Várias dermatoses são consideradas idiopáticas. Muitas vezes, afecções como eritema nodoso ou eritema multiforme, por exemplo, não podem ter sua etiologia definida. A infecção humana por Bartonella spp. pode determinar várias expressões clínicas sindrômicas. A partir de um caso de angiomatose bacilar com documentação clínica, histológica e ultra-estrutural, foi feita a revisão da literatura médica para avaliar os critérios diagnósticos disponíveis para a infecção por esses agentes. Conclui-se que a avaliação histológica é, na prática, um importante e útil método diagnóstico, especialmente quando a sorologia não estiver disponível.

Several dermatoses are considered idiopathic diseases. Many times lesions such as erythema nodosum or erythema multiformis, for example, cannot have their etiology defined. Human infection caused by Bartonella spp. may determine several clinical syndromic expressions. Starting with a clinically, histologically and ultrastructurally documented bacillary angiomatosis case, a review of medical literature was undertaken to evaluate the available diagnostic criteria regarding infection caused by these agents. Histological evaluations were concluded to be, practically speaking, an important and useful diagnostic method, especially when serology is not available.

The human bartonelloses are a group of diseases with a rapidly increasing clinical spectrum. Well known manifestations such as Carrion's disease, trench fever, cat-scratch disease, and bacillary angiomatosis are examples of Bartonella spp. infection. Along with these diseases, recurrent bacteremia, endocarditis, septicemia, erythema nodosum, erythema multiforme, trombocytopenic purpura and other syndromes have been reported having been caused by bacteria of this genus. The infectious process and the pathogenesis of these microorganisms are poorly understood. The bartonelloses may have a benign and self-limited evolution in a host, or a potentially fatal one. These bacteria can provoke a granulomatous or an angioproliferative histopathologic response. As these diseases are not yet well defined, we have reviewed the four main human bartonelloses and have examined unclear points about these emergent diseases.