CASE REPORT A 27-month-old female was evaluated because of a history of recurrent sterile abscess formation at the sites of routine hildhood vaccinations. She had an uneventful course after her first series of vaccinations at age 2 months, which included APTACEL (diphtheria and tetanus toxoids and acellular pertussis vaccine adsorbed; Sanofi Pasteur Inc, Swiftwater, PA), POL (inactivated poliovirus vaccine; Sanofi Pasteur Inc), COMVAX (Haemophilus b conjugate and hepatitis B vaccine; Merck, hitehouse Station, NJ), and Prevnar (heptavalent pneumococcal conjugated vaccine; Wyeth Pharmaceuticals Inc, Philadelphia, PA). One month after the patient’s second set of vaccinations at age 4 months, she developed a draining abscess on her left thigh t the site of DAPTACEL and IPOL administration. Her right thigh, where she received COMVAX and Prevnar, was naffected. The lesion healed after an incision and drainage and a course of oral antibiotics. At age 6 months, the patient received DAPTACEL and Prevnar in her right thigh. One month later, she developed an abscess n that extremity. The lesion was incised. Wound culture and Gram’s stain were negative, and she was given an empiric course of ntibiotics. At age 18 months, she received the MMRII (measles, mumps, and rubella virus vaccine; Merck), with no complications. At age 2 years, she received COMVAX in her left arm, and 1 month later developed an abscess at the site. The lesion ealed after an incision and drainage, but without antibiotics. Wound culture was negative, and a tissue biopsy was obtained from he base of the abscess (Figure). The patient had no history of other skin lesions or frequent infections. Her mother reported that umbilical cord separation as not delayed. Quantitative immunoglobulins and IgG subclasses were normal at age 8 months. The white blood cell count t that time was 10,300, with 20% neutrophils and 72% lymphocytes. Flow cytometry for CD11b/CD18, performed to exclude eukocyte adhesion defect type 1, was normal. It was felt that the patient’s hypersensitivity to a common ingredient in DAPTACEL, IPOL, COMVAX, or Prevnar vaccines as the cause of the recurrent lesions. Aluminum, formaldehyde, 2-phenoxyethanol, and thimerosal were considered as possible causes f the reactions. Notably, the MMRII vaccine, which contains gelatin and neomycin, was not ssociated with abscess formation in this patient. Patch testing was performed for aluminum (2% aluminum chloride solution), for ndiluted DAPTACEL, and for a normal saline control by applying 0.1 mL of each olution to 1-cm gauze patches, applied to the upper arm and occluded with Tegaderm. he patches were examined at 72 hours. The control patch was negative, and minimal rythema was noted at the DAPTACEL site. A moderate reaction, characterized by rythema, multiple papules, and scattered vesicles, was seen at the aluminum chloride site. atch testing on a negative control subject was negative for all 3 solutions. We diagnosed aluminum hypersensitivity in our patient, and recommended that she ot receive any more aluminum-containing vaccines.