Primary intraosseous lymphoma at right femur

Lymphomas, the malignant neoplasms of the reticuloendothelial and lymphatic system, are classiied based on characterisitic morphological pattern, immunophenotypic pattern and sometimes distinctive chromosomal aberrations. Most of the intraosseous lymphomas should be metastatic, and primary intraosseous lymphoma is a rare type of lymphoma, which accounts for only about 5% extranodal lymphoma. It accounts for approximately 3% of all primary bone malignancies.


Correspondence:
Dr. Paricha Upadhyaya, MBBS, MD Additional Professor, Department of Pathology B.P. Koirala Institute of Health Sciences, Dharan, Nepal Email: paricha7@yahoo.comPrimary Bone lymphoma occurs commonly between 20 and 50 years of age and it shows a male preponderance with a male to female ratio of 3:2. 4 Diffuse large-B-cell lymphoma (DLBCL) accounts for the majority of cases of PBL. 5 Appropriate treatment depends on the histologic type and stage.Traditionally, irradiation has been used alone or in combination with chemotherapy. 6

CASE REPORT
A 54-years-old lady presented with pain over right thigh since 3 to 4 months which suddenly increased without inciting factors.The clinico-radiological differential diagnosis was ibrous dysplasia , Plasmacytoma or Metastasis and there was no organomegaly and lymphadenopathy.In Department of Surgical Pathology, specimen was submitted as multiple bits of bone and content of medullary canal, measuring altogether 6x5.5x1.2cm.Histological examination revealed multiple tissue bits composed predominantly of areas of necrosis and fragments of dead bony specules.The tumors was composed of monotonous population of atypical lymphoid cells of intermediate to large size and have rounded to cleaved nuclei with prominent nucleoli and scant amount of cytoplasm and were arranged in diffuse sheet punctuated by scattered tingible body macrophages.These atypical cells were seen surrounding central area of coagulative necrosis along with ibrin (ig.1A&B).Immunohistochemisty was positive for CD20 (ig.2) and negative for Bcl6.The histopathothological features supported by immunohistochemistry was those of Lymphoma-Diffuse Large B-cell type.

DISCUSSION
Primary lymphoma of bone is rare, and most lymphomas that involve bone are metastatic.The clinical presentation includes local pain, swelling and sometimes even a pathological fracture.The diagnosis is established by biopsy. 4The histological features of primary non-Hodgkin's lymphoma of the bone are identical to those of the conventional, non-osseous forms of non-Hodgkin's lymphoma.The hallmark attribute of lesion a replacement of the normal marrow constituents by neoplastic lymphoid tissue; the most common subtype is diffuse large B-cell lymphoma.
In order to be diagnosed as PLB the following criteria (known as Coley's criteria) should be met. 5A primary focus in a single bone

• Positive histological diagnosis
• No evidence of distal soft tissue or distal nodal involvement In the recent study that reviews a total of 60 cases of bone lymphoma during the period from 1998 to 2008, the most common site of involvement was femur (28.3%), followed by hip (16.6%) and humerus (10%). 7In addition, iliac bone and spine were ever reported to be involved. 8This is consistent with another study by Deshmukh et al., who   showed that femur (43%) was the most frequently involved site among 7 cases of bone non-Hodgkin lymphoma. 9We had the similar inding that thecase presented as bone pain had the involvement of lymphoma over her femur.

A B
In our case only femur bone was involved presenting as bone pain and no other soft tissue or lymph node involvement in clinico-radiological workup was found.

CONCLUSION
Lymphomas can develop in any location where lymphomatous tissue exists, but extranodal presentation in the lower limb and pelvis are uncommon.The majority of these are Large B-cell non-Hodgkin lymphomas.