Figure 1. Axial computed tomogram of the left humerus, performed on the 10th hospital day, shows extensive areas of osteolysis and cortical destruction of the proximal metaphysis. There is soft tissue swelling.
Figure 2. Frontal radiographs of the shoulders on the 10th hospital day show osteolytic metaphyseal lesions of both proximal humeri.
Figure 3. Radiographs of the long bones of the lower extremities (10th hospital day) show bilaterally symmetrical diaphyseal periostitis and metaphysitis of both distal femora and proximal tibiae, a pathognomonic sign of congenital syphilis.
On the second hospital day, the infant's serum VDRL test was 1:16. It rose 16-fold and reached a dilution level of 1:256 by the 10th hospital day. This result was 4 times higher than her mother's serum VDRL test result (1:64). Findings from a serum microagglutination test for cerebrospinal fluid were normal, as were results of a cerebrospinal fluid VDRL test. The diagnosis of congenital syphilis was established. The infant was treated with intravenous cefuroxime sodium, 150 mg/kg daily, because hematogenous osteomyelitis was initially suspected. After the positive serum VDRL test result was reported, cefuroxime was replaced by intravenous aqueous crystalline penicillin G, 300 000 µm/kg daily, which was given for 14 days. The infant recovered completely.
The incidence of early congenital syphilis remains relatively high.1,2 Early diagnosis and timely treatment are important to prevent serious complications. Congenital syphilis usually manifests during the first 3 months after birth with signs of fever, prolonged rhinitis, erythematous maculopapular rash of the palms and soles, hepatosplenomegaly, pseudoparalysis, Coomb-negative hemolytic anemia, leukocytosis, and monocytosis.3- 5 The definitive diagnosis is based on the results of a serum quantative nontreponemal test (VDRL or rapid plasma reagin) considered conclusive when the infant's titer is at least 4 times higher than that of the mother. The infant's antitreponemal immunoglobulin antibody test is also used for diagnosis.1 Bone involvement with bilaterally symmetrical periostitis and metaphysitis occurs in 95% of symptomatic infants.6,7 Asymmetric focal osteolytic metaphyseal lesions with sequestra or pathological fractures are also reported.8
To our knowledge, this is the first reported demonstration of diagnostic computed tomography of the skeletal lesions of early congenital syphilis. Computed tomography shows osteolysis and cortical destruction of the proximal left humerus and soft tissue swelling. These changes account for acute pain, which leads to pseudoparalysis in congenital syphilis.
Despite the clinical, laboratory, and later imaging signs, the 3-phase technetium 99m methylene diphosphonate bone scan in this patient repeatedly had negative findings. Increased accumulation radioactive tracer at the site of inflammation is characteristic of osteomyelitis.9 Lim et al10 reported a false-negative result from bone scan in a case of pseudoparalysis from congenital syphilis. The occurrence reflects the specific character of metaphyseal pathology. Histopathological analysis of the metaphysis in syphilis reveals an obliterative endarteritis secondary to binding of spirochetes to endothelial cells with inflammatory plasma cell–rich perivascular infiltration.11- 13 Spirochetes are identified in bone tissue by specific Dieterle stains.1,14 Obliterative vasculitis leads to decreased blood flow, atrophy, focal necrosis, and diffuse interstitial fibrosis.12,13,15 These changes may explain why the radioactive tracer does not accumulate at the site of syphilitic osseous lesions.
Accepted for publication June 27, 1999.
Reprints: Daniel Landau, MD, Department of Pediatrics B, Soroka Medical Center, PO Box 151, Beer Sheva 84101, Israel.
Radiological Case of the Month. Arch Pediatr Adolesc Med. 2001;155(5):613-614. doi:10.1001/archpedi.155.5.613