An unusual regressive germinal center, the 'FDC-only lymphoid follicle,' in lymph nodes of organ transplant recipients

An Autopsy Case of Wiskott-Aldrich Syndrome Revealing "FDC-Only Lymphoid Follicles" in Lymphoid Tissue: A Morphologic Correlate of Defective Immune Synapse

Wiskott-Aldrich Syndrome (WAS) is an inherited disorder characterized by the classical triad of eczema, micro-thrombocytopenia, and immune deficiency. This disease affects the hematopoietic cells to a variable extent. The spectrum of clinical and laboratory data for WAS has been well described in the literature though there is a paucity of its histopathologic and immunohistochemical correlates. The current case describes the autopsy findings of this rare entity in an 8-year old male child with specific recognition of altered histology noticed in the lymphoreticular tissues. The predominant morphological finding in lymphoid tissue was atretic hyalinized germinal centers labeled as "the follicular dendritic cell (FDC)-only lymphoid follicles." Immunohistochemistry revealed a reduction in germinal-center B-cells, T-follicular helper cells, attenuated mantle zone, FDC proliferation, and paracortical plasmacytosis. This case highlights the crippled immune cell population in WAS, ultimately leading to the morphology of atretic follicles rich in FDCs.

Development, maturation and subsequent activation of follicular dendritic cells (FDC): immunohistochemical observation of human fetal and adult lymph nodes

To elucidate the processes involved in development and activation of human follicular dendritic cells (FDC), immunohistochemistry was performed on paraffin sections of fetal lymph nodes (FLN) obtained from archived autopsy material, and of adult reactive lymph nodes (ARLNs) excised for diagnostic purpose, using a panel of antibodies. Our study showed that tiny clusters of CNA.42(+ )KiM4p(+) cells, surrounded by some B-lymphocytes, initially arose in the cortical area of underdeveloped FLN around the 20th gestational week. No co-expression of CD21 and CD35 was found. In the relatively developed FLN of the same gestational age, small eddies of immature FDC, which expressed CD21, CD35, and nerve growth factor receptor (NGFR), as well as CNA.42 and KiM4p, were observed within ill-defined aggregations of B-lymphocytes. As gestation progressed, more B-lymphocytes assembled in a compact manner and formed primary lymphoid follicles containing an extending web of mature FDC, which expressed CNA.42, KiM4p, CD21, CD35, NGFR, and sometimes CD23 and X-11. In well-developed secondary follicles of ARLNs, activated FDC expressed additional molecules such as CD55, CD106, and S100alpha. Our observations identified the processes of phenotypic alteration of human FDC and established practical indicators determining their developmental stage and functional phase.

Expression of glucocorticoid receptors in non-neoplastic lymphoid follicles and B cell type malignant lymphomas

OBJECTIVE

To evaluate the expression of human glucocorticoid receptors (hGRs), such as hGR (4H2), hGR-alpha, and hGR-beta, in non-neoplastic lymphoid follicles and B cell type malignant lymphomas.

METHODS

The expression of hGRs in non-neoplastic lymphoid follicles and malignant lymphomas, including diffuse large cell lymphoma, mantle cell lymphoma, and follicular lymphoma, was examined immunohistochemically. HGR (4H2) expression was confirmed by double immunostaining of tissues and in isolated cells from tonsillar germinal centres, and by immunoelectronmicroscopy.

RESULTS

In secondary lymphoid follicles of any non-neoplastic diseases--such as chronic tonsillitis, reactive lymphadenitis, and Kimura's disease--the germinal centre cells often expressed hGR (4H2) and hGR-alpha. Double immunocytochemical staining of isolated germinal centre cells showed that the majority of hGR (4H2) positive cells were CD20 positive B cells, and that follicular dendritic cells also expressed hGR. Immunoelectronmicroscopy revealed the presence of nuclear hGR (4H2) in the binucleated follicular dendritic cells and germinal centre cells. The frequency of hGR (4H2) expression in diffuse large B cell lymphoma was higher, that in mantle cell lymphoma was lower, and that in follicular lymphoma was intermediate among the types of malignant lymphoma. The hGR (4H2) expression was less frequent in cases of grade I follicular lymphoma.

CONCLUSIONS

There are differences in hGR expression between the germinal centre and the mantle zone in non-neoplastic lymphoid follicles, and differences of hGR (4H2) expression among the types of malignant lymphoma and grades of follicular lymphoma, which probably contribute to the different steroid sensitivities.

Progressive transformation of germinal center presenting with histological features of hyaline-vascular type of Castleman's disease

We report three cases showing progressive transformation of the germinal center (PTGC) with histological features reminiscent of the hyaline-vascular (HV) variant of Castleman's disease (CD). Each case contained a few small HV germinal centers as well as PTGC and hyperplastic germinal centers with or without follicular lysis. Moreover, some of the PTGC were penetrated by hyalinized small vessels. Our three cases also showed some of the characteristic histological findings of HV type of CD: (i) reactive lymphoid follicles with small hyaline-vascular germinal centers surrounded by small lymphocytes in a concentrated fashion; (ii) a few small foci of plasmacytoid monocytes; (iii) perivascular fibrosis; (iv) interfollicular vascularity; (v) tight/concentric pattern of the follicular dendritic cell network; and (vi) absence of CD57+ T-cells in the HV follicles. The PTGC with coexistent HV type of CD may represent a certain form of reactive follicular hyperplasia. The possibility of PTGC should be considered and excluded before diagnosing CD.

Dismantling the germinal center: comparing the processes of transformation, regression, and fragmentation of the lymphoid follicle

The pathologic and immunologic features of the formation of the germinal center have been extensively studied. The process of dissolution of the germinal center is not as well understood. Different patterns of germinal-center breakdown are commonly encountered in diagnostic lymph node biopsy specimens and frequently present difficulties in diagnosis. The current immunologic understanding of germinal-center dynamics is reviewed and correlated with the histologic and immunophenotypic features of three broad classes of germinal center dissolution, namely progressive transformation, regression, and follicle fragmentation. The author suggests that these different patterns represent alternate responses to antigenic stimulation. The relationships of progressive transformation to Hodgkin's disease and of follicular regression to Castleman's disease are discussed.

Inflammatory pseudotumor-like follicular dendritic cell tumor: a distinctive low-grade malignant intra-abdominal neoplasm with consistent Epstein-Barr virus association

Follicular dendritic cell (FDC) tumors are uncommon neoplasms that can involve lymph nodes or extranodal sites. They can exhibit a broad spectrum of histologic appearances and behavior, but the intra-abdominal ones usually pursue an aggressive course. The purpose of this study was to characterize a distinctive variant of FDC tumor morphologically mimicking inflammatory pseudotumor through analysis of the clinicopathologic features of 11 cases. The patients included 10 women and one man (age range, 19-61 years; median age, 40 years) who presented with abdominal discomfort or pain. Six patients had systemic symptoms such as marked weight loss, fever, or malaise. All tumors occurred in intra-abdominal sites: liver (n = 7), spleen (n = 3), and peripancreatic region (n = 1). Of the nine patients with follow-up data, six were alive and well, one developed recurrence at 9 years, and two had repeated recurrences over many years. Grossly, the tumors were usually solitary and fleshy, punctuated by areas of hemorrhage and necrosis. Histologically, in a background of abundant lymphocytes and plasma cells were dispersed spindle or ovoid cells with vesicular nuclei and distinct nucleoli. The degree of nuclear atypia was variable, and some nuclei could be grotesque or resemble Reed-Sternberg cells. Focally, spindle cell fascicles could be formed. The atypical cells were immunoreactive for FDC markers such as CD21/CD35, CD23, and CNA.42. In situ hybridization for Epstein-Barr virus (EBV)-encoded RNA was positive in all cases, remarkably highlighting the spindle cells and their atypia. EBV-latent membrane protein-1 was expressed commonly, albeit often focally and weakly. Therefore, inflammatory pseudotumor-like FDC tumor represents a distinctive variant of FDC tumor that differs from conventional FDC tumor in the following aspects: marked female predominance; selective localization in intra-abdominal sites, especially the liver and spleen; frequent presence of systemic symptoms; indolent behavior despite an intra-abdominal location; dispersed distribution of tumor cells and prominent lymphoplasmacytic infiltration; and consistent association with EBV.

Reactive follicular hyperplasia in the lymph node lesions from systemic lupus erythematosus patients: a clinicopathological and immunohistological study of 21 cases

To clarify the clinicopathological and immunohistological findings of reactive follicular hyperplasia in systemic lupus erythematosus (SLE) lymphadenopathy, we examined 21 such cases, including four males and 17 females. Three main patterns could be delineated: pattern A, histological features of Castleman's disease (n = 6); pattern B, follicular hyperplasia with pronounced arborizing vasculature in the paracortex resembling T-zone dysplasia with hyperplastic follicles (n = 6); and pattern C, follicular hyperplasia without any other specific findings (n = 9). The patients who showed patterns A and B on histology were all female with a median age of 36 years, and presented with the lymphadenopathy within 4 months, some before a definitive diagnosis could be made. The group with pattern C included four males and five females with an age ranging from 20 to 58 years (mean, 37 years). In seven of them, the lymphadenopathy was noted 6 months or more after the therapy had been initiated. In a virological study, a small to moderate number of the lymphoid cells were positive for the Epstein-Barr virus-encoded small RNA in five of 10 cases examined. Human herpesvius 8 was not detected in the four cases examined by polymerase chain reaction and immunohistochemistry. The present study demonstrated that SLE lymphadenopathy showed histological variety and occasionally represented histopathological findings of multicentric Castleman's disease or findings similar to T-zone dysplasia with hyperplastic follicles in the biopsied specimens. We emphasize that careful attention to these morphological features, together with clinical and laboratory examinations, should allow a firm diagnosis of SLE to be made, providing information that is pertinent to the treatment of the disease. Moreover, disarray of the follicular dendritic cell (FDC) network, which could be easily detected by immunohistochemistry, was found in approximately 60% of our series. SLE lymphadenopathy should be listed as one of the diseases occasionally associated with disarray of the FDC network, although its clinicopathological significance remains unclear.