Confirmation of Diagnosis of Cat Scratch Disease by Immunohistochemistry

Non-neoplastic histiocytic and dendritic cell disorders in lymph nodes

Benign and malignant proliferations of histiocytes and dendritic cells may be encountered in lymph nodes. Reactive histiocytic and dendritic cell infiltrates occur in response to diverse stimuli and in addition to causing lymphadenopathy, may be present unexpectedly in lymph nodes excised for other indications. This review summarizes the pathogenesis and histopathological features of the various non-neoplastic histiocytic and dendritic cell infiltrates that can occur in lymph nodes.

Disseminated cat-scratch disease: case report and review of the literature

Cat scratch disease (CSD) can present as a systemic disease in 5-10% of cases and lead to various disease entities. A previously healthy 16-month-old boy presented with fever for 7 days without other obvious symptoms. Abdominal computed tomography scan demonstrated enlarged right inguinal lymph nodes and multiple small round hypodensities in the spleen. Despite antibiotic treatment for 1 week, the fever persisted and the intrasplenic lesions progressed. Inguinal lymph node biopsy confirmed CSD by immunohistochemistry staining. The diagnosis of CSD was also supported by a history of contact, imaging and serological findings. The patient recovered after treatment with azithromycin for a total of 5 weeks and, in serial follow-up, the hepatosplenic micro-abscesses resolved after 4th months.

Immunohistochemistry in the diagnosis of cutaneous bacterial infections

The identification of pathogens is of vital importance for the adequate treatment of infections. During the past 2 decades, the approach to histopathologic diagnosis has been dramatically transformed by immunohistochemistry (IHC) specifically in the diagnosis and classification of tumors and more recently in the diagnosis of infectious diseases in tissue samples. The main goals of this article were to: (1) identify by IHC the cutaneous structures where bacterial pathogens are expressed in the course of infection, (2) identify the specific cells in which bacterial pathogens are expressed in positive cases, and (3) describe the pattern of distribution of the bacterial antigens within these cells (nuclear, cytoplasmatic, or membranous). This article is an up-to-date overview of the potential uses and limitations of IHC in the histopathologic diagnosis of cutaneous bacterial infections. In conclusion, IHC is especially useful in the identification of microorganisms that are present in low numbers, stain poorly, are fastidious to grow, culture is not possible, or exhibit an atypical morphology.

Epithelioid cell granulomatous response of Waldeyer's ring among Japanese : a clinicopathological and immunohistochemical study of 16 cases

The tonsils are uncommonly affected by granulomatous inflammation. This study attempted to clarify the clinicopathological and immunohistochemical findings and presence or absence of Epstein-Barr virus (EBV) in tonsilar granulomatous inflammation. A total of 537 consecutive specimens from tonsillectomies performed at Dokkyo University School of Medicine between 1999 and March 2012 were reexamined. Using formalin-fixed, paraffin-embedded sections, histological, immunohistochemical, and in situ hybridization (ISH) studies were performed. Epithelioid granulomas (EPGs) were identified in the tonsils in 16 (3.0%) cases. There were 8 males and 8 females, aged 4 to 57 years (mean, 23). In 11 patients, EPGs were located in the germinal center (GC), whereas they were located in the interfollicular area as well as GC in the remaining 5 cases. Three types of EPG have been delineated : (i) poorly demarcated small epithelioid cell granulomas (n = 6) ; (ii) well-demarcated non-caseating sarcoid-like granulomas (n = 5) ; and (iii) EPGs within GC showing suppurations at the center (n = 5). An ISH study demonstrated EBV-encoded small RNA (EBER)(+) cells in 4 lesions. The present study demonstrated that the majority of EPGs were located in the GC and tonsilar EPGs showed histological variation.

Evaluation of immunohistochemistry in identifying Bartonella henselae in cat-scratch disease

Cat-scratch disease (CSD) is largely due to infection with Bartonella henselae. Microbiologic detection is difficult, and molecular testing is not readily available. A monoclonal antibody (mAB) to B henselae has become commercially available. We evaluated the usefulness of immunohistochemical analysis (IHC) for diagnosing CSD on surgical specimens and compared these results with polymerase chain reaction (PCR) detection and serologic testing for B henselae. We studied 24 formalin-fixed, paraffin-embedded (FFPE) cases of lymphadenitis with histologic and/or clinical suspicion of CSD. Control cases included 14 cases of lymphadenopathy other than CSD. FFPE tissue sections were evaluated with an mAB to B henselae, Steiner silver stain (SSS), and PCR that targeted B henselae and Bartonella quintana. Positive cases were as follows: SSS, 11 (46%); PCR, 9 (38%); and IHC, 6 (25%). Only 2 cases (8%) were positive for all 3 studies. All control cases were negative for IHC and PCR. The diagnostic sensitivity of these 3 tests is low for CSD. SSS seems to be the most sensitive test but is the least specific. PCR is more sensitive than IHC and may, therefore, serve as a helpful second-line test on all IHC- cases.

Adult systemic cat scratch disease associated with therapy for hepatitis C

Background

We describe the first case of systemic cat scratch disease in a patient receiving peginterferon α-2a and ribavirin for treatment of hepatitis C. Cases of adult systemic CSD are extremely infrequent and immunomodulatory treatment for hepatitis C has been associated with aberrant host responses to common pathogens.

Case presentation

A 52 year old man being treated for hepatitis C presented with diffuse lymphadenopathy, weight loss, fevers and splenic lesions. Symptoms were initially confused with adverse effects of his regimen, delaying recognition of his infection. Diagnostic investigation, including histopathology, microbiology and serologic parameters, confirmed that his illness was due to disseminated cat scratch disease with Bartonella henselae.

Conclusion

Disseminated CSD is exceptionally rare in adults. We describe the first case of disseminated cat scratch disease associated with peginterferon α and ribavirin to alert clinicians of the need to be aware of unusual manifestations of common infections in this population.