Atypical lymphoid proliferations: the pathologist’s viewpoint

Abstract

Lymphoid proliferations are traditionally thought to be either benign conditions (reactive hyperplasia and lymphadenitis) or malignant lymphomas. However, not all lymphoid lesions at present can be precisely placed into one of these categories. Therefore, in addition to these two extremes, there also exist a third group of lymphoid proliferations - the atypical lymphoid proliferations (AtLP). AtLP is a descriptive term used when it is not possible for the pathologist to differentiate between the benign and the malignant nature of a given lymphoid infiltrate. AtLP represent biologically indeterminate lesions that have some worrisome clinicopathologic features but cannot be interpreted as malignant lymphomas using all criteria currently available. They have some likelihood for subsequent transformation into lymphomas, and therefore AtLP occupy a middle ground between benign and malignant lymphoid proliferations. Nevertheless, sometimes AtLP are not necessarily premalignant and may very well represent a fully benign situation mimicking malignancy. In the author's opinion, when confronted with a challenging lymphoproliferative lesion, the pathologist should marshall all resources available to interpret it as precisely as possible and therefore place it into one of the two categories: unequivocally benign condition or malignant lymphomas. The resources should include immunohistochemical and molecular studies, obtaining expert opinion and rebiopsy. However, if clinical, morphologic and molecular findings are not sufficient for diagnosis of a benign condition versus lymphoma, the descriptive term AtLP can be used. In the author's opinion, the use of this descriptive term AtLP may obviate the need to force some lymphoid proliferations (equivocal lesions or mimickers of lymphomas) into either the benign or malignant categories.

Role of Immunohistochemical Tests in Early Diagnosis of T-cell Lymphoma with Primary Oral Manifestations

“…The histology of these diseases are variable. The pattern in lymph nodes is diffuse and usually appear like a mixture of small, medium and large atypical cells with pronounced polymorphism and nuclear pleomorphism [11]. Tumor cells express T-cell-associated antigens (CD2,3,5+) but usually lack CD7.…”

Rapidly Fatal Encephalitis Associated with Atypical Lymphoid Proliferations of the Basal Ganglia Subsequent to Aneurysmal Subarachnoid Hemorrhage

“…Atypical lymphoid proliferations are the result of a polyclonal immune response to antigenic stimulation. 1 The causes are often broken down into one of five categories: infectious, immunodeficiency, medicationassociated, immunosuppressive drugs, and autoimmune diseases. 6 Much of the literature surrounding central nervous system atypical lymphoproliferative diseases are found in immunocompromised patients, such as those with solid organ transplants necessitating immunosuppressant regimens with subsequent activation of the Epstein- Barr virus leading to lymphoid proliferation or hyperplasia.…”

“…Traditionally, lymphoid proliferations have been classified as benign or malignant processes, such as reactive hyperplasic or lymphoma, respectively. 1 However, there are cases where lymphoid lesions are biologically indeterminate where the tissue may exhibit histopathologic characteristics suggestive of a malignant process but cannot be diagnosed as such based upon specified criteria. In this instance, a diagnosis of atypical lymphoid proliferations may be given, which serves as a grey zone between benign and malignant lymphoid proliferations.…”

Establishment of a combination scoring method for diagnosis of ocular adnexal lymphoproliferative disease

“…RFH is considered to be a benign and reversible hyperproliferative condition that presents as a mass-like lesion characterized by many LFs with infiltration of mature plasma cells and histiocytes [6]. In contrast, ALH is an equivocal lymphoproliferative lesion that cannot be diagnosed as definitely benign or malignant and is characterized by serious clinicopathologic features that are still insufficient to justify a malignant diagnosis [7,8]. It has been suggested that ocular adnexal LPDs might arise from chronic inflammatory or autoimmune disorders [3,9–14].…”