Cat at home? Cat scratch disease with atypical presentations and aggressive radiological findings mimicking sarcoma, a potential diagnostic pitfall

Cat-scratch disease: a rare cause of osteomyelitis

“…As such, fever and bone pain that develop during typical CSD, must raise suspicion towards a diagnosis of B. henselae osteomyelitis 15. However, these unspecific clinical features overlap with those of malignant disease, so that bone and soft tissue tumours are usually among the differential diagnoses of atypical CSD,7 8 16 as initially suspected in our patient, whose clinical evaluation started by exclusion of a neoplastic process.…”

“…Regarding radiological exams in osteomyelitis, MRI seems to be the best choice16 because it can identify the infection site,11 and characterise bone and surrounding tissue lesions; nevertheless, the differential diagnosis between neoplastic and infectious disease is not always possible based solely on MRI 13. In these cases, typical granulomatous inflammation on histopathological analysis of biopsy specimens16 may help in the distinction, as seen in our case.…”

“…Identifying B. henselae in a patient with CSD is rarely achievable17 since its incubation period is long, making it difficult to obtain positive cultural results,1 15 as happened in our clinical case. Therefore, it is imperative for physicians to have a broad approach: clinical history and physical findings must be complemented with radiological, histopathological and serological results as well as, more recently, the ones provided by molecular biology 8 16…”

“…Presently, however, newer and better tests have improved the identification of B. henselae ,4 namely serology and PCR testing 16. The former is the gold standard for diagnosis1 15 while the later supports and strengthens the diagnosis by identifying the bacteria in the affected site or concomitant lymphadenopathy 1 13.…”

“…This is possible because, although serology is the cornerstone for CSD diagnosis (due to its high sensitivity and specificity),1 a positive PCR test allows treatment guidance (due to its high specificity despite its good, although variable, sensitivity) 5 9. Nonetheless, even positive serology and/or molecular tests do not rule out concomitant disease, such as malignancy, and further investigation may be necessary 16. As such, and despite being advised to avoid invasive explorations if a Bartonella osteomyelitis diagnosis is established without them, clinicians must remember that these are needed when suspicion remains towards the existence of concomitant disease 1 15…”