Immunohistochemistry in Staging Bone Marrow Biopsy Specimens: a Useful Adjunct for Morphological Diagnosis in Non Hodgkin’s Lymphoma

Background: Morphological examination of bone marrow trephine biopsy represents a standard method for non-Hodgkin’s lymphomas (NHL) staging. Immunohistochemistry staining of bone marrow trephine specimens has been widely used in haematological malignancies due to its high applicability and sensitivity at diagnosis. However, the routine use of immunohistochemistry in the clinical settings when there is no obvious morphological (light microscopic) evidence of lymphoma in the bone marrow trephine, is not yet well established universally. We assessed the value of immunohistochemistry (by using a standard basic panel of anti-CD20 and anti-CD3 staining) in detecting involvement by NHL in routinely processed bone marrow trephine specimens with no obvious morphological involvement with lymphoma. Methods: This study involved 56 randomly selected paraffin wax embedded, formalin fixed bone marrow trephine specimens between February 2011 and September 2013 from three teaching hospitals in Northeast, UK. 49 patients (87%) had B-cell NHL: diffuse large B cell lymphoma (DLBCL) 43% (n=24), follicular lymphoma (FL) 18% (n=10), marginal zone lymphoma (MZL) 9% (n=5), mantle cell lymphoma (MCL) 7% (n=4), lymphoplasmacytic lymphoma (LPL) 6% (n=3) and Burkitt’s lymphoma (BL) 6% (n=3). 7 cases (12%) had T/NK lymphomas. There was no obvious morphological evidence of bone marrow infiltration as all samples were reviewed by two examiners. All specimens were stained with the anti-CD20 and anti-CD3 antibodies. Results: Concordant results were found in 50 samples (89%), as both investigations were reported negative. 6 of the 56 cases (11%) with no morphological evidence of involvement by NHL on routine stains, were positive on immunohistochemistry. Considering histology, discrepant results were noted more frequently in T/NK lymphomas (42%; 3 of 7 cases) comparing to B-cell NHLs (6%; 2 cases of DLBCL and 1 case of FL). In all six cases the lymphoid infiltrates had diffuse pattern. Conclusions: Our results indicate that immunohistochemistry can detect a subgroup of NHL patients with bone marrow involvement beyond discriminatory level of conventional stains (Haematoxylin & Eosin and Giemsa), thereby contributing to accuracy of staging and treatment planning. Rational application of immunohistochemistry is a cost-effective & valuable method in routine investigation of staging bone marrow trephine biopsies. Disclosures No relevant conflicts of interest to declare.