This is a bone marrow biopsy from 73-year-old female presenting with pancytopenia and fevers.  There was no evidence of any significant lymphadenopathy.  There was only moderate splenomegaly.  The findings in the bone marrow biopsy shown here in this case are typical of T-cell/histiocyte rich large B-cell lymphoma involving the bone marrow, specifically the so-called "micronodular" variant.  

This specific variant is known to cause isolated splenomegaly with bone marrow involvement in the form of multiple small nodular atypical lymphohistiocytic aggregates that may sometimes be mistaken for sarcoidosis.  Careful examination of the bone marrow biopsy within these aggregates to look for large abnormal cells and additional immunostains including CD20 will help uncover the presence of rare large atypical neoplastic B cells within these aggregates.  This lymphoma is often a pitfall and was initially thought to represent an abnormal T-cell process based on numerous T cells within the aggregates and outside of these aggregates in the interstitium of the bone marrow.

REF:
Dogan A, Burke JS, Goteri G, Stitson RN, Wotherspoon AC, Isaacson PG. Micronodular T-cell/histiocyte-rich large B-cell lymphoma of the spleen: histology, immunophenotype, and differential diagnosis. Am J Surg Pathol. 2003;27(7):903–911.