ASPEN, COLO. — Hepatosplenic cat-scratch disease is a diagnostic possibility worth bearing in mind in a child with fever of unknown origin and prominent abdominal pain, Dr. Karen Dahl said a conference on pediatric infectious diseases sponsored by Children's Hospital, Denver, and the University of Colorado.
“Hepatomegaly is seen about half the time in these patients. Splenomegaly is even less common. Typically, liver function tests are normal. So it's a little bit of a silent disease except for the pain they may have, which may cause you to pursue ultrasound for other possible diagnoses,” noted Dr. Dahl, chief of the pediatric infectious disease division at Helen DeVos Children's Hospital, Grand Rapids, Mich.
The literature suggests that children with hepatosplenic cat-scratch disease (CSD) benefit from prompt antimicrobial therapy, which shortens the duration of fever, although these are retrospective nonrandomized studies, she added.
Dr. Dahl noted that in one series of 19 patients with hepatosplenic CSD with serologically confirmed Bartonella henselae infection, 13 had microabscesses of both liver and spleen, while the remaining 6 were evenly divided between those with lesions of one organ or the other. None of the patients had a solitary lesion.
All 19 patients had an elevated erythrocyte sedimentation rate. Thirteen presented with abdominal pain, mostly left-sided, although the chief complaint in all 19 patients was fever of 1–4 weeks' duration. Only five patients had lymphadenopathy. None had the classic CSD inoculation site papule.
All patients were treated with gentamicin, rifampin, and/or trimethoprim/sulfamethoxazole in various combinations. Defervescence occurred within 1–5 days after starting therapy, even in patients with prolonged fever. The fastest response was seen with rifampin monotherapy at 15–20 mg/kg per day (Clin. Infect. Dis. 1999;28:778–84).
The largest published CSD treatment study involved 268 patients with a mixed bag of disease manifestations. Fourteen antimicrobials, including various cephalosporins and penicillins, were identified as being of little or no value in the retrospective study.
Indeed, only four agents were deemed effective by investigators: rifampin, ciprofloxacin, gentamicin, and trimethoprim/sulfamethoxazole. Response rates ranged from a high of 87% with rifampin to 58% with trimethoprim/sulfamethoxazole (Pediatr. Infect. Dis. J. 1992;11:474–8).
However, azithromycin wasn't among the drugs included in this study. And it so happens azithromycin showed significant efficacy in the only randomized double-blind placebo-controlled trial ever conducted in CSD. The study, which involved 29 patients with CSD chronic lymphadenopathy, showed 7 of 14 patients who received a 5-day course of azithromycin had a significant reduction in lymph node size within 30 days, compared with 1 of 15 on placebo (Pediatr. Infect. Dis. J. 1998;17:447–52).
These studies—all of which are old, small, and/or uncontrolled and retrospective—highlight the shortcomings of the CSD literature.
“In some ways you can't go wrong with cat-scratch disease; the literature will support you no matter what you choose to do,” Dr. Dahl quipped. “The most important thing is to keep your index of suspicion high if you live in an area where cat-scratch disease is common. Don't necessarily exclude cat-scratch because there's no lymphadenopathy or they don't tell you they've been scratched by a kitten. Your serologic diagnosis will be very useful.”