Syphilitic osteomyelitis in a patient with HIV and cognitive biases in clinical reasoning: A case report

Diagnosing multifactorial, multidimensional symptoms unexplained by presumptive diagnosis is often challenging for infectious disease specialists. PATIENT CONCERNS: We report a rare case of a 30-year-old Japanese bisexual man with a history of virally suppressed human immunodeficiency virus and syphilis infections who developed chest pain and an erosive lesion under the lower midline jaw. DIAGNOSIS: Imaging examinations revealed erosive lesions on the sternum and left the ninth rib. Biopsy and polymerase chain reaction testing of sternal tissue specimens were noncontributory. However, due to elevated rapid plasma regain levels, a diagnosis of syphilitic osteomyelitis and gumma of the jaw was made. INTERVENTIONS: The patient was treated with 5 weeks of intravenous ceftriaxone and then with 8 weeks of oral amoxicillin. OUTCOME: After the antibiotic treatment, bone pain disappeared. We conducted a literature review on syphilitic osteomyelitis, and all of the articles included were case reports. Approximately half of the 46 patients with syphilitic osteomyelitis had HIV coinfection, and 10 (22%) patients lacked signs of early syphilis. Given its rarity, clinical data to establish appropriate guidelines for diagnosing and treating syphilitic osteomyelitis are still lacking. Cognitive biases, such as anchoring, cognitive overload bias, and premature closure, may contribute to diagnostic delays. LESSONS: In cases of idiopathic multiple bone lesions, syphilis must always be ruled out, and clinicians should guard against cognitive pitfalls when diagnosing rare diseases.