Cat scratch disease. An epidemiological and ultrastructural study of lymphadenitis caused by Warthin-Starry positive bacteria

Emergent opportunities in humans: playful kittens, an arthropod vector, and a zoonotic agent

Bartonella henselae is implicated as the main etiologic agent of Cat scratch disease (CSD, Cat-scratch fever). A majority of domestic cats may harbor the intra-erythrocytic agent for extended periods without apparent disease. In humans, B. henselae most commonly results in a subacute, bacterial infection that presents with one or more reddish papules which may progress to pustules and regional lymph node enlargement. Usual features include fever, malaise, and a granulomatous lymphadenitis on biopsy. However, atypical clinical presentations occur, albeit with infrequence, and may result in a difficult and protracted diagnostic process. The infection in susceptible hosts such as immunocompromised or elderly patients may result in endocarditis, encephalitis, fever of unknown origin, and general malaise. It is not transmitted from person to person and quarantine is not necessary. The arthropod vector, Ctenocephalides felis, or the cat flea, plays a major role in transmission among cats and to humans. The transmission risk to humans can be substantially reduced through elimination of flea infestations in companion animals. There are numerous recent reviews and case reports in the veterinary and medical literature reflecting increased recognition of this zoonotic agent. All this notwithstanding, many physicians and other providers may not be familiar with this agent and the potential spectrum of human disease; this may lead to delays in diagnosis and unnecessary diagnostic procedures. This article emphasizes the aspects of B. henselae infection, including a typical case report and a table with selected human case reports of unusual clinical manifestations from the published literature.

Abscess-forming granulomatous lymphadenitis: histological typing of suppurative granulomas and clinicopathological findings with special reference to cat scratch disease

In order to clarify the histological and immunohistochemical characteristics of suppurative granuloma in abscess-forming granulomatous lymphadenitis (AGL), and the relation between AGL and cat scratch disease (CSD), 36 cases of AGL were studied. The combined results showed that there were two types of suppurative granulomas. The suppurative granulomas histologically revealed small lymphocytes of predominantly T cell phenotype distributed among the epithelioid histiocytes bordering central necrotic areas in the suppurative granulomas. These suppurative granulomas could be further subdivided into two groups, mainly those with and without the intermingling of large transformed cells of B-cell phenotypes: Type B granuloma with large transformed B cells and Type A without large transformed B cells. Both types of granulomas were observed in a varying degree in most cases. According to the predominant type of granulomas, 36 patients with AGL were further classified into two groups: Group I of Type A dominance and Group II of Type B dominance. Warthin-Starry (WS) silver stain positive bacteria, which are said to be a causative agent of CSD, were present in about 50% of both groups. No Brown-Hopps' Gram-positive bacteria, fungus, toxoplasma, Chlamydia or Bacillus Calmette-Guérin antigen were found in any case. Clinically, there was no significant difference between these two groups. On the other hand, the detection of WS-positive bacteria seemed to have some relationship with the duration of disease and the history of exposure to cats, and 70% of AGL cases occurred in autumn without a single concurrent epidemic.

Monocytoid B lymphocytes and epithelioid cell clusters in abscess-forming granulomatous lymphadenitis. With special reference to cat scratch disease

In order to clarify the appearance of monocytoid B lymphocytes (MBLs) in abscess-forming granulomatous lymphadenitis (AGL) and the relation between AGL and cat-scratch disease (CSD), 48 cases of AGL were studied histologically. MBLs were present in about 50% of AGL cases. Warthin-Starry (WS) silver stain-positive bacteria, which are the causative agent of CSD, were present in 52.4% of AGL cases with MBLs and 59.2% of AGL cases without MBLs. The appearance of MBLs in AGL was not related to various clinical features, including disease interval from initial lymphadenopathy to lymph node biopsy. Histologically, epithelioid cell clusters appeared in about 70% of MBL-positive AGL cases, but were not observed in MBL-negative AGL. Therefore, a close interaction between MBLs and epithelioid cells in AGL is suggested, and we emphasize that the histological features of some AGL cases resemble those of toxoplasmic lymphadenitis.

Clinical and pathological features of bacillary peliosis hepatis in association with human immunodeficiency virus infection

BACKGROUND

Peliosis hepatis is characterized by cystic, blood-filled spaces in the liver and is seen in patients with chronic infections or advanced cancer and as a consequence of therapy with anabolic steroids. Cutaneous bacillary angiomatosis is a bacterial infection that occurs in patients with human immunodeficiency virus (HIV) infection; its histologic appearance is that of a pseudoneoplastic vascular proliferation.

METHODS

We studied liver tissue from eight HIV-infected patients with peliosis hepatis, two of whom also had cutaneous bacillary angiomatosis. For comparison we examined tissue from four patients who had peliosis hepatis without HIV infection. Tissues were examined histologically on routine sections and with special stains and electron microscopy.

RESULTS

The histologic features seen in peliosis hepatis associated with HIV infection, but not in the four cases unrelated to HIV infection, were myxoid stroma and clumps of a granular purple material that on Warthin-Starry staining and electron microscopy proved to be bacilli. The bacilli, which could not be cultured, were morphologically identical to those found in the skin lesions of cutaneous bacillary angiomatosis. The clinical courses of two of the patients with this "bacillary peliosis hepatis" indicate that it responds to antibiotic treatment.

CONCLUSIONS

HIV-associated bacillary peliosis hepatis is an unusual, treatable opportunistic infection, probably caused by the same organism that causes cutaneous bacillary angiomatosis. Our failure to find bacilli in non-HIV-associated cases implies that other pathogenetic mechanisms may also be responsible for peliosis hepatis.