Bacillary angiomatosis associated with pseudoepitheliomatous hyperplasia.

Bacillary angiomatosis is an opportunistic bacterial infection caused by either Bartonella henselae or B. quintana. The classic histologic presentation of bacillary angiomatosis involves three components: a lobular proliferation of capillaries with enlarged endothelial cells, neutrophilic debris, and clumps of finely granular material identified as bacteria with staining techniques. Pseudoepitheliomatous hyperplasia is a histologic reaction pattern characterized by epithelial proliferation in response to a variety of stimuli, including mycobacterial, fungal, and bacterial infections. We describe a case of bacillary angiomatosis associated with pseudoepitheliomatous hyperplasia in an immunocompromised patient with Acquired Immunodeficiency Syndrome. Histologic examination of a finger lesion demonstrated a capillary proliferation with neutrophilic debris and characteristic amorphous granular deposits. Warthin-Starry and Giemsa staining revealed clumps of coccobacilli. Cervical lymph node tissue also revealed organisms identified as Bartonella with PCR techniques. Stains and cultures for acid fast bacilli, fungus, and bacteria were negative. To our knowledge, there has been only one other report of bacillary angiomatosis presenting with pseudoepitheliomatous hyperplasia. We conclude that the differential diagnosis of entities associated with pseudoepitheliomatous hyperplasia should be expanded to include bacillary angiomatosis.