Case Presentation:
a 34-year-old man with no significant past medical history complaining of dull low back pain and non-traumatic progressive right hip pain which he had for 6 months was referred to our clinic. He described his pain as dull low back pain and he also localized his hip pain on the anterior part of the right hip, the pain also radiated to the buttock and groin, his pain also exacerbated with weight-bearing activities, and didn’t relieve even with rest or pain killers such as morphine. the patient had been bedridden for a month as the pain had gotten excruciating. Meanwhile, the patient had no constitutional symptoms.
the examination revealed decreased range of motion on his right hip joint and tenderness over the anterior joint line, adjacent soft tissue to the right hip joint was also swollen and asymmetric compared to the left side, other physical exams were unremarkable.
in the previous workup and admission 6 months before referral, the Magnetic resonance imaging(MRI) had demonstrated diffuse abnormal high-intensity signals on T2 and proton density fat saturation in the right iliac and superior ramus of pubis was seen, this was accompanied by a high-intensity signal on the peripheral soft tissue along with periosteal reaction.
abnormal high-intensity signals in the medulla of the femur and sequestration in the iliac bone were also reported.
according to the imaging findings which were suggestive for infiltrative disorders. A core needle biopsy was obtained from the lesion in the right acetabulum the pathologic assessment reported unremarkable spongy bone with cellular marrow tissue and a benign lymphocytic aggregation.
these findings were suggestive of osteomyelitis, and subsequently, he was treated with antibiotics which turned out to be ineffective.
3 months after the first admission as the pain had progressed, he has admitted again for further evaluation and the imaging revealed progression of the lesion. ( Figure 1)
He became a candidate for another biopsy that showed inflamed fibro connective tissue and fibrin exudative substances which were compatible with osteomyelitis. He was treated again with broad-spectrum antibiotics for another 6 weeks.
As the patient’s overall health and symptoms showed no sign of remission, he was referred to our clinic for further evaluation. He was admitted and samples were taken. laboratory results showed the following: white blood cell (WBC) count 5700/µl (band+segment 59.0 %, mono 10.0 %, lymph 28.0 %); hemoglobin (Hgb) 11.5 g/dl; platelet count (Plt) 2.83 × 104/µl; lactate dehydrogenase (LDH) 355 IU/l (normal range 150–500 U/L); AST 13 IU/L; ALT 16 IU/l; C-reactive protein (CRP) 25  mg/dl; (ESR) 32  mm/h.
for evaluating the lesions a whole bone scan with TC-99m was performed which was suggestive for chronic arthritis and osteomyelitis in sacroiliac joint, right acetabular bone especially in the acetabular roof, and the right iliac crest, it was also suggestive for probable bone tumors. (Figure 2)
According to the clinical findings and the fact that previous core needle biopsies were inconclusive and unhelpful, we decided to perform an open biopsy to rule out primary bone malignancies.
The open biopsy of the lesion and the pathologic assessment suggested primary bone DLBCL.
Immunohistochemical results were as following LCA +, CD20+, Bcl-6+, Bcl 2 +, CD3- , MUM-1+, CD99 -, vimentin - , CD10 -, and Ki67+ (90%),this was consistent with DLBCL, non-germinal center B-cell-like (non-GCB).(figure 3 )
using the Ann Arbor staging, the patient was staged at I EA level of the disease with no other distant metastasis.
The patient received his first cycle of chemotherapy with rituximab, cyclophosphamide, Adriamycin, vincristine, prednisone (R-CHOP), and concurrent intrathecal chemotherapy with Cytarabin, methotrexate, and hydrocortisone. meanwhile, He also became a candidate for radiotherapy (RT).