Morphologic variant of follicular lymphoma reminiscent of hyaline-vascular Castleman disease

Unicentric Castleman Disease: Illustration of Its Morphologic Spectrum and Review of the Differential Diagnosis

CONTEXT.—

Unicentric Castleman disease (UCD) is a dynamic entity with a wide spectrum of morphologic findings. UCD can be further subdivided into hyaline-vascular and mixed/plasmacytic variants. Hyaline-vascular UCD has both follicular and interfollicular (stromal) changes, and occasionally these lesions show a skewed representation of either the follicular or stromal compartments. Plasmacytosis is usually minimal in the hyaline-vascular variant. The mixed/plasmacytic variant of UCD is composed of sheets of plasma cells often associated with a variable number of follicles with regressive changes.

OBJECTIVE.—

To illustrate the differential diagnosis of UCD, as it is quite broad and includes lymphomas, plasma cell neoplasms, stromal neoplasms such as follicular dendritic cell sarcoma and vascular neoplasms, immunoglobulin G4-related disease, infections, and other rare lesions. An additional objective is to enhance awareness of the morphologic features of UCD in excisional and in small core-needle biopsy specimens, the latter of which may inadvertently target follicle- or stroma-rich areas, causing diagnostic challenges.

DATA SOURCES.—

In this review, we provide readers a concise illustration of the morphologic spectrum of UCD that we have encountered in our practice and a brief discussion of entities in the differential diagnosis.

CONCLUSIONS.—

UCD exhibits a broad spectrum of morphologic changes, and awareness of these morphologic variations is key to avoid misdiagnosis.

Analysis of immunophenotypic features in hyaline vascular type Castleman disease

BACKGROUND

Studies suggested that the immunophenotype of hyaline vascular type Castleman disease (HVCD) lacked characteristics, which was easy to be confused with other diseases.

METHODS

From January 2010 to June 2022, 17 cases of HVCD were selected from the Department of Pathology of Shaanxi Provincial People's Hospital and the Department of Pathology of Shaanxi Provincial Cancer Hospital. 13 cases of reactive hyperplastic lymph nodes (RHL) and 11 cases of follicular lymphoma (FL) were selected as the control group. All cases were performed CD3, CD20, CD21 and BCL2 immunohistochemical staining.

RESULTS

(i) In 17 cases of HVCD, the negative area of BCL2 of germinal center was significantly smaller than the negative area of CD3 of germinal center. However, in 13 cases of RHL, the negative area of CD3 of germinal center was basically consistent with the negative area of germinal center of BCL2 of germinal center. In 11 cases of FL, in neoplastic follicles, the negative area of CD3 was basically consistent with the positive area of BCL2. The difference between HVCD group and other two groups of diseases was statistically significant (P < 0.05). (ii) In 17 cases of HVCD, the negative area of BCL2 of germinal center was significantly smaller than the follicular dendritic cell (FDC) meshworks expressed by CD21. However, in 13 cases of RHL, the FDC meshworks expressed by CD21 were basically consistent with the negative area of BCL2 of germinal center. In 11 cases of FL, in neoplastic follicles, the FDC meshworks expressed by CD21 was basically consistent with the positive area of BCL2. The difference between HVCD group and other two groups of disease was statistically significant (P < 0.05).

CONCLUSIONS

HVCD has unique immunophenotypic characteristics. The negative area of BCL2 of germinal center is significantly smaller than the negative area of CD3. The negative area of the BCL2 of germinal center is significantly smaller than the FDC meshworks expressed by CD21. These two immunophenotypic features in HVCD are very important in diagnosis and differential diagnosis.

In situ follicular neoplasia: a clinicopathologic spectrum

AIMS

In situ follicular neoplasia (ISFN) occurs in ≈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 to assess this risk and its association with related diseases remain incompletely understood. This study proposes to explore these parameters.

METHODS AND RESULTS

We reviewed 11 cases of ISFN and 1 of PFL between 2003 and 2018. Ten patients had ISFN in lymph nodes, one in the spleen. H&E and immunohistochemical stains were reviewed. Involvement of follicles by ISFN was scored using a 3-tier scheme. Of 5 cases with low ISFN scores, one had chronic myelomonocytic leukemia, one mycosis fungoides and three were free of hematopoietic diseases. Among them, 4 are alive and one was lost to follow-up. Of the 6 ISFN cases with high scores, 2 had concurrent marginal zone lymphomas, 1 concurrent diffuse large B-cell lymphoma (DLBCL), 1 Castleman-like disease, another progressive transformation of germinal centers with IgG4-related disease, and 1 no hematopoietic disease; all are alive except one who died of concurrent DLBCL. The patient with PFL developed DLBCL 7 years after diagnosis.

CONCLUSIONS

Based on 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 to assess risk for associated lymphoma, deserving further study. We also carried out a comprehensive review of the literature.