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.
Available from: Konstantinos Vardas
- "This benign lesion needs to be distinguished from an inflammatory pseudotumor-like follicular dendritic cell (IPT-like FDC) tumor, a distinctive low-grade malignant neoplasm with consistent Epstein-Barr virus (EBV) association that has a similar morphology . The IPT-like variant of FDC tumor is usually found in the spleen or liver and appears to be much more indolent compared to conventional FDC sarcoma . Splenic IPT-like FDC tumors are extremely rare lesions, and only a few cases have been previously reported. "
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ABSTRACT: Inflammatory pseudotumor of the spleen with expression of follicular dendritic cell markers is an extremely rare lesion with only a few cases reported previously. The present study reports on an inflammatory pseudotumor of the spleen 10 × 8 × 7 cm in size that was incidentally found in a 61-year-old man and increased gradually in size during a period of 3 months. Abdominal ultrasonography revealed a well-circumscribed splenic mass, and abdominal computed tomography confirmed the presence of a well-circumscribed isodense lesion in the splenic hilum with inhomogenous enhancement in the early-phase images and no enhancement on delayed-phase contrast-enhanced images. Magnetic resonance imaging of the abdomen showed a well-defined isodense tumor on T1-weighted images with mildly increased signal intensity on T2-weighted images, and this is only the second study that provides MRI findings of this entity. The patient underwent an uncomplicated open splenectomy for definitive histologic diagnosis. Under microscopic examination, the lesion was an admixture of lymphocytes, plasma cells and spindle cells. In situ hybridization analysis for Epstein-Barr virus (EBV) revealed that most of the spindle cells were positive for EBV, and immunochemistry showed the expression of the follicular dendritic cell markers CD21, CD35 and CD23 within the tumor. The diagnosis of inflammatory pseudotumor-like follicular dendritic cell tumor was established.
- "Cheuk et al.3 reported the largest series of IPT-like FDC sarcoma, with all 11 cases occurring in the abdominal cavity and with overrepresentation of female patients and hepatosplenic involvement.3 Furthermore, all tumors in the series were positive for Epstein-Barr virus (EBV) by in situ hybridization. "
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ABSTRACT: Follicular dendritic cell (FDC) sarcoma is rare and is classified either as conventional type or inflammatory pseudotumor (IPT)-like variant. Extranodal presentation is uncommon and nearly all gastrointestinal FDC tumors are of the conventional type. IPT-like variant tumors occur almost exclusively in the liver and spleen and are consistently associated with Epstein-Barr virus (EBV). Here we report the case of a 78-year-old woman with an IPT-like FDC sarcoma presenting as a pedunculated colonic polyp. Histologically, scanty atypical ovoid to spindle cells were mixed with a background of florid lymphoplasmacytic infiltrate, which led to an initial misdiagnosis of pseudolymphoma. These atypical cells expressed CD21, CD23, CD35, and D2-40, and were positive for EBV by in situ hybridization, confirming the diagnosis. The patient was free of disease five months after polypectomy without adjuvant therapy. Although extremely rare, the differential diagnosis for colonic polyp should include FDC sarcoma to avoid an erroneous diagnosis. A review of the 24 cases of IPT-like FDC sarcoma reported in the literature reveal that this tumor occurs predominantly in females with a predilection for liver and spleen, and has a strong association with EBV.
Available from: PubMed Central
- "The etiology and pathogenesis of FDCS are not clear. It is possible that certain FDCSs, particularly in hepatic and splenic lesions (10–12), are associated with EBV infection, although the association is not evident in pharyngeal tumors as the in situ hybridizations for EBV-encoded RNA were negative in the study by Duan et al(8), as well as the present study. Pauwels et al(13) and Chan et al(14) agreed that FDCS developed according to a hyperplasia-dysplasia-neoplasia sequence in follicular dendritic cells. "
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ABSTRACT: Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm arising most commonly from follicular dendritic cells in the lymph nodes. It is exceedingly rare in extranodal sites, particularly in the pharyngeal region. The present study reports 3 cases occurring in the pharyngeal region. Case 1 had tonsil and cervical lymph node involvement, while case 3 also had tonsil involvement. Cases 1 and 3 relapsed locally at 3 and 17 months after surgery, respectively. Case 2 was diagnosed with a tumor in the parapharyngeal space and the patient succumbed to the disease 5 months after treatment with combined surgery and chemotherapy. All 3 cases were misdiagnosed initially. Pathological biopsy examination, including histopathology and immunohistochemistry, was essential for diagnosis. The data for 52 cases, including cases from the literature and the present cases, were analyzed. The results indicated that 57% (26/46) of the initial diagnoses were inaccurate, while the recurrence, metastasis and mortality rates were 40, 16 and 10%, respectively. The statistics supported the theory that FDCS of the pharyngeal region is a low-grade sarcoma. Involvement of the tonsils (52%, 27/52) and parapharyngeal space (19%, 10/52) were observed most commonly, while FDCS at various sites showed different prognoses. The various survival rates were calculated in the present study. The large tumors (≥4 cm) had a poorer prognosis than the small tumors (<4 cm; P<0.05). Among the 50 cases with available follow-up data, 46% (23/50) were treated with surgery alone, 52% (26/50) with combination therapy (surgery followed by chemotherapy and/or radiotherapy) and 2% (1/50) with surveillance. There was no statistically significant evidence (P>0.05) that combination therapy improves survival rates, compared with surgery alone.
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