Follicular dendritic cell sarcoma of the spleen

Epstein-barr virus (EBV)-positive inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) presenting as thrombocytopenia: A case report and literature review

Background

Follicular dendritic cell sarcoma (FDCS) represents an exceedingly rare malignant neoplasm. Inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) is recognized as a variant manifestation of FDCS. The clinical incidence of this particular disease is remarkably low, resulting in the absence of established standardized clinical protocols for its management and treatment.

Methods

Presented here is a case of primary Epstein-Barr virus (EBV)-positive splenic IPT-like FDCS, noteworthy for manifesting thrombocytopenia as its initial symptom. Our study analyzed the clinicopathologic characteristics of this case and 29 previously reported cases identified in the literature. Also, we conducted a comprehensive review of pertinent literature.

Results

We administered splenectomy to this patient and verified the diagnosis of EBV-positive IPT-like FDCS through immunohistochemical examination. Postoperatively, the patient underwent a one-year follow-up period, demonstrating no signs of recurrence. Analyzing a total of 30 cases revealed that this disease is more prevalent in female patients (F:M = 1.14:1), with a median age of 62 years. Fifteen patients were asymptomatic, and nine patients presented with abdominal discomfort or pain. All patients underwent surgical treatment. Among the cases, histopathological and immunohistochemical information was unavailable for five; however, in the remaining 25 cases, histopathology revealed a distinct inflammatory cell infiltration and spindle tumor cells arranged in sheets or fascicles. These tumor cells had vesicular chromatin and distinct nucleoli and they expressed conventional FDC markers. In situ hybridization analysis of Epstein-Barr virus-encoded small RNA (EBER) showed that all 30 cases were EBV-positive. Follow-up information showed that no patients relapsed and one (3.8 %) patient died.

Conclusion

The clinical diagnosis of EBV-positive IPT-like FDCS poses considerable challenges, necessitating a conclusive diagnosis through pathological immunohistochemical examination. EBER in situ hybridization holds significance for the definitive diagnosis of the disease. We advocate for splenectomy as the treatment of choice for limited splenic IPT-like FDCS.

Controversies in the Spleen: Histiocytic, Dendritic, and Stromal Cell Lesions

Histiocytic, dendritic, and stromal cell lesions that occur in the spleen are challenging diagnostically, not well studied due to their rarity, and therefore somewhat controversial. New techniques for obtaining tissue samples also create challenges as splenectomy is no longer common and needle biopsy does not afford the same opportunity for examination of tissue. Characteristic primary splenic histiocytic, dendritic, and stromal cell lesions are presented in this paper with new molecular genetic findings in some entities that help differentiate these lesions from those occurring in non-splenic sites, such as soft tissue, and identify possible molecular markers for diagnosis.

Follicular dendritic cell sarcoma

Follicular dendritic cells (FDC) are mesenchymal-derived dendritic cells located in B-follicles where they play a pivotal role in triggering and maintaining B-cell adaptive immune response. In 1986 Dr. Juan Rosai first reported a series of neoplasms showing features of FDC and defined it as Follicular Dendritic Cell Tumor, subsequently renamed as "sarcoma" (FDCS). In its seminal and subsequent articles Rosai and colleagues highlighted the heterogeneous microscopic appearance of FDCS and its immunohistochemical and ultrastructural features.

FDCS mostly occurs in extranodal sites (79.4% of cases) and lymph nodes (15.1%); in about 7%-10% of cases it is associated with hyaline-vascular Castleman disease. Given its significant growth pattern and cytological variability, FDCS can be confused with various neoplasms and even inflammatory processes. The diagnosis requires the use of a broad spectrum of FDC markers (e.g. CD21, CD23, CD35, clusterin, CXCL13, podoplanin), particularly considering that tumor antigen-loss is frequent. The inflammatory-pseudotumor-like (IPT-like) variant of FDCS, in addition to its peculiar histopathological and clinical features, is characterized by positivity of tumor cells for Epstein-Barr virus, representing a diagnostic requisite.

No distinctive genetic and molecular anomalies have been identified in FDCS. It often carries an aberrant clonal karyotype and chromosomal structural alterations, frequently involving onco-suppressor genes. Direct or next generation sequencing showed alterations on genes belonging to the NF-κB regulatory pathway and cell-cycle regulators. In contrast to hematopoietic-derived histiocytic and dendritic cells tumors, FDCS typically lacks mutations in genes related to the MAPK pathway.

FDCS recurs locally in 28% and metastasizes in 27% of cases. Extent of the disease, surgical resectability and histopathological features are significantly associated with the outcome. IPT-like FDCS behaves as an indolent tumor, even if it often recurs locally over years.

Complete surgical excision is the gold standard of treatment. Data on targeted therapies (e.g.: tyrosine kinase inhibitors) or immune checkpoint inhibitors are very limited and responses are variable. A better understanding of the molecular drivers of this tumor may lead to potential new therapeutic strategies.

Spinal Cord Compression Caused by Fibroblastic Reticular Cell Tumor (FRCT) Originating from Thoracic Spine

BACKGROUND

The authors present the first reported case of a fibroblastic reticular cell tumor (FRCT) presenting with spinal cord compression. FRCTs are the rarest subset of dendritic cell tumors, a specific group of hematologic malignancies. FRCTs reportedly behave similar to low-grade sarcomas as opposed to malignant tumors.

CASE DESCRIPTION

A 45-year-old female patient presented with a 2-and-a-half week history of a flu-like illness and 1 week history of lower limb imbalance. Magnetic resonance imaging revealed an extradural lesion at T3/4 compressing the spinal cord. Initially, the patient was presumed to have metastatic spinal cord compression, and she underwent a decompressive thoracic laminectomy with debulking of the lesion with follow-up adjuvant radiotherapy. However, histology identified a unique primary FRCT originating from spine, not secondary metastatic spinal cord compression. There were no histologically aggressive features likely contributing to the favorable outcome following surgery and adjuvant radiotherapy. Her postoperative recovery was unremarkable, and she recovered fully.

CONCLUSIONS

Although rare, we report the first case of FRCT originating in the spine causing spinal cord compression. The clinical presentation of the case, histologic features of FRCT, and the treatment options are reviewed.

Follicular Dendritic Cell Sarcoma With Indolent T-Lymphoblastic Proliferation Is Associated With Paraneoplastic Autoimmune Multiorgan Syndrome

Nonclonal expansions of immature T cells outside of the thymus, termed indolent T-lymphoblastic proliferation (iT-LBP), have been identified in rare lymphoproliferative disorders. We report that iT-LBP is a frequent finding in cases of follicular dendritic cell sarcoma (FDCS), and shows an association with paraneoplastic autoimmune multiorgan syndrome (PAMS). We studied 31 cases of FDCS by paraffin immunohistochemistry using antibodies to CD21, CD23, CD35, clusterin, CXCL13, podoplanin, CD3, CD4, CD8, CD20, CD1a, and TdT. Chart review was performed to characterize the clinical behavior including evidence of autoimmune disease. FDCS occurred in a wide variety of nodal and extranodal sites. Fourteen of 31 (45%) cases contained immature TdT-positive T cells; in 5 cases these cells were numerous and present throughout the tumor. Four of these 5 patients with numerous immature T cells developed autoimmune disease, clinically categorized as PAMS and/or myasthenia gravis. PAMS persisted after tumor resection, causing severe morbidity and mortality. These findings suggest that the neoplastic follicular dendritic cells can recruit or foster the proliferation of immature T cells and that these cells may play a role in mediating PAMS. Recognition of iT-LBP in FDCS is important to avoid misdiagnosis as thymoma or T-lymphoblastic lymphoma, and may predict serious autoimmune complications in some patients.

Practical Applications in Immunohistochemistry: An Immunophenotypic Approach to the Spleen

CONTEXT.—

Even though immunohistochemistry is routinely used by pathologists, evaluation of immunohistochemistry in splenic lesions remains difficult for many. Classification of benign and splenic lesions often requires a combination of hematoxylin-eosin evaluation, immunophenotyping, and sometimes molecular testing. Immunohistochemical staining is essential in evaluating many splenic lesions, and requires an understanding of the normal compartments of the spleen.

OBJECTIVE.—

To address different immunohistochemical features used for identification and subclassification of different lesions of the spleen, as well as in the normal compartments of the spleen.

DATA SOURCES.—

The information outlined in this review article is based on our experiences with a variety of spleen cases, on the current World Health Organization classification of hematopoietic and lymphoid tumors, and on a review of English-language articles published during 2018.

CONCLUSIONS.—

Features for phenotyping normal spleen as well as a variety of splenic lesions, including littoral cell angioma and splenic marginal zone lymphoma, are discussed. Suggested immunopanels are provided to assist in the diagnosis of different lesions of the spleen.

Canine Cancer Genomics: Lessons for Canine and Human Health

Dogs are second only to humans in medical surveillance and preventative health care, leading to a recent perception of increased cancer incidence. Scientific priorities in veterinary oncology have thus shifted, with a demand for cancer genetic screens, better diagnostics, and more effective therapies. Most dog breeds came into existence within the last 300 years, and many are derived from small numbers of founders. Each has undergone strong artificial selection, in which dog fanciers selected for many traits, including body size, fur type, color, skull shape, and behavior, to create novel breeds. The adoption of the breed barrier rule-no dog may become a registered member of a breed unless both its dam and its sire are registered members-ensures a relatively closed genetic pool within each breed. As a result, there is strong phenotypic homogeneity within breeds but extraordinary phenotypic variation between breeds. One consequence of this is the high level of breed-associated genetic disease. We and others have taken advantage of this to identify genes for a large number of canine maladies for which mouse models do not exist, particularly with regard to cancer.

Inflammatory Pseudotumor-Like Follicular Dendritic Cell Sarcoma of the Spleen: Computed Tomography Imaging Characteristics in 5 Patients

OBJECTIVES

The purpose of this study was to retrospectively review the computed tomography (CT) and clinicopathological characteristics of inflammatory pseudotumor (IPT)-like follicular dendritic cell sarcoma (FDCS) of the spleen in 5 patients.

METHODS

Clinical, pathologic, and CT imaging findings of 5 patients with IPT-like FDCS of the spleen were reviewed and analyzed. Computed tomography imaging and pathologic features were compared.

RESULTS

Abdominal unenhanced CT revealed a well-defined hypodense mass in the spleen with complex internal architecture with focal necrosis and/or speckle-strip calcification. On postcontrast CT, slightly delayed enhancement was observed in 5 cases. Four patients had a normalized spleen. The fourth patient had lung metastasis. The fifth patient had 2 relatively small lesions as well as metastases to the spine.

CONCLUSIONS

Computed tomography imaging features of IPT-like FDCS of the spleen are distinctly different from other hypovascular splenic neoplasm; however, the definitive diagnosis requires further confirmation with needle biopsy or surgery. Inflammatory pseudotumor-like FDCS of the spleen should be suggested by using the CT imaging features of the splenic mass with evidence of metastatic disease.

Targeted genomic sequencing of follicular dendritic cell sarcoma reveals recurrent alterations in NF-κB regulatory genes

Follicular dendritic cell sarcoma is a rare mesenchymal neoplasm with a variable and unpredictable clinical course. The genetic alterations that drive tumorigenesis in follicular dendritic cell sarcoma are largely unknown. One recent study performed BRAF sequencing and found V600E mutations in 5 of 27 (19%) cases. No other recurrent genetic alterations have been reported. The aim of the present study was to identify somatic alterations in follicular dendritic cell sarcoma by targeted sequencing of a panel of 309 known cancer-associated genes. DNA was isolated from formalin-fixed paraffin-embedded tissue from 13 cases of follicular dendritic cell sarcoma and submitted for hybrid capture-based enrichment and massively parallel sequencing with the Illumina HiSeq 2500 platform. Recurrent loss-of-function alterations were observed in tumor suppressor genes involved in the negative regulation of NF-κB activation (5 of 13 cases, 38%) and cell cycle progression (4 of 13 cases, 31%). Loss-of-function alterations in the NF-κB regulatory pathway included three cases with frameshift mutations in NFKBIA and two cases with bi-allelic loss of CYLD. Both cases with CYLD loss were metastases and carried concurrent alterations in at least one cell cycle regulatory gene. Alterations in cell cycle regulatory genes included two cases with bi-allelic loss of CDKN2A, one case with bi-allelic loss of RB1, and one case with a nonsense mutation in RB1. Last, focal copy-number gain of chromosome 9p24 including the genes CD274 (PD-L1) and PDCD1LG2 (PD-L2) was noted in three cases, which represents a well-described mechanism of immune evasion in cancer. These findings provide the first insight into the unique genomic landscape of follicular dendritic cell sarcoma and suggest shared mechanisms of tumorigenesis with a subset of other tumor types, notably B-cell lymphomas.

Follicular Dendritic Cell Sarcoma: Cytogenetics and pathological findings

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm with a non-specific and insidious presentation further complicated by the difficult diagnostic and therapeutic assessment. It has a low to intermediate risk of recurrence and metastasis. Unlike other soft tissue sarcomas or histiocytic and dendritic cell neoplasms, cytogenetic studies are very limited in FDCS cases. Although no specific chromosomal marker has yet been established, complex aberrations and different ploidy types have been documented. We report the case of a 39-year-old woman with FDCS who presented to the Sultan Qaboos University Hospital in Muscat, Oman, in February 2013. Ultrastructural, immunophenotypical and histological findings are reported. In addition, karyotypic findings showed deletions of the chromosomes 1p, 3q, 6q, 7q, 8q and 11q. To the best of the authors' knowledge, these have not been reported previously in this tumour. Techniques such as spectral karyotyping may help to better characterise chromosomal abnormalities in this type of tumour.

Dendritic cell and histiocytic neoplasms: biology, diagnosis, and treatment

BACKGROUND

Dendritic and histiocytic cell neoplasms are rare malignancies that make up less than 1% of all neoplasms arising in lymph nodes or soft tissues. These disorders have distinctive disease biology, clinical presentations, pathology, and unique treatment options. Morphology and immunohistochemistry evaluation by a hematopathologist remains key for differentiating between these neoplasms. In this review, we describe tumor biology, clinical features, pathology, and treatment of follicular dendritic cell sarcoma, interdigitating dendritic cell sarcoma, indeterminate dendritic cell sarcoma, histiocytic sarcoma, fibroblastic reticular cell tumors, and disseminated juvenile xanthogranuloma.

METHODS

A literature search for articles published between 1990 and 2013 was undertaken. Articles are reviewed and salient findings are systematically described.

RESULTS

Patients with dendritic cell and histiocytic neoplasms have distinct but variable clinical presentations; however, because many tumors have recently been recognized, their true incidence is uncertain. Although the clinical features can present in many organs, most occur in the lymph nodes or skin. Most cases are unifocal and solitary presentations have good prognoses with surgical resection. The role of adjuvant therapy in these disorders remains unclear. In cases with disseminated disease, prognosis is poor and data on treatment options are limited, although chemotherapy and referral to a tertiary care center should be considered. Excisional biopsy is the preferred method of specimen collection for tissue diagnosis, and immunohistochemistry is the most important diagnostic method for differentiating these disorders from other entities.

CONCLUSIONS

Dendritic cell and histiocytic cell neoplasms are rare hematological disorders with variable clinical presentations and prognoses. Immunohistochemistry remains important for diagnosis. Larger pooled analyses or clinical trials are needed to better understand optimal treatment options in these rare disorders. Whenever possible, patients should be referred to a tertiary care center for disease management.

Inflammatory Pseudotumor-like Follicular Dendritic Cell Tumor of the Spleen: Case Report and Review of the Literature

A 74-year-old woman underwent contrast-enhanced (CE) computed tomography (CT) that revealed an enlarging splenic lesion. This splenic tumor was suspected as metastasis because the patient had been diagnosed with right breast cancer with lung and right axillary lymph node metastases 4 years earlier and had undergone surgery and hormone therapy at another hospital. T2-weighted imaging of magnetic resonance (MR) imaging demonstrated the tumor with slightly high intensity with a rim of low intensity at the margin. On dynamic contrast-enhanced (DCE)-MR imaging after intravenous administration of gadolinium diethylenetriamine pentaacetic acid, delayed enhancement was observed in the center and margin of the tumor. On positron emission tomography with 2-deoxy-2-[18F] fluoro-D-glucose (FDG) integrated with CT, the tumor showed high FDG uptake. Splenic metastasis was considered based on the imaging findings, lack of inflammation on laboratory data, and clinical course, so she underwent splenectomy. Histopathologically, the tumor was encapsulated by a fibrous structure, which was depicted as the rim at the tumor margin on T2-weighted imaging and DCE-MR imaging. Immunohistochemical study allowed the diagnosis of inflammatory pseudotumor (IPT)-like follicular dendritic cell tumor (FDCT). FDCT is a primary neoplasm of lymph nodes that shows features of follicular dendritic cell differentiation, and it is rare at the spleen. Differential diagnosis is difficult between IPT-like FDCT and similar splenic tumors, such as IPT, splenic metastases, hamartoma and hemangioma. However, in addition to the enhancement pattern within a tumor on DCE-MR imaging, detection of the capsular-like rim on MR imaging might aid the diagnosis of splenic IPT-like FDCT.

Intraperitoneal follicular dendritic cell sarcoma: role of chemotherapy and bone marrow allotransplantation in locally advanced disease?

We describe a case of a 44 year-old woman diagnosed with follicular dendritic cell sarcoma (FDCS). FDCS is a very rare disease affecting the dendritic antigen presenting cells and is often misdiagnosed. Surgery is considered the best treatment modality, followed by chemotherapy. In our case, surgical excision was not possible, therefore the patient received two lines of chemotherapy followed by bone marrow allotransplantation, then a third line of chemotherapy with a complete metabolic response seen on PET/computed tomography (CT) follow-up 29 months later. A review of the literature has been performed.

Extranodal follicular dendritic cell sarcoma: A clinicopathological report of four cases and a literature review

The aim of the present study was to characterize the clinicopathological features of follicular dendritic cell sarcoma (FDCS), and to report the experience of the Xin Hua Hospital Affiliated to Shanghai Jiaotong University School of Medicine (Shanghai, China) with this entity. The clinicopathological findings of four cases that had recently been encountered and 142 previously reported cases in the English literature were evaluated. The current tumors were found in two male and two female patients, aged 49–76 years old, who exhibited a mean tumor size of 8.7 cm. Three of the four cases were misdiagnosed during the initial diagnosis and one experienced intra-abdominal recurrence six months after the first diagnosis. Assessment of all 142 cases in the literature revealed a mild female predominance. The tumors exhibited a mean tumor size of ~7.0 cm. Histologically, the tumors were composed of plump spindle- or oval-shaped cells that exhibited eosinophilic cytoplasm and were arranged in sheets, storiform patterns or whorls. Immunohistochemically, the neoplastic cells expressed at least one of the FDC markers. Among the 130 cases with follow-up data, the overall recurrence, metastasis and mortality rates were 49.2% (64 cases), 21.5% (28 cases), and 13.8% (18 cases), respectively. FDCS can appear deceptively similar to other soft-tissue tumors, even poorly-differentiated carcinomas. A correct diagnosis requires a high degree of suspicion and immunohistochemical evaluation.

A 46-year-old Chinese woman presenting with retroperitoneal follicular dendritic cell sarcoma: a case report

Introduction

Follicular dendritic cells are non-phagocytic, non-lymphoid cells of the immune system that are necessary for antigen presentation and the regulation of reactions in the germinal centers of the lymph nodes. Follicular dendritic cell sarcoma is an unusual cancer, particularly in the intra-abdominal region. In the present report we describe an unusual case of retroperitoneal follicular dendritic cell sarcoma that emphasizes the difficulty of diagnosing and treating this tumor. Retroperitoneal follicular dendritic cell sarcoma has only been rarely reported in the literature to date.

Case presentation

A 46-year-old Chinese woman of Han ethnicity presented with chronic right lower quadrant abdominal pain over the preceding 4 weeks. The tumor was resected and submitted to histopathological examination. The case was verified as retroperitoneal follicular dendritic cell sarcoma by microscopic examination and immunohistochemical analysis. After diagnosis, she received postoperative radiotherapy and chemotherapy. She has survived 3 years postoperatively, although she has a pulmonary metastasis.

Conclusions

Retroperitoneal follicular dendritic cell sarcoma may demonstrate aggressive potential. This study indicated that postoperative adjuvant radiotherapy and chemotherapy could extend the survival of a patient with retroperitoneal follicular dendritic cell sarcoma.

Ligand-dependent activation of EGFR in follicular dendritic cells sarcoma is sustained by local production of cognate ligands

PURPOSE

The aim of this study was to investigate the biological and clinical significance of epidermal growth factor receptor (EGFR) signaling pathway in follicular dendritic cell sarcoma (FDC-S).

EXPERIMENTAL DESIGN

Expression of EGFR and cognate ligands as well as activation of EGFR signaling components was assessed in clinical samples and in a primary FDC-S short-term culture (referred as FDC-AM09). Biological effects of the EGFR antagonists cetuximab and panitumumab and the MEK inhibitor UO126 on FDC-S cells were determined in vitro on FDC-AM09. Direct sequencing of KRAS, BRAF, and PI3KCA was conducted on tumor DNA.

RESULTS

We found a strong EGFR expression on dysplastic and neoplastic FDCs. On FDC-AM09, we could show that engagement of surface EGFR by cognate ligands drives the survival and proliferation of FDC-S cells, by signaling to the nucleus mainly via MAPK and STAT pathways. Among EGFR ligands, heparin-binding EGF-like growth factor, TGF-α and Betacellulin (BTC) are produced in the tumor microenvironment of FDC-S at RNA level. By extending this finding at protein level we found that BTC is abundantly produced by FDC-S cells and surrounding stromal cells. Finally, direct sequencing of tumor-derived genomic DNA showed that mutations in KRAS, NRAS, BRAF, and PI3KCA, which predicts resistance to anti-EGFR MoAb in other cancer models, are not observed in FDC-S.

CONCLUSION

Activation of EGFR by cognate ligands produced in the tumor microenvironment sustain viability and proliferation of FDC-S indicating that the receptor blockade might be clinically relevant in this neoplasm.

Dendritic cell sarcoma: a pooled analysis including 462 cases with presentation of our case series

Dendritic cell tumors are extremely rare and current knowledge on these tumors is limited. The characteristics of three dendritic cell sarcoma subtypes and their optimal treatment approaches are not fully clarified. We aimed to make a systematic review of the literature and enrich the current data with five new cases. Pooled analysis of 462 reported cases revealed that the tumor had no age, gender or racial predilection. Our analysis suggests that the young age, advanced stage, intraabdominal involvement and unfavorable histological features (i.e. large tumor size, absence of lymphoplasmacytic infiltration, coagulative necrosis, high mitotic count) may predict poor prognosis. Subtypes of this tumor have different clinical behaviors with interdigitating dendritic cell sarcoma being the most aggressive form. In general, surgery is the most effective treatment modality and adjuvant radiotherapy has no significant effect on overall survival of patients. The role of chemotherapy for the management of advanced disease is controversial.

Ovarian serous carcinoma associated with a distinct "corded and hyalinized" pattern

The "corded and hyalinized" pattern, described in endometrioid carcinoma, has not been previously reported in association with serous carcinoma. We describe a unique case of serous neoplasm of low malignant potential with low-grade serous carcinoma combined with a distinct pattern of high-grade carcinoma characterized by cords of epithelioid and spindled cells enmeshed in a hyalinized, collagenous stroma. This pattern was the predominant architecture in the patient's recurrence and caused a diagnostic challenge, as the splenic recurrence was initially diagnosed as a second primary high-grade spindle cell neoplasm. Both ovarian and splenic tumors displayed positive immunohistochemical staining for cytokeratin 7, cytokeratin 8/18, estrogen receptor, and paired box gene 8 (PAX-8) in the conventional serous carcinoma and the corded and hyalinized component, confirming the diagnosis of recurrent carcinoma. The behavior in this unique case of serous carcinoma associated with a distinct corded and hyalinized pattern was more aggressive than low-grade serous carcinoma, but more favorable than malignant mixed mullerian tumor.

Dendritic cell tumor in a salivary gland lymph node: a rare differential diagnosis of salivary gland neoplasms

Dendritic cell tumors are extremely rare neoplasms arising from antigen-presenting cells of the immune system. We report a case of a 69-year-old man with an unremarkable medical history who presented with a 2-months history of a gradually enlarging painless, firm, mobile, 2 × 2-cm swelling at the caudal pole of the left parotid gland without systemic symptoms. Histologically, the tumor consisted of a spindle cell proliferation in an intraparotideal lymph node. Based on the histopathologic, immunohistochemical and electron microscopic findings, a dendritic cell tumor, not otherwise specified (NOS) in an intraparotideal lymph node was diagnosed.

The patient underwent complete tumor resection, and is currently free of disease, 2 years after surgery. These extremely rare tumors must be distinguished from other more common tumors in the salivary glands. Awareness that dendritic cell tumors may occur in this localization, careful histologic evaluation and ancillary immunohistochemical and electron microscopical analyses should allow for recognition of this entity.

Molecular cytogenetic characterization of canine histiocytic sarcoma: A spontaneous model for human histiocytic cancer identifies deletion of tumor suppressor genes and highlights influence of genetic background on tumor behavior

Background

Histiocytic malignancies in both humans and dogs are rare and poorly understood. While canine histiocytic sarcoma (HS) is uncommon in the general domestic dog population, there is a strikingly high incidence in a subset of breeds, suggesting heritable predisposition. Molecular cytogenetic profiling of canine HS in these breeds would serve to reveal recurrent DNA copy number aberrations (CNAs) that are breed and/or tumor associated, as well as defining those shared with human HS. This process would identify evolutionarily conserved cytogenetic changes to highlight regions of particular importance to HS biology.

Methods

Using genome wide array comparative genomic hybridization we assessed CNAs in 104 spontaneously occurring HS from two breeds of dog exhibiting a particularly elevated incidence of this tumor, the Bernese Mountain Dog and Flat-Coated Retriever. Recurrent CNAs were evaluated further by multicolor fluorescence in situ hybridization and loss of heterozygosity analyses. Statistical analyses were performed to identify CNAs associated with tumor location and breed.

Results

Almost all recurrent CNAs identified in this study were shared between the two breeds, suggesting that they are associated more with the cancer phenotype than with breed. A subset of recurrent genomic imbalances suggested involvement of known cancer associated genes in HS pathogenesis, including deletions of the tumor suppressor genes CDKN2A/B, RB1 and PTEN. A small number of aberrations were unique to each breed, implying that they may contribute to the major differences in tumor location evident in these two breeds. The most highly recurrent canine CNAs revealed in this study are evolutionarily conserved with those reported in human histiocytic proliferations, suggesting that human and dog HS share a conserved pathogenesis.

Conclusions

The breed associated clinical features and DNA copy number aberrations exhibited by canine HS offer a valuable model for the human counterpart, providing additional evidence towards elucidation of the pathophysiological and genetic mechanisms associated with histiocytic malignancies. Extrapolation of data derived from canine histiocytic disorders to human histiocytic proliferation may help to further our understanding of the propagation and cancerization of histiocytic cells, contributing to development of new and effective therapeutic modalities for both species.

Follicular dendritic cell sarcoma: a report of six cases and a review of the Chinese literature

Goals

The main purpose of this study is to broaden the clinicopathological spectrum and increase recognition of follicular dendritic cell sarcoma (FDCS) through analysis of the clinical and pathological features of 50 cases.

Methods

The clinicopathological features of total 50 cases of FDCS were analyzed including a review of 44 cases reported in Chinese literature before October 2009 and six original cases from the pathology files conducted by the authors.

Results

The youngest patient came under observation in this study is only seven years old. Including the cases contributed by the authors, our literary review indicated that male dominated the tumor cases (M: F = 3: 2). 28 cases (56%) present with this disease in extranodal sites. Tumor cells demonstrated positive staining for the follicular dendritic cell markers CD21 (47/49), CD35 (43/45), CD23 (20/23) and CD68 (23/25). In situ hybridization for Epstein-Barr virus-encoded RNA was performed in 10 cases. Nevertheless, EBV expression was absent in all these cases. The follow-up analysis of all cases shows that 26 (81.2%) patients were alive and disease free; 6 (18.8%) patients were alive with recurrent disease or metastasis; and nobody had died of this disease at the time of last follow-up.

Conclusions

The diagnosis of the FDCS is based on the findings of morphology and immunohistochemistry. The FDCS occurred in China should be viewed and treated as a low-grade sarcoma, and the role of the EBV in the pathogenesis of this tumor is still uncertain. There is a possibility that the tumor might be racial or geographic correlated, because most cases were reported from Eastern Asia area; it's particular the case of the liver or spleen tumor.

Clinicopathological features and prognosis assessment of extranodal follicular dendritic cell sarcoma

AIM: To establish a model for prognosis assessment of extranodal follicular dendritic cell (FDC) sarcoma.

METHODS: Nine lesions were examined by routine and molecular approaches. Clinicopathological factors from the new cases and 97 reported cases were analyzed for their prognostic values.

RESULTS: The current lesions were found in five male and four female patients, located mainly in the head and neck area and averaging 7.2 cm in size. Six patients had recurrence or metastasis and three remained free of disease. The 106 patients (male/female ratio, 1.1:1) were aged from 9 to 82 years (median, 44 years). The tumor sizes ranged from 1.5 to 21 cm (mean, 7.4 cm). Abdominal/pelvic region was affected most frequently (43%). Surgical resection was performed in 100 patients, followed by radiation and/or chemotherapy in 35 of them. Follow-up data were available in 91 cases, covering a period of 3-324 mo (mean, 27 mo; median, 19 mo). Of the informative cases, 38 (42%) had recurrence or metastasis, and 12 (13%) died of the disease. These tumors were classified histologically into low- and high-grade lesions. A size ≥ 5 cm (P = 0.003), high-grade histology (P = 0.046) and a mitotic count ≥ 5/10 HPF (P = 0.013) were associated with tumor recurrence. The lesions were defined as low-, intermediate- and high-risk tumors, and their recurrence rates were 16%, 46% and 73%, and their mortality rates 0%, 4% and 45%, respectively.

CONCLUSION: Extranodal FDC tumors behave like soft tissue sarcomas. Their clinical outcomes are variable and can be evaluated according to their sizes and grades.

Extranodal follicular dendritic cell sarcoma

Extranodal follicular dendritic cell sarcoma is a rare tumor of follicular dendritic cells that can occur in a wide variety of sites. Although fairly well characterized histologically, with a distinct immunophenotype, it remains under-recognized, with as many as one third of cases initially misdiagnosed. This is often due to a failure to consider the entity. Patients with this tumor may have a worse prognosis than originally described. Prompted by a recent case at our institution, we briefly review the clinical features, etiology, histologic, and cytologic appearance of the tumor, as well as the ancillary studies useful in resolving diagnostic issues, primarily in an attempt to increase recognition of this rare neoplasm.

Cytogenetic abnormality 46,XX,add(21)(q11.2) in a patient with follicular dendritic cell sarcoma

The case of a patient with follicular dendritic cell (FDC) sarcoma with chromosomal aberration add(21)(q11.2) is described. Cytogenetic studies showed the karyotype 46,XX,add(21)(q11.2)[3]/46,XX[17], although the encoded protein involved was not clarified. The abnormal pattern was quite simple, and different from a previous report. The clinical course of the FDC sarcoma in this case has been indolent, as for most FDC sarcoma patients. Although this patient suffered from breast carcinoma 6 years after the onset of FDC sarcoma, the carcinoma showed different histological and phenotypic profiles.