Cutaneous bacillary angiomatosis is the most common clinical form of bacillary angiomatosis. Skin lesions present as red papules, subcutaneous nodules, or cellulitic plaques [2-4]. Bartonella infection has also been seen in the lymph nodes, liver (bacillary peliosis hepatis), spleen, bone, heart, central nervous system, oropharynx, larynx, endobronchus, duodenum, and blood [3-5].

We report the first known case of bacillary angiomatosis of the colon. Our patient was a middle-aged man with the acquired immunodeficiency syndrome (AIDS), bloody diarrhea, and no cutaneous involvement. This case highlights a new treatable cause of diarrhea and intestinal bleeding in patients with AIDS.

Case Report

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A 60-year-old homosexual man with AIDS and Crohn disease in remission was seen after having had abdominal cramps and pain, tenesmus, and bloody diarrhea for 8 weeks. Colonoscopy done 2 years earlier had shown deep serpiginous ulcerations in the rectosigmoid region. Biopsy specimens had shown mucosal erosions and hemorrhage and a lymphoplasmacytic infiltrate. The endoscopic and histologic features of the remainder of the colon and the terminal ileum were normal, compatible with Crohn proctosigmoiditis. The patient was treated with hydrocortisone enemas, which relieved his symptoms. No subsequent endoscopic evaluation was done.

The patient's diarrhea was small in volume and occurred several times per day. It did not correlate with meals or abate with fasting. The patient's symptoms had begun during a trip to Korea and had not been alleviated by antidiarrheal agents and a 2-week course of ciprofloxacin hydrochloride. The patient had no known recent cat scratch or bite or exposure to lice.

Laboratory tests showed a hemoglobin level of 730 g/L, a hematocrit of 0.22, a mean corpuscular volume of 71 fL, and a CD4⁺ count of 189 cells/mm³ (0.189 x 10⁹/L). The results of stool specimen studies for culture, ova and parasites, Clostridium difficile toxin, cryptosporidium, and acid-fast bacilli were negative. We saw multiple erythematous nodules with intervening ulcerations in the rectosigmoid colon by sigmoidoscopy (Figure 1, top). The results of endoscopic biopsy cultures for cytomegalovirus and herpes simplex virus were negative. Histologic examination of the biopsy specimens showed ulceration with marked acute and chronic inflammation adjacent to mucosa that appeared normal (Figure 1, bottom left). Ulcerated areas contained prominent neovascular channels resembling those seen in granulation tissue (Figure 1, bottom left). Within the ulcers, many small, gram-negative, rod-shaped bacterial organisms were stained positive by Warthin-Starry silver stain (Figure 1, bottom right) but not by Ziehl-Neelsen or Grocott-Gomori methenamine silver stain. No representative tissue sample was available to further confirm Bartonella infection through electron microscopy, immunocytochemical staining, or polymerase chain reaction (PCR) detection of Bartonella-specific DNA sequences.

View larger version (134K): [in this window] [in a new window]   Figure 1. Colonic bacillary angiomatosis. Top left and top right. Endoscopic appearance of several reddish nodules with intervening ulcerations in the rectosigmoid colon. Bottom left. Colonic biopsy specimen. The colonic mucosa has been replaced by an acute inflammatory cell infiltrate with abundant thin-walled fibrovascular vascular channels (Vs) lined by prominent endothelial cells (arrows). Hematoxylin and eosin stain; original magnification x 400. Bottom right. Warthin-Starry stain of colonic biopsy specimen. Areas of mucosal destruction contain many Warthin-Starry positive rod-shaped organisms (arrows) consistent with a diagnosis of bacillary angiomatosis. Warthin-Starry stain; original magnification x 1000.

Treatment with erythromycin was changed after 2 days to doxycycline, 100 mg twice daily, because of gastrointestinal intolerance. The patient's symptoms improved within 4 days, and the bloody diarrhea resolved within 2 weeks. Doxycycline therapy was maintained for 3 months.

Three months after the diagnosis of colonic bacillary angiomatosis, the patient presented with intractable, nonbloody, small-volume diarrhea. Sigmoidoscopy showed persistent red nodules and ulcerations in the rectosigmoid colon and many small aphthous ulcers in the descending colon. Microscopic examination showed features of nonspecific colitis, including acute and chronic inflammation of the lamina propria. However, the histopathologic changes characteristic of bacillary angiomatosis were absent, and Warthin-Starry staining for organisms had negative results. Treatment of inflammatory bowel disease with steroids improved the diarrhea. Long-term follow-up was not possible because the patient had a fatal pulmonary embolus shortly there-after.

Discussion

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In 1983, Stoler and colleagues [6] first described bacillary angiomatosis in a 32-year-old man with AIDS who presented with fever and multiple subcutaneous nodules. Histologic evaluation and Warthin-Starry staining confirmed the diagnosis, and erythromycin treatment was curative.

Many extracutaneous sites of bacillary angiomatosis have since been described. A duodenal infection manifested by a single 3-mm red nodule [5] and an intra-abdominal mass associated with gastrointestinal hemorrhage [7] have both been reported. No cases of symptomatic colonic involvement had been reported before our case.

In our patient, the colonic bacillary angiomatosis appeared as nonspecific ulceration on histologic examination (Figure 1, bottom left). The presence of lobular capillary proliferation—characteristic of the condition in its involvement of skin and other sites [2-6]—closely simulated granulation tissue (Figure 1, bottom left). Ulceration of individual lesions is likely to superimpose a nonspecific pattern of inflamed granulation tissue, complicating the etiologic diagnosis. These histopathologic considerations impede detection of the disease in tissue biopsy specimens. Histologic and endoscopic features along with clinical correlation are essential in making the diagnosis. When appropriate, Warthin-Starry staining with electron microscopic, immunocytochemical staining, or PCR detection of bartonella-specific DNA sequence confirmation should be done.

Clinically and histologically, cutaneous bacillary angiomatosis and verruca peruana (Peruvian warts), the second stage of B. bacilliformis infection, are similar [8]. In chronic bartonellosis, an angiogenic factor is released that mediates vasoproliferation [9]. A similar angiogenic factor may be responsible for the vascular proliferation seen in bacillary angiomatosis [10]. Rochalimaea species were recently reclassified into the genus Bartonella because of similar genotypic and phenotypic characteristics [1].

Our patient had angiomatous nodules in the distribution of a Crohn proctosigmoiditis that had been described previously. Because the affected intestinal mucosa in inflammatory bowel disease contains oxygen-free radicals and activated B lymphocytes and T lymphocytes with the release of high levels of cytokines and inflammatory mediators, superinfection with bacillary angiomatosis would not have been expected [11, 12]. However, infection with the human immunodeficiency virus (HIV), by reducing the intestinal CD4 T-cell function, may have altered the intestinal mucosal immune response. In fact, remission in Crohn disease induced by HIV infection has been reported [13]. No cases of colonization with Bartonella in patients with inflammatory bowel disease have yet been reported.

This is the first report of Bartonella infection of the colon. The histologic findings were similar to those seen in Bartonella infection of the skin and lymph nodes [2-6]. Physicians caring for immunocompromised patients and patients with AIDS should include bacillary angiomatosis in the differential diagnosis of diarrhea with gastrointestinal bleeding. Warthin-Starry staining is essential for confirming the diagnosis. The importance of making the diagnosis is underscored by the availability of effective treatment with erythromycin or doxycycline [3, 4, 6].

Dr. Hunt: University of Pittsburgh Medical Center, Division of Internal Medicine, 190 Lothrop Street, Room 166 Lothrop Hall, Pittsburgh, PA 15261.

Dr. Finkelstein: University of Pittsburgh Medical Center, Department of Pathology, 200 Lothrop Street, A616 Scaife Hall, Pittsburgh, PA 15213.