Response to: Pagni F, L’Imperio V, Cazzaniga G, et al. Nodal monoclonal CD5 positive B-lymphocytosis and toxoplasma lymphadenitis: another variant in the spectrum of infectious lymphadenitis in patients with chronic leukemia/small lymphocytic lymphoma. Expert Rev Hematol 2015;8(5):563-65.
Dear Sir,
I thank the authors (Pagni et al.) for their insightful comments and the opportunity to clarify a number of points related to the descriptive term ‘atypical lymphoid proliferation’. The authors (Pagni et al.) present an interesting case of Toxoplasma infection in a 55-year-old Caucasian man with axillary and cervical lymph node enlargement. Based on routine histology, this case would probably be classified as atypical lymphoid proliferation. However, the diagnosis of Toxoplasma infection was established based on further studies including radiological (ultrasound, Computed Tomography, Computed Tomography-Positron Emission Tomography) and laboratory investigations (flow cytometry and immunophenotyping). On through clinical follow-up, the disease did not declare itself as lymphoma (no peripheral lymphocytosis or an abnormal lymphoproliferative process involving the bone marrow). In sum, the authors agreed with me about the need of a descriptive term such as ‘atypical lymphoid proliferation’ for some borderline lymphoproliferative lesions with unrevealing histology.
In 1993, I was a pathology resident (Department of Pathology, Assuit University Hospitals) when I came across an essentially similar challenging case scenario. Briefly, a 35-year-old female patient (she was, in fact, one of our colleagues at the hospital) presented with axillary lymphadenopathy. The histology was unrevealing with a partial effacement of the nodal pattern by banal looking polymorphous lymphoid infiltrate, but with rare large atypical cells with pink cytoplasm, vesicular nuclei and prominent nucleoli. At that time, the differential diagnosis revolved around lymphoid proliferation and Hodgkin’s lymphoma. Further investigations established the case as toxoplasma lymphadenitis. To the best of my knowledge, clinical follow-up was unremarkable and our colleague is doing fine till now.
In my work titled ‘Atypical lymphoid proliferations: the pathologist’s viewpoint’, I proposed the descriptive terminology of (atypical lymphoid proliferation), trying to cover the differential diagnostic problems between malignant lymphoma and reactive hyperplasia. I clearly stated this issue and attempted to define when this designation should be used and the approaches to these challenging cases. In my opinion, the atypical lymphoid proliferations are conditions in which it is not possible to differentiate between the benign and the malignant nature of a given lymphoid infiltrate.
In sum, I totally agree with the authors (Pagni et al.) that every effort should be made by the pathologist to generate a conclusive report that clearly defines the exact nature of a given lymphoid lesion. Moreover, the use of the descriptive term ‘lymphoid proliferation’ should be restricted to cases in which with full investigations (clinical, radiological, immunohistological and molecular findings) the pathologist is not able to clearly define a given lymphoid proliferation as either a reactive or neoplastic entity. I believe that the term ‘lymphoid proliferation’ reflects a state of not only incomplete disease definition but also our rudimentary biologic and immunologic understanding of these lesions. Indeed, further immunological and molecular studies will improve our understanding of these challenging conditions.
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