An unusual cutaneous presentation of cat-scratch disease

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.

Skin diseases associated with Bartonella infection: facts and controversies

The genus Bartonella is composed of a series of species and subspecies. Ten of them are responsible for human infections. The best-identified diseases are cat scratch disease (B henselae and possibly B clarridgeiae), trench fever (B quintana), bacillary angiomatosis (B quintana and B henselae), and the spectrum of verruga peruana, Carrion disease, and Oroya fever (B bacilliformis). Controversies exist about the implication of a few other microorganisms being involved in these diseases. Several other conditions have been associated with the presence of Bartonella spp, but these observations await confirmation.