Primary Lymphoma



Primary Lymphoma


G. Petur Nielsen, MD

Andrew E. Rosenberg, MD










This lymphoma of bone presents as a permeative, aggressive mass involving the acetabulum, ilium, ischium, and pubic ramus is shown. The tumor also extends into the intrapelvic soft tissues and gluteal muscles.






Large B cell lymphoma of the femoral head appears as a geographic zone that is tan-pale yellow and surrounded by hemorrhage. The tumor replaces the marrow and surrounds individual bony trabeculae.


TERMINOLOGY


Synonyms



  • Reticulum cell sarcoma (outdated)


  • Primary non-Hodgkin lymphoma of bone


Definitions



  • Primary lymphoma originating in bone ± soft tissue extension



    • Lymphoma should not be identified elsewhere; however, some studies include patients with regional lymph node involvement


    • No extraosseous distant disease should be identified within 4-6 months of initial diagnosis


  • Does not include leukemia involving bone


ETIOLOGY/PATHOGENESIS


Etiology



  • Most primary bone lymphomas are sporadic and of unknown etiology


  • Rarely reported in patients with HIV, longstanding osteomyelitis, or Paget disease of bone


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare and accounts for approximately 5% of primary malignant bone tumors and about 5% of all extranodal lymphomas



      • < 1% of all lymphomas arise in bone with slightly higher incidence in children


  • Age



    • Usually adults; approximately 50% are > 40 years; minority arise in children and adolescents


  • Gender



    • Slight male predominance


Site



  • Femur is most common location followed by pelvis, vertebrae, and humerus


  • Usually arises in metadiaphyseal region


  • Approximately 10-40% of cases are multifocal (polyostotic), producing several lesions in 1 bone or involving multiple bones concurrently


Presentation



  • Pain, erythema, swelling


  • May present with pathologic fracture


  • Tumors of axial skeleton may cause symptoms related to nerve impingement


  • 10% of patients have constitutional symptoms



    • More common with polyostotic disease


    • Fever, anemia, fatigue


Treatment



  • Currently treated with radiation and chemotherapy


  • Surgery is indicated for pathologic fracture


Prognosis



  • 10-year disease-free survival rate for large B-cell lymphoma approaches 75%


  • Lymphomas with follicular center-like immunophenotype may have better prognosis


  • Prognosis for anaplastic large cell lymphoma is poor


IMAGE FINDINGS


Radiographic Findings



  • Large, lytic and destructive


  • May erode cortex and form soft tissue mass


  • Bone margins are “moth eaten” or permeative


  • Onion skin periosteal reaction may be present


  • Because of highly infiltrating growth pattern, soft tissue mass tends to be concentrically distributed around affected bone


  • In some cases, tumor may elicit extensive medullary sclerosis



  • Occasionally, findings on plain radiography are minimal with abnormalities only recognized on bone scan, CT, or MR


MR Findings



  • Provides important information regarding extent of bone and soft tissue involvement


CT Findings



  • Helpful in identifying extent of disease


MACROSCOPIC FEATURES


General Features



  • Centered in medullary cavity


  • May destroy cortex and extend into soft tissue


  • Moderately firm, gray-white and fleshy, frequently with areas of necrosis


MICROSCOPIC PATHOLOGY


Histologic Features



  • Exhibits same features as nodal lymphomas and are classified accordingly


  • Diffuse large B-cell lymphoma is most common type by far in both adults and children



    • Lymphoblastic lymphoma is 2nd most common type to arise in children (40% of cases)


  • Anaplastic large cell lymphoma is rare but most common primary T-cell lymphoma of bone


  • Various other types of lymphomas including Hodgkin lymphoma can rarely arise in bone


  • Lymphomas frequently contain scattered nonneoplastic small lymphocytes


  • Because of extensive necrosis or crush artifact that may be present, several biopsies may be required before definitive diagnosis can be rendered


ANCILLARY TESTS


Immunohistochemistry



  • Immunoprofile varies according to type


  • Large B-cell lymphomas express leukocyte common antigen (LCA) and B-cell markers


  • Anaplastic large cell lymphoma may be positive or negative for ALK



    • ALK(+) tumors mainly affect children whereas ALK(−) tumors affect adults


  • Lymphoblastic lymphoma may not express LCA and can be CD99(+)


DIFFERENTIAL DIAGNOSIS


Round Cell Lesions



  • Osteomyelitis, Langerhans cell histiocytosis, Ewing sarcoma/primitive neuroectodermal tumor, metastatic small cell carcinoma, neuroblastoma, rhabdomyosarcoma, and other round cell malignancies


  • Immunohistochemistry, electron microscopy, and cytogenetic analysis may be necessary to distinguish amongst these possibilities


DIAGNOSTIC CHECKLIST


Pathologic Interpretation Pearls



  • Think lymphoma if malignant round cell tumor with extensive necrosis or crush artifact



SELECTED REFERENCES

1. Singh T et al: Primary bone lymphoma: a report of two cases and review of the literature. J Cancer Res Ther. 6(3):296-8, 2010

2. Glotzbecker MP et al: Primary non-Hodgkin’s lymphoma of bone in children. J Bone Joint Surg Am. 88(3):583-94, 2006






Image Gallery




Imaging Features






(Left) Radiograph shows lymphoma of bone manifesting as an ill-defined zone of medullary sclerosis image. The cortex is intact with no identifiable periosteal reaction. (Right) Radiograph shows lymphoma of bone of the proximal tibial metaphysis appearing as a poorly defined lytic lesion with endosteal resorption anteriorly and posteriorly image. The distal component is indistinct with an area of sclerosis image. The cortex and periosteum are intact, and there is no soft tissue component.






(Left) Fluid-sensitive coronal MR with fat saturation shows that the bone lymphoma replaces the marrow of the proximal tibial diaphysis. The small hyperintense soft tissue component with intact-appearing cortex is a manifestation of the permeative nature of the lesion image. (Right) Axial T1WI MR shows a lymphoma that has a hypointense signal within the medullary cavity of the tibia image. The tumor appears to be confined to the bone, and the cortex seems to be intact.

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Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Primary Lymphoma
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