cat bite. We conducted the ultrasonography and lymph node biopsy to establish the final diagnosis and it was revealed to be related to CSD. The patient was treated with lymphadenectomy and azithromycin 500 mg bd for 7 days. The patient was completely treated with no additional complaints after two weeks of follow-up. Conclusion: The differential diagnosis for CSD is relatively broad, including active infection, an ongoing inflammatory process, or a metastatic process; hence, thorough diagnostic approaches should be made in approaching CSD cases to avoid the pitfall or mistreatment in advance.

Clinical challenge - scratching the surface of the sheath.

A 63-year-old Caucasian man with hypertension, hyperlipidemia, adrenal insufficiency, and history of metastatic spindle cell melanoma previously treated with ipilimumab, presented with unilateral papillitis in the left eye. The disc edema evolved to neuroretinitis with additional MRI findings of perineuritis. Broad laboratory evaluation confirmed active B. henselae infection, and he confirmed exposure to a newly adopted kitten. His vision improved following a course of antibiotics and oral steroids with resolution of clinical findings. To the best of our knowledge, this is the first reported case of cat-scratch neuroretinitis with MRI findings of optic nerve and optic nerve sheath enhancement.

Cat scratch disease in a 23-year-old male-Case report.

Cat-scratch disease (CSD) is an infectious disease that usually presents with fever, headache, loss of appetite, weight loss, tender lymphadenopathy, and other symptoms. CSD is also the most common cause of infectious lymphadenitis in children, adolescents, and young adults. This contagious disease most often results from a scratch or bite of a cat. The course of this disease depends on the patient's immune status. CSD sometimes presents as a systemic disease and leads to various disease entities. In this study, we describe the case of a 23-year-old man exhibiting fever, generalized weakness, and neck swelling. The patient was unconscious when presented to the Emergency Department. He was given at least 3-4 liters IV bolus of 0.9% normal saline, but it failed to raise the blood pressure. He was then given an inotropic drug (noradrenaline) for low blood pressure and antibiotics (azithromycin) for fever. Venereal disease research laboratory (VDRL) and human immunodeficiency virus (HIV) serology came out negative. Histopathology ruled out tuberculosis and malignancy and confirmed necrotizing/suppurative granulomatous inflammation. These features favor the diagnosis of CSD.

Bartonella henselae masquerading as possible gamma-delta T-cell lymphoma in a paediatric patient with 22q11.2 deletion syndrome.

A 14-year-old boy with 22q11.2 deletion syndrome and a right ventricular to pulmonary artery xenograft conduit presented to an Australian tertiary children's hospital with prolonged fevers, weight loss, splenomegaly and a high proportion of gamma-delta T cells in peripheral blood and bone marrow, concerning for possible gamma-delta T-cell lymphoma. However, investigations did not reveal evidence of lymphoma or autoimmune disease. After 5 months of intermittent fever episodes and ongoing symptoms, he was found to have an extremely high Bartonella henselae titre (8192) on serological testing, with the organism also detected on blood PCR. After 6 months of oral azithromycin and rifampicin, with complete resolution of his symptoms 3 months into treatment, his blood PCR was negative and gamma-delta T cells in peripheral blood were decreasing. The B. henselae titre remained unchanged for some time, but decreased to 2048 around 1 year after treatment was started.

A pediatric case of Bartonella henselae and Epstein Barr virus disease with bone and hepatosplenic involvement.

Background: Cat scratch disease (CSD) is an infectious disorder caused by Bartonella henselae. The infection usually presents as local lymphadenopathy, fever, and mild constitutional symptoms. Systemic or severe disease is reported in 5-20% of patients with CSD. We report a case of disseminated CSD with osteomyelitis and hepatosplenic disease and a review of the literature. Case report: A previously healthy 5-year-old male presented with prolonged fever and abdominal pain, followed by low back pain. The serologic test showed positive IgG for B. henselae and IgM and IgG for Epstein Barr virus (EBV). The abdominal ultrasound showed hepatic and splenic hypoechoic lesions, and the magnetic resonance imaging (MRI) revealed spondylitis of the D6 vertebra. He received treatment with azithromycin for 4 weeks and rifampicin for 6 weeks. The symptoms disappeared, and the abdominal ultrasound was normal nine months later. Conclusions: Disseminated CSD is infrequent. The diagnosis requires a high rate of suspicion. Laboratory findings of Bartonella infection are often non-specific. Serologic test, polymerase chain reaction of B. henselae in blood or biopsied material of the site of involvement and imaging test can be performed to confirm the diagnosis. The diagnosis of disseminated B. henselae was based on significantly elevated blood titers, radiologic findings, and epidemiologic history. Treatment of CSD depends on the disease presentation. Azithromycin is used as a first-line agent for lymphadenopathy. The optimum treatment and its duration have not been established in atypical or complicated CSD, including patients with osteomyelitis and hepatosplenic disease.

Introducción: La enfermedad por arañazo de gato (EAG) es una patología infecciosa originada por Bartonella henselae. Habitualmente se presenta como linfadenopatía local, fiebre y síntomas constitucionales leves. El 5-20% de los pacientes con EAG manifiestan una afectación sistémica. Se presenta un caso de EAG diseminada, con osteomielitis y enfermedad hepatoesplénica, y se hace una revisión de la literatura sobre la EAG. Caso clínico: Paciente de sexo masculino de 5 años, previamente sano, que presentó fiebre prolongada y dolor abdominal, seguidos de dolor en la parte baja de la espalda. En la serología, presencia de IgG frente a B. henselae y de IgM e IgG frente al virus de Epstein-Barr. En la ecografía abdominal se observaron lesiones hipoecoicas en el hígado y el bazo, y la resonancia magnética mostró espondilitis de D6. Recibió tratamiento con azitromicina 4 semanas y rifampicina 6 semanas. Los síntomas desaparecieron y la ecografía abdominal a los 9 meses fue normal. Conclusiones: La EAG diseminada es infrecuente. El diagnóstico requiere un alto grado de sospecha. Los hallazgos de laboratorio en la infección por Bartonella suelen ser poco específicos. Para confirmar el diagnóstico pueden hacerse serología, reacción en cadena de la polimerasa para B. henselae en sangre o en biopsia de tejidos afectados, y estudios de imagen. El diagnóstico de EAG diseminada se basa en títulos elevados en la sangre, hallazgos radiológicos e historia epidemiológica. El tratamiento depende de la forma de presentación. En los casos de linfadenopatía se utiliza azitromicina. En la EAG atípica o complicada, que incluye osteomielitis y afectación hepatoesplénica, no están bien establecidos el tratamiento ni su duración.

Cat at home? Cat scratch disease with atypical presentations and aggressive radiological findings mimicking sarcoma, a potential diagnostic pitfall.

Background and purpose - Cat scratch disease (CSD) is a self-limiting disease caused by Bartonella (B.) henselae. It is characterized by granulomatous infection, most frequently involving lymph nodes. However, it can present with atypical symptoms including musculoskeletal manifestations, posing a diagnostic challenge. We describe the prevalence and demographics of CSD cases referred to a sarcoma center, and describe the radiological, histological, and molecular findings.Patients and methods - Our cohort comprised 10 patients, median age 27 years (12-74) with clinical and radiological findings suspicious of sarcoma.Results - 7 cases involved the upper extremities, and 1 case each involved the axilla, groin, and knee. B. henselae was found in 6 cases tested using polymerase chain reaction and serology in 5 cases. 9 cases were soft tissue lesions and 1 lesion involved the bone. 1 patient had concomitant CSD with melanoma metastasis in enlarged axillary lymph nodes. On MRI, 5 soft tissue lesions were categorized as probably inflammatory. In 3 cases, with still detectable lymph node structure and absent or initial liquefaction, the differential diagnosis included lymph node metastasis. A sarcoma diagnosis was suggested in 4 cases. The MRI imaging features of the bone lesion were suspicious of a bone tumor or osteomyelitis.Interpretation - Atypical imaging findings cause a diagnostic challenge and the differential diagnosis includes malignant neoplasms (such as sarcoma or carcinoma metastasis) and other infections. The distinction between these possibilities is crucial for treatment and prognosis.