[Staging and evaluation of bone marrow involvement in lymphoma]

Staging of lymphoma is important for predicting the prognosis and deciding on the treatment strategy for each patient. The Ann Arbor classification and its Cotswolds revised version are widely used, and now comprise the standard staging system for lymphoma. Bone marrow involvement is one of the most important factors in the staging system. Pathological patterns of lymphoma cell infiltration in the marrow are categorized into the following types: 1) nodular/patchy, 2) paratrabecular, 3) interstitial, 4) diffuse, and 5) intrasinusoidal. The frequency and patterns of bone marrow involvement in association with the subtypes of lymphoma are reviewed. PET/CT analysis has become a powerful method for staging lymphoma, and may complement or substitute for bone marrow biopsy in some subtypes of lymphoma.