Nodular lymphocyte predominant HL is a neoplasm of germinal center B-cells that displays a growth pattern that is at least partially nodular. Whether an entirely diffuse form of LPHL exists has been controversial, and most cases formerly reported as diffuse LPHL are currently thought to represent either T-cell rich large B-cell lymphomas or LRCHL.19 Overall, nLPHL represents approximately 5% of all cases of HL.

An intriguing association between nLPHL and a form of benign hyperplasia known as progressive transformation of germinal centers (PTGC) has led to the suggestion that PTGC may represent a precursor lesion for nLPHL.36 PTGC may be seen within the same lymph node containing nLPHL, or PTGC may be found in biopsies without evidence of malignancy obtained either before or after the diagnosis of nLPHL. It should be noted, however, that most patients with PTGC do not go on to develop nLPHL.37

A small subset of patients, approximately 3-5%,19 will go on to develop a large B-cell lymphoma. Many of these cases display the morphologic features of T-cell rich large B-cell lymphoma (TCRLBL). In fact, although the clinical features of nLPHL and TCRLBL are quite distinct, it can be difficult in some cases to distinguish between these two entities based on morphologic and immunophenotypic findings.

Figure 71.5 Nodular lymphocyte predominant Hodgkin's lymphoma. A nodular proliferation of lymphocytes and his-tiocytes is present

Recognition of such cases with features overlapping nLPHL and TCRLBL has led to the suggestion that these two neoplasms may be biologically related.3839

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