In‐situ follicular neoplasia: a clinicopathological spectrum

Abstract

In-situ follicular neoplasia: a clinicopathological spectrum Aims: In-situ follicular neoplasia (ISFN) occurs in approximately 2-3% of reactive lymph nodes, and is currently set apart from 'partial involvement by follicular lymphoma' (PFL). ISFN can progress to overt lymphoma, but precise parameters with which to assess this risk and its association with related diseases remain incompletely understood. The aim of this study was to explore these parameters. Methods and results: We reviewed 11 cases of ISFN and one of PFL between 2003 and 2018. Ten patients had ISFN in the lymph nodes, and one had ISFN in the spleen. Haematoxylin and eosin and immunohistochemical stains were reviewed. Involvement of follicles by ISFN was scored with a three-tier scheme. Of five patients with low ISFN scores, one had chronic myelomonocytic leukaemia, one had mycosis fungoides, and three were free of haematopoietic disease. Among them, four are alive and one was lost to follow-up. Of the six ISFN patients with high scores, two had concurrent marginal zone lymphomas, one had concurrent diffuse large B-cell lymphoma (DLBCL), one had Castlemanlike disease, one had progressive transformation of germinal centres with IgG4-related disease, and one had no haematopoietic disease; all are alive except for one who died of concurrent DLBCL. The patient with PFL developed DLBCL 7 years after diagnosis. Conclusions: On the basis of this limited series, we conclude that only cases with high scores are associated with an overt lymphoma or an abnormal lymphoid process, and that scoring may be a useful parameter with which to assess the risk of associated lymphoma, and deserves further study. We also performed a comprehensive review of the literature.

The application of a multidisciplinary approach in the diagnosis of Castleman disease and Castleman‐like lymphadenopathies: A 20‐year retrospective analysis of clinical and pathological features

“…Tamber et al, by reviewing 11 cases of ISFN, described 2 cases in lymph nodes with Castleman-like disease and with IgG4-RD respectively, suggesting that ISFN may be a marker of B-cell dysfunction. 42 The fourth case was instead an HHV8-MCD in which the reactivation and clonal expansion of interfollicular EBV-infected B cells related to the CD-induced immune dysregulation was postulated. This hypothesis is in line with that suggested by Hanson et al, who found a minor IGH rearrangement in two patients with plasma cell variant of CD in whom EBV genome copies were detected in the examined lymph nodes.…”

“…Of the MCD, two cases were associated with MGUS with one meeting the criteria for POEMS, whereas one was partially involved by ISFN. Tamber et al., by reviewing 11 cases of ISFN, described 2 cases in lymph nodes with Castleman‐like disease and with IgG4‐RD respectively, suggesting that ISFN may be a marker of B‐cell dysfunction 42 . The fourth case was instead an HHV8‐MCD in which the reactivation and clonal expansion of interfollicular EBV‐infected B cells related to the CD‐induced immune dysregulation was postulated.…”

In situ follicular neoplasm discovered as an enlarging pulmonary nodule complicated by pulmonary aspergillosis

“…Therefore, pulmonary aspergillosis should be included in the differential diagnosis of the enlarged pulmonary nodules, which could explain the absence of enlarged intra‐abdominal lymph nodes. Furthermore, if ISFN had been considered in the differential diagnosis, a definite diagnosis would require resection 1 …”

“…Furthermore, if ISFN had been considered in the differential diagnosis, a definite diagnosis would require resection. 1 ISFN does not require aggressive treatment; however, careful follow-up is needed. The rate of ISFN observed in resected lymph nodes is approximately 2%-3%, and the frequency of progression to overt FL is <5%.…”

“…In situ follicular neoplasia (ISFN) is a neoplastic proliferation of follicular lymphoma‐like B cells confined to the germinal centers. Occasionally, it is detected as an incidental finding following lymph node resection for another lesion 1 . The previously described follicular lymphoma (FL) in situ has now been reclassified as ISFN according to the 2017 World Health Organization classification 1 .…”