Discussion:
PB-DLBCL is rare extranodal lymphoma which accounts for 2 percent of all lymphomas in adult and the most common symptom is bone pain.
In this article, we report a 34-year-old man who presented progressive hip pain and osteolytic bone lesions. He was later diagnosed with primary diffuse large B-cell bone lymphoma ,previous studies had also suggested that osteomyelitis unusually mimics PB-DLBCL (5-7)
Several rationales led us to believe that the previous workup session was insufficient and another approach is needed to be taken, hence we decided to perform an open biopsy, one of the main reasons to do so was the fact that bone pain was progressive and unresponsive to the standard antibiotic regimen.
On the other hand Radiologic changes, such as osteolytic lesions, were progressive and despite regular treatment for osteomyelitis the lesions progressed and contained sequestrum as the disease spread. this pattern of progress was also observed between the two MRI scans that were taken in the 6 months. These changes include an extraosseous extension of the lesion that had led to asymmetric soft tissue swelling. These patterns of change are usually seen with neoplastic lesions rather than infectious ones.
In recent studies, it has been suggested that An ESR level of 60 mm/h is an optimal cutoff level for suspected osteomyelitis. (74 % sensitive and 56% specific), our patient had ESR levels below the threshold, thus osteomyelitis seemed unlikely. (8)
Other reasons such as lack of predisposing factors for osteomyelitis (i.e., Long term skin infections, Prosthetic joints, use of intravenous drugs, etc.) and abrupt beginning of the symptoms made our case less probable for osteomyelitis. Being safer and almost equally accurate it has been suggested by the literature that core needle biopsy is a more preferable method of obtaining bone tissue sample than open biopsy. it is also both less invasive and cost-effective. (9)
unfortunately, though in our case core needle biopsy couldn’t help provide an accurate diagnosis.
we have come to conclude that the first two biopsies were taken from the rim of the lesion, thus making the sample redundant and inefficient. the result was only suggestive for non-specific lymphocyte aggregation. In such circumstances, open biopsy seems suitable for patients who are highly suspicious of bone tumors and core needle biopsy is inconclusive and non-diagnostic. (10)