Inflammatory pseudotumor-like follicular dendritic cell tumor: a distinctive low-grade malignant intra-abdominal neoplasm with consistent Epstein-Barr virus association
ABSTRACT 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.
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ABSTRACT: Hepatic angiomyolipoma (AML) is rare. Based on its wide histomorphological range, several distinctive histological variants have been delineated. However, hepatic AML displaying predominantly or exclusively inflammatory pattern closely mimicking inflammatory pseudotumor (IPT) is exceptionally rare with only 7 cases reported so far. We herein describe a new case of hepatic inflammatory AML in a 51-year-old woman who presented with unexplained constitutional symptoms suggesting an infectious disease. A liver mass was detected during imaging examination and resected (4.3 cm in maximum diameter). The patient's symptoms resolved completely after surgery. Currently, she is alive and well 7 years after surgery. She has no evidence of other organ manifestations of IgG4-related systemic disease. The tumor displayed a pure IPT-like histological pattern with dense infiltrates of plasma cells, lymphocytes and histiocytes admixed with scattered few adipocytes, irregularly distributed thick-walled vessels (some of them showed obliterative phlebitis) as well as aggregates and fascicles of histiocytoid and spindle-shaped myoid cells that were immunoreactive for HMB45 and Melan A with focal expression of alpha smooth muscle actin. Lesional cells were negative for desmin, protein S100, CD21, CD23, CD15, CD30, HepPar-1, pankeratin (KL-1), ALK1, and EBV in situ hybridization (EBER). The surrounding liver parenchyma showed striking lymphoplasmacytic non-destructive pericholangitis. Numerous scattered and aggregated IgG4 positive plasma cells were seen within the mass and in the peritumoral inflammatory lesions (mean, 37 cells/HPF; IgG4: IgG ratio = 28%). To our knowledge, this is the first report of hepatic inflammatory AML closely resembling IgG4-related IPT of the liver. A possible role for IgG4 seems likely to explain the peculiar histological features and the unusual clinical presentation in this case.International journal of clinical and experimental pathology 01/2013; 6(4):771-9. · 1.78 Impact Factor
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ABSTRACT: The diagnosis of follicular dendritic cell (FDC) sarcoma can be challenging because of its morphologic overlaps with many other spindle cell neoplasms and, therefore, new phenotypic markers will be helpful in its differential diagnosis. Podoplanin is a mucin-type transmembrane glycoprotein that has recently been detected in reactive FDCs. In this study, we investigated the expression patterns of podoplanin using a new mouse monoclonal antibody D2-40, and compared them with CD21, a well-established FDC marker, in a comprehensive panel of cases. The panel included 4 FDC sarcomas, 38 spindle cell neoplasms of other types, 25 reactive lymphoid hyperplasia, and 117 lymphoid and 5 myeloid malignant hematopoietic neoplasms. Our study revealed that D2-40 strongly stained 3 of 4 FDC sarcomas. In contrast, D2-40 stained only 2/38 other spindle cell neoplasms tested. Furthermore, we observed that D2-40 highlighted more FDC meshworks than CD21 in Castleman's disease, follicular lymphoma, nodular lymphocyte predominance Hodgkin lymphoma, and residual reactive germinal centers in a variety of lymphoma types. D2-40 and CD21 stained an equal number of cases of reactive lymphoid hyperplasia, progressively transformed germinal centers and angioimmunoblastic T-cell lymphoma. No expression of podoplanin was detected in normal or neoplastic lymphoid and myeloid cells. We conclude that podoplanin (D2-40) is a sensitive and specific FDC marker, which is superior or equal to CD21 in evaluating both reactive and neoplastic FDCs. In addition, our results suggest that podoplanin (D2-40) can be used to support the diagnosis of FDC sarcoma.International journal of clinical and experimental pathology 02/2008; 1(3):276-84. · 1.78 Impact Factor
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ABSTRACT: Inflammatory myofibroblastic tumor (IMT) is an uncommon mesenchymal neoplasm with a variable histologic appearance that may mimic other spindle cell processes, particularly nodular fasciitis, desmoid tumor, and in intra-abdominal locations, gastrointestinal stromal tumor. Recently, gene fusions involving ALK at chromosome 2p23 have been described in IMTs. The resultant ALK protein overexpression in the myofibroblastic component of these tumors is detectable by immunohistochemistry. We examined 73 IMTs, 20 cases of nodular fasciitis, 15 desmoid fibromatoses, and 15 gastrointestinal stromal tumors by immunohistochemistry using ALK-11, a rabbit polyclonal antibody that recognizes the C-terminus of the protein. ALK positivity was detected in 44 of 73 (60%) IMTs. All cases of nodular fasciitis, desmoid fibromatosis, and gastrointestinal stromal tumors were ALK negative (p < 0.001). These findings demonstrate that ALK positivity is common in IMTs, and immunohistochemistry using anti-ALK antibodies can be helpful in the differential diagnosis of these neoplasms. In addition, anti-ALK staining seems to correlate with those IMTs that have the typical tri-patterned histologic appearance and clinical presentation, providing additional support to the premise that IMT is a distinctive clinicopathologic entity within the broad category of inflammatory pseudotumors.American Journal of Surgical Pathology 12/2001; 25(11):1364-71. DOI:10.1097/00000478-200111000-00003 · 4.59 Impact Factor