Extranodal Follicular Dendritic Cell Sarcoma of the Head and Neck Region: A Clinicopathological Study of 7 Cases

Background. Follicular dendritic cell (FDC) sarcoma is a rare neoplasm arising from follicular dendritic cells (FDCs). It can be nodal or extranodal. Histological diagnosis of extranodal FDC sarcoma in the head and neck region is challenging and a significant percentage are misdiagnosed. Objectives. To report clinicopathological features of head and neck extranodal FDC sarcoma cases and discuss differential diagnoses. Methods. Seven head and neck extranodal FDC sarcomas were retrieved and clinicopathological features were noted. Results. Two tumors each involved parapharyngeal space and tonsil while remaining cases involved the parotid, soft tissue of neck and oropharynx. Age range was 12 to 79 years (mean and median age were 40 and 44 years respectively) and there was a male predilection (6 males: 1 female). All showed spindle to ovoid cells arranged in fascicles, whorls and/or storiform pattern. Mitoses ranged from 3 to 20/mm2. All tumors expressed CD21 and CD23. Two patients died of their disease at 9 and 16 months. Both had tumors larger than 5 cm with ≥10 mitoses/mm2. Three patients were alive at 12, 44 and 184 months. Conclusions. There was a distinct male predominance in our cohort. FDC sarcoma should be included in the differential diagnosis of spindle cell extranodal neoplasms in the head and neck with a whorled growth pattern and intratumoral lymphocytes. Head and neck region tumors show similar clinicopathologic characteristics as their counterparts at other locations with potential for aggressive behavior especially in tumors greater than 5 cm in size and with high mitotic rates.

Follicular Dendritic Cell Sarcomas: CT and MRI Findings in 20 Patients

OBJECTIVE. The objective of this study was to assess the imaging features of follicular dendritic cell sarcoma (FDCS) on CT and MRI. MATERIALS AND METHODS. The clinical data and pretreatment findings of 20 patients with pathologically proven FDCS on CT (n = 15), MRI (n = 7), or both (n = 2) were analyzed retrospectively. Tumor location, number, size, morphology, attenuation or signal intensity, margin, presence of metastases, and contrast enhancement were evaluated. RESULTS. FDCS originated from lymph nodes (n = 6) or a variety of extranodal sites (n = 14). The tumors were typically solitary and well-circumscribed. Extranodal lesions (mostly in the abdomen or mediastinum with mean diameter, 11.8 cm) were larger than nodal lesions (mean diameter, 6.5 cm). Nodal-type cases presented with homogeneous masses on CT and MRI. However, on CT, all extranodal tumors (n = 12) showed heterogeneous attenuation, of which 91.7% (11/12) contained areas of lower attenuation because of internal necrosis and 50.0% (6/12) showed calcifications. On MRI, primary hepatic or splenic tumors (n = 3) also appeared as large heterogeneous masses. Seven patients (35.0%) had advanced-stage disease, and intraabdominal extranodal cases were more likely to have regional lymphadenopathy (n = 4) and distant metastases (n = 5). Hypervascularity was seen in 90.0% (18/20) of patients and progressive enhancement was seen in 11 (78.6%) of 14 tumors with multiphase imaging. CONCLUSION. FDCS is a rare, mostly solitary, well-delineated malignancy. A nodal-type FDCS typically presents as a small homogeneous mass, whereas an extranodal FDCS in the mediastinum or abdomen manifests as a large heterogeneous mass with internal necrosis and calcifications accompanied by regional lymphadenopathy. Hypervascularity and progressive enhancement can be seen in the majority of tumors.

Metastatic follicular dendritic cell sarcoma treated with gemcitabine plus docetaxel with an outstanding survival: A case report and review of literature

Follicular dendritic cell sarcoma responded dramatically to chemotherapy with gemcitabine and docetaxel.

Follicular dendritic cell sarcoma of the head and neck: Case report, literature review, and pooled analysis of 97 cases

BACKGROUND

Follicular dendritic cell sarcoma (FDCS) is a rare lymphoid neoplasm presenting in the head and neck. There are no pooled analyses of head and neck FDCS cases in the English language literature.

METHODS

A MEDLINE and PubMed review of cases from 1978 to February 2014 was performed. Demographics, clinicopathologic data, and outcomes were summarized.

RESULTS

We presented 2 patients and analyzed 97 cases. The mean age was 42.7 years (SD = 16.3 years). Outcomes were available for 76 patients. Tumors ≤4 cm had better disease-free survival (63% vs 28% at 5 years; p = .0282). Locoregional recurrence was significantly less likely with surgery and radiation compared to surgery alone (15% vs 45%; p = .019) and in patients receiving a neck dissection (10% vs 43%; p = .046).

CONCLUSION

This pooled analysis provides the largest sample size of FDCS of the head and neck to date and suggests that radiation and neck dissection may be beneficial to locoregional oncologic control. © 2015 Wiley Periodicals, Inc. Head Neck 38: E2241-E2249, 2016.

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 tour of the thymus: a review of thymic lesions with radiologic and pathologic correlation

The thymus is routinely encountered on cross-sectional imaging studies of the chest. It has a variable appearance, undergoes dynamic changes during periods of stress, and demonstrates numerous different pathologic lesions. Understanding the imaging characteristics of these different lesions facilitates accurate radiographic diagnosis and can prevent unnecessary follow-up imaging and intervention. This article will review normal thymic anatomy and development, thymic hyperplasia and associated medical conditions, and the imaging and pathologic features of various benign and malignant thymic lesions.

Pediatric follicular dendritic cell sarcoma of the head and neck: a case report and review of the literature

OBJECTIVE

Follicular dendritic cell sarcoma is a rare disease with a non-specific and insidious presentation that is further complicated by difficult diagnostic and therapeutic assessment.

METHODS

The database PubMed was searched for reports of follicular dendritic cell sarcoma between 1986 (first case published) and 2012. All of the articles presenting informations regarding one or more cases of follicular dendritic cell sarcoma of the head and neck region, in patients less than 18 years of age, were included. The reference lists for pertinent reports were also scanned to ensure that all relevant literature was included.

RESULTS

We present a case of a 14 year-old girl, with a 2-month history of a right-sided level II neck mass. After a carefull radiologic evaluation the mass was resected combined with a right selective neck dissection. Histology with immunohistochemical staining was positive for follicular dendritic cell sarcoma. No recurrence was seen after 31 months follow-up. The literature search identified six more cases of pediatric follicular dendritic cell sarcoma of the head and neck. This is the first female patient with follicular dendritic cell sarcoma in the pediatric population.

CONCLUSIONS

Current treatment of head and neck follicular dendritic cell sarcoma consists of wide radical resection, with associated radiotherapy or chemotherapy only for cases with aggressive disease such as extracapsular invasion, tumor size ≥6 cm or after failure of the first-line surgical treatment.

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.

A rare case of interdigitating dendritic cell sarcoma in the nasal cavity

Interdigitating dendritic cell sarcoma (IDCS) is an extremely rare neoplasm that mainly arises from the lymphoid tissues of the immune system. Although this neoplasm typically occurs anywhere along the lymph nodes, it can also be found at extranodal sites, especially in the head and neck. We experienced a rare case of extranodal IDCS in the nasal cavity, a location that has not been previously reported. A 73-year-old woman presented with a polyp-like mass in the nasal cavity and underwent endoscopic sinus surgery. A histologic study confirmed the mass as IDCS by immunohistochemistry with S-100 antibody, and postoperative adjuvant radiotherapy was administered. Although the incidence is extremely rare, this case suggests that extranodal IDCS should be considered in the differential diagnosis of nasal cavity masses.

Extranodal follicular dendritic cell sarcoma in mesentery: A case report

Extranodal follicular dendritic cell (FDC) sarcomas are not a common phenomenon. Due to the scarcity of the identified cases reported in the literature, FDC is probably under-recognized and commonly misdiagnosed. The diagnosis of FDC sarcomas is based on node-based spindle cell lesions, and the expression of CD21, CD35 and clusterin. The most commonly involved extranodal sites include the oral cavity, tonsil, gastrointestinal tract and liver. With the aid of immunohistochemical analysis and the two most reliable FDC markers, CD21 and CD35, the diagnostic accuracy has improved. When FDC sarcoma is suspected histologically, immunohistochemical stains for FDC differentiation should be performed to avoid potential misdiagnosis. This case report concerns the evaluation of a 43-year-old male Chinese patient with a large extranodal FDC sarcoma (20×18×9 cm) in the mesentery with elevated serum CA125 (76.9 U/ml). The diagnosis and treatment of this disease are also discussed.

A follicular dendritic cell sarcoma of the mediastinum with immature T cells and association with myasthenia gravis

Follicular dendritic cell (FDC) sarcoma is a very rare neoplasm showing morphologic and phenotypic features of FDCs. It occurs primarily in lymph nodes but also in extranodal sites. So far, there have been no reports on FDC sarcoma associated with myasthenia gravis. In the following we will present a case of an FDC tumor of the mediastinum associated with paraneoplastic myasthenia gravis in a 39-year-old man. The tumor contained a major proportion of immature T cells, which may be connected to this patient's very unusual clinical presentation with autoimmune phenomena. Extranodal FDC sarcomas still seem hardly noticed, and their clinical and pathologic characteristics remain to be better defined.

Primary nasopharyngeal interdigitating dendritic cell tumor presentation and response to radiation therapy

We report the case of a primary nasopharyngeal interdigitating dendritic cell tumor (IDDCT). A 25-year old male presented with bilateral decreased hearing, double vision, and ataxia. Flexible nasopharyngoscopy reviewed a large mass obstructing and filling the entire nasopharynx. MRI and PET-CT confirmed the presence of the primary tumor and demonstrated bilateral cervical lymphadenopathy. Biopsy of the nasopharynx revealed a hematolymphoid neoplasm with dendritic cell differentiation, most consistent with an IDDCT. The lesion was unresectable. The patient was treated with definitive radiotherapy to 66 Gy to the primary tumor and 50 Gy to the bilateral cervical lymphatics using an IMRT technique. A complete response was achieved and the patient remains disease free at the primary site 23 months after completion of radiotherapy.

Thymic epithelial cells expressed unusual follicular dendritic cell markers: thymic extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue

Described herein is a case of thymic extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue. Using immunohistochemical double staining it was found that most of the thymic lymphoid follicles in this case possessed cytokeratin-positive and follicular dendritic cell (FDC) marker-positive cells. Moreover, using immunoelectron microscopy it was confirmed that some of the double-positive cells were thymic epithelial cells. The candidate of cytokeratin subtype expressed on the double-positive cells was cytokeratin 1 (CK1), which was expressed only by the epithelium of Hassall's corpuscles in thymuses from age-matched patients with myasthenia gravis. The present case indicates a possibility that some thymic epithelial cells become FDC, although it was uncertain whether they were derived from the epithelia of Hassall's corpuscles or whether they were at the same differentiation stage as Hassall's corpuscles.

Dendritic cell neoplasms: an overview

Dendritic cell neoplasms are rare tumors that are being recognized with increasing frequency. They were previously classified as lymphomas, sarcomas, or histiocytic neoplasms. The World Health Organization (WHO) classifies dendritic cell neoplasms into five groups: Langerhans' cell histiocytosis, Langerhans' cell sarcoma, Interdigitating dendritic cell sarcoma/tumor, Follicular dendritic cell sarcoma/tumor, and Dendritic cell sarcoma, not specified otherwise (Jaffe, World Health Organization classification of tumors 2001; 273-289). Recently, Pileri et al. provided a comprehensive immunohistochemical classification of histiocytic and dendritic cell tumors (Pileri et al., Histopathology 2002;59:161-167). In this article, a concise overview regarding the pathological, clinical, and therapeutic aspects of follicular dendritic, interdigitating dendritic, and Langerhans' cell tumors is presented.

Dendritic cell sarcoma: an analytic overview of the literature and presentation of original five cases

Interdigitating and follicular dendritic cell sarcoma (DCS) are very rare diseases, with approximately 184 cases being reported thus far, and their best treatment modality is still on debate. This is a review of all the cases of dendritic cell sarcoma reported from 1981 until April 2006. This review is enriched with the original contribution of five cases occurred at our Institution from 1994 to 2006. The review of the literature pointed out that radical surgery alone was curative in approximately two thirds of these cases, the relapsing rate in patients who received adjuvant treatments being higher than 30%. We pinpoint new five cases of dendritic cell sarcoma (three FDCS and two IDCS). Both the analytic revision of the literature and our data suggest that localized DCS may be effectively treated by radical surgery and do not support the use of adjuvant treatments after radical excision.

Imatinib in the Treatment of Follicular Dendritic Sarcoma: A Case Report and Review of Literature

Follicular dendritic cell sarcoma is a rare, malignant, non-lymphoid cell-derived tumor that originates from B-lymphoid follicles of nodal and extranodal sites. It has been reported in around 100 cases in the literature, mostly for the head and neck region. Surgery and radiotherapy were considered the mainstay of treatment for localized disease. As for the metastatic setting, classic lymphoma and sarcoma regimens were previously tested with dismal responses.

PATIENT AND METHODS

In this report, we examined imatinib in combination with gemcitabine and cisplatin for treating a male patient with metastatic follicular dendritic sarcoma to the liver and lung.

RESULTS

The patient achieved complete pathological remission confirmed by positron emission tomography (PET) scan after 8 cycles.

CONCLUSION

Our case is the first to report a role for imatinib and to show complete pathological remission in this rare disease. An imatinibbased combination could serve as a good therapeutic option for such cases.

Extranodal follicular dendritic cell sarcoma: clinical, pathologic, and histogenetic characteristics of an underrecognized disease entity

It has been more than 10 years since follicular dendritic cell (FDC) sarcoma was first reported to occur in extranodal sites, yet extranodal FDC sarcoma still appears underrecognized, and its clinical and pathological characteristics remain to be defined. This study analyzed the clinical and pathological findings of three such cases that the authors encountered recently and 43 previously reported cases identified in the literature. Assessment of all 46 cases showed a slight female predominance (1.2:1) with a median age of 41.5 years. One-third of the cases were misdiagnosed at initial evaluation mainly because the possibility of FDC sarcoma was not considered. When considered, this disease had distinct pathological characteristics that allowed an accurate diagnosis. Staining for FDC markers, CD21, CD35, and clusterin was particularly helpful. The pathogenesis of the disease appeared heterogeneous, and associated factors included Epstein-Barr virus infection (in hepatic cases) and inflammatory pseudotumor-like conditions. Treatment modality varied widely although surgical resection was often included. With a median follow-up of 18 months, 43% of the cases recurred and 7% died of disease. The 5-year recurrence-free survival was 27.4%. From data available at the current time, we were not able to identify prognostically significant pathologic factors.

Follicular dendritic cell sarcoma of the tonsil: a case report

Follicular dendritic cell sarcomas of the tonsil are very rare tumors. Only 10 cases have been published in the English-language medical literature. We present an additional case that occurred in a 27-year-old woman. She presented with a tumor of the right tonsil. Histological sections of tonsillar biopsies and tonsillectomy suggested that this tumor was a nerve sheath tumor or a malignant melanoma. Histological examination and immunohistochemical study were reviewed. The final diagnosis was follicular dendritic cell sarcoma. She underwent a transoral resection of the right oropharynx with ipsilateral selective neck dissection and postoperative irradiation. We emphasize the difficulties in diagnosing this type of tumor. The use of monoclonal specific markers is required to avoid misdiagnosis. We discuss therapeutic methods for this rare tumor for which optimal treatment has not yet been defined.

Extrathyroid carcinoma showing thymus-like differentiation (CASTLE) tumor--a new case report and review of literature

BACKGROUND

We report a case of extrathyroid carcinoma showing thymus-like differentiation (CASTLE) tumor.

METHODS

A 47-year-old man had a left neck mass that gradually enlarged over approximately 3 months. Sonography and CT scans showed a soft tissue mass located at the left parapharyngeal space with displacement of left carotid artery and submandibular gland.

RESULTS

After total excision, the pathologic diagnosis was CASTLE tumor. The patient then received radiotherapy with a total dosage of 6600 cGy. After 21 months of postoperative follow up, there was no evidence of recurrence.

CONCLUSION

Generally, the treatment of choice is surgical excision with or without radiotherapy. Because CASTLE tumors have been reported to be radiosensitive, however, and because local recurrence is common, surgical excision with postoperative radiotherapy is suggested.

Sarcoma Arising in Hyaline-Vascular Castleman Disease of Skin and Subcutis

We report on a case of a sarcoma arising in the hyaline-vascular variant of Castleman disease (HVCD) of the skin and subcutis. The patient was a 38-year-old man who clinically presented with a subcutaneous non-fixed cyst-like mass on his right shoulder with an unremarkable prior medical history. Histologic sections showed a biphasic tumor with numerous atretic lymphoid follicles located in the deep dermis and subcutis and a spindle-cell neoplasm mainly situated in the deep subcutis and adjacent soft tissue. The atretic lymphoid component fulfilled the criteria for HVCD, whereas the spindle-cell lesion showed all the criteria for sarcoma including nuclear atypia and frequent mitotic figures. The sarcomatous component was diffusely positive for fascin, nerve growth factor receptor, and CD34 with focal weak reactivity for CD21 and CNA.42. Stains for CD23, CD31, CD35, CD99, ALK-1, SMA, ASMA, desmin, factor XIIIa, AE1-AE3, EMA, bcl-2, S-100, Melan-A, HMB-45, Cam 5.2, and factor VIII were negative in the neoplastic spindle cells. No monoclonal population of lymphocytes was detected and we could not identify EBV or HHV-8 virus by PCR. Electron microscopy of the sarcomatous component showed spindle cells with labyrinth-like invaginations of the nucleus and numerous long, slender, interwoven cytoplasmic processes. The sarcomatous component in this case is most consistent with a poorly differentiated follicular dendritic cell sarcoma based upon the morphologic and ultrastructural findings.

Tumour Lines from a Spontaneous Rat Endometrial Stromal Sarcoma, Showing Dendritic Cell-like and Myofibroblastic Cell-like Phenotypes

A transplantable tumour (RY) and cell lines (RY-PB and clone RY-B-E3 isolated from RY-PB) were established from a naturally occurring endometrial stromal sarcoma (ESS) found in a 24-month-old female F344 rat. The primary tumour and RY tumours, which had been serially passaged in syngeneic female rats up to the 10th generation, consisted of spindle or round cells arranged in ill-defined bundles or sheets. Neoplastic cells of the primary and RY tumours, as well as cultured cells of RY-PB and RY-B-E3, showed positive reactions to vimentin, ED1/ED2 (both for rat macrophages/histiocytes), OX6 (for dendritic cells expressing rat MHC class II antigens), and lysosomal enzymes such as acid phosphatase and non-specific esterase, in varying degrees. Ultrastructurally, neoplastic cells characteristically had tubulovesicular system-like structures and variously developed lysosomes in the cytoplasm. Neoplastic cells also exhibited immunoexpression to an alpha-smooth muscle actin (alpha-SMA). The addition of transforming growth factor (TGF)-beta1 to RY-PB and RY-B-E3 cultures increased the number of alpha-SMA-positive cells, whilst the positive cell number was decreased by anti-TGF-beta antibody. The RT-PCR method revealed the expression of TGF-beta1 mRNA in the cultured cells. The present study showed that rat ESS-derived cells exhibited dendritic cell-like and myofibroblastic cell-like phenotypes. The histogenesis of ESSs in human beings and rats remains poorly understood, and these tumour lines may therefore become useful tools for further research.

Dermatofibrosarcoma protuberans with EMa+ cells. Report of a case suggesting perineurial cell differentiation

A case of dermatofibrosarcoma protuberans (DFSP) with epithelial membrane antigen (EMA)-positive cells is described. The tumor was excised from the left groin of a 28-year-old woman. It showed characteristic histologic features of DFSP with typical diffuse immunohistochemical positivity for CD34. Moreover, scattered neoplastic cells expressed EMA, suggesting perineural cell differentiation. Ultrastructural study found perineurial cell features, such as thin long bipolar cytoplasmic processes, pinocytotic vesicles, fragments of external lamina and/or external lamina-like material, attachment plaques, and desmosome-like junctions. This observation, together with previous immunohistochemical findings of EMA-positive cells in a subset of DFSPs, strongly suggests perineurial cell differentiation in these tumors. DFSP should be included in the differential diagnosis of EMA-positive spindle cell lesions of superficial soft tissue and skin.

Follicular dendritic cell tumor in the oro-pharyngeal region: report of a case and a review of the literature

A case of follicular dendritic cell tumor (FDC tumor) arised in the aro-pharyngeal region is reported in a 16-year-old Japanese boy. He had a swelling in the right retromolar trigone and soft palate. Clinical examination disclosed a 25 mm x 30 mm, elastic hard, ulcerated mass. CT scans showed a low density lesion in the right medial parapharyngeal area. The biopsy specimen revealed a low-grade malignant tumor. The patient underwent a tumorectomy which was extended to include the adjacent palatine tonsil. The tumor cells, with a clear cytoplasm and oval nucleus, were immunoreactive for S-100 (N/A), CD 21 (1F8), fascin (55K-2) and FDC (CNA42). The fascicular sheet pattern arrangement of the tumor cells was partly characteristic. The final diagnosis was an follicular dendritic cell tumor. Three courses of adjuvant chemoradiotherapy were administered postoperatively. Clinical features, pathological diagnosis and immunohistochemical markers for distinguishing FDC tumor are reviewed.

Follicular dendritic cell sarcoma of the neck; a case report and literature review

Follicular dendritic cell (FDC) sarcomas, also known as dendritic reticulum cell tumors, are uncommon neoplasms arising from antigen-presenting cells in B-lymphofollicles of nodal and extra-nodal sites. It is considered as an intermediate grade malignancy since it has significant recurrent and metastatic potential. We report a case of FDC sarcoma arising in the neck. A 56-year-old female presented with a left neck tumor. Neck dissection was performed. Microscopically, the tumor showed spindle-shaped stromal cells with large oval and polygonal nuclei. Immunohistologically, the cells were positive for CD21 and CD35, consistent with FDC sarcomas. Adjuvant chemotherapy of cyclophosphamide/doxorubicin/vincristine/prednisone (CHOP) was given. Literature review provides the current information for the diagnosis and treatment of this unusual tumor.

Accessory cell tumour: a clinicopathological study of 16 aggressive tumours containing EBV-positive Hodgkin and Reed-Sternberg-like giant cells

AIMS

Lymph nodes contain non-lymphoid accessory cells including follicular dendritic cells and interdigitating dendritic cells. Functionally, these cells belong to the category of immune accessory cells involved in antigen presentation to B or T-lymphocytes. Neoplastic proliferation of these cells is very uncommon. We present here the clinicopathological features of 16 cases of accessory cell tumour.

METHODS AND RESULTS

We performed electron microscopic and immunohistochemical examinations, and used in-situ hybridization for EBV-encoded RNA (ISH-EBV) to detect the EBV genome in 11 cases, and Southern blot analysis to assess EBV clonality in two cases. Tumour cells were composed of oval-to-spindle cells arranged in diffuse, vague storiform, fascicular and sometimes whorled patterns in a background of small lymphocytes. In all cases, binucleated or multinucleated Hodgkin and Reed-Sternberg-like giant cells were encountered. Staining for CD68 was positive in all cases. CD21, CD35, Ki-M4p, Ki-FDC1p, and S100 exhibited variable reactivity. ISH-EBV yielded positive labelling in seven of 11 cases, of which five exhibited EBV only in Hodgkin and Reed-Sternberg-like giant cells. Southern blot analysis showed clonality of EBV terminal repeats (EBV-TR) in the two cases examined. Electron microscopic examination showed that many of the tumour cells had numerous interwoven long villous cell processes connected by occasional desmosomes. Many tumours were very refractory to chemotherapy and radiation, with a few exceptions, and half of the cases classified initially as stage IV. A short survival time, of 10 months or less, was observed in seven of 16 patients.

CONCLUSIONS

Our study identified more aggressive behaviour of accessory cell tumours. Our results suggest that EBV may potentially induce activation of accessory cells to form Hodgkin and Reed-Sternberg-like giant cells, which correspond with poor prognosis.

Extranodal follicular dendritic cell sarcoma of the head and neck region: three new cases, with a review of the literature

Extranodal follicular dendritic cell (FDC) sarcoma of the head and neck region is uncommon, with 16 well-documented cases previously reported (four in the tonsil, four in the pharynx, two in the palate, five in the soft tissue, and one in the thyroid). We here report an additional three cases of extranodal FDC sarcoma in the tonsil (two cases) and pharynx (one case). In these new cases, the neoplastic cells were arranged in diffuse, fascicular, and vaguely whorled growth patterns. A background lymphocytic infiltrate was sprinkled throughout the neoplasms, with focal prominent perivascular cuffing. Scattered multinucleated giant cells were present. Immunohistochemically, tumor cells were strongly and diffusely positive for follicular dendritic cell markers CD21 and CD35. Tumor cells were diffusely positive for fascin and negative for leukocyte common antigen, S-100 protein, cytokeratin, and Epstein-Barr virus (EBV) latent membrane protein-1 (EBV-LMP). EBV was also not detected in the tumor cells by in situ hybridization for EBV-encoded RNAs. FDC sarcomas are probably an underrecognized neoplasm, especially when they occur in extranodal sites in the head and neck region. Two of the three new cases we report were initially misdiagnosed, and five cases of extranodal FDC sarcoma in the head and neck region reported in the recent literature were initially misdiagnosed. Our aim is to complement the current understanding of this neoplasm and alert pathologists to this rare entity in this region to avoid misdiagnosis. Recognition of extranodal FDC sarcoma requires a high index of suspicion, but this tumor has numerous distinctive histological features that should bring the neoplasm into the differential diagnosis. Confirmatory immunohistochemical staining with follicular dendritic cell markers such as CD21 and/or CD35 is essential for the diagnosis. Correct characterization of this neoplasm is imperative given its potential for recurrence and metastasis.

Development of follicular dendritic cell sarcoma in hyaline-vascular Castleman's disease of the nasopharynx: tracing its evolution by sequential biopsies

AIMS

Hyaline-vascular Castleman's disease (HVCD) and follicular dendritic cell (FDC) sarcoma occurring in the nasopharynx are both extremely rare. We report the first case of transformation of the former into the latter as documented by sequential biopsies. The steps involved in the transformation were described in detail and the possible role of p53 studied.

METHODS AND RESULTS

The patient presented at the age of 23 years with nasopharyngeal HVCD. Hyaline- vascular Castleman's disease with FDC overgrowth was diagnosed in a recurrence 8 years later, and a frank FDC sarcoma developed at the same site 11 years after initial presentation. The patient remained disease-free 3 years after excision and adjuvant chemotherapy. The FDC sarcoma comprised swirling fascicles of spindly cells with indistinct cell borders. The tumour cells expressed the FDC markers CD21, CD35 and CNA.42 and in-situ hybridization for Epstein-Barr virus-encoded RNAs was negative. Over-expression of p53 protein was observed in the FDC sarcoma and an increased number of weakly p53-positive spindly cells could also be demonstrated in the HVCD specimen. This finding suggested a possible role of p53 in the evolution from HVCD to FDC sarcoma. Critical analysis of the literature shows that, among the 13 reported cases of FDC sarcoma associated with Castleman's disease, possible progression from the latter to the former is documented in only two cases.

CONCLUSIONS

The sequential changes observed in the current case provide further evidence to strengthen the role of HVCD as a possible precursor of FDC sarcoma. There is a possible role of p53 in the transformation process but confirmation by future studies is needed.