Unicentric Castleman Disease: Illustration of Its Morphologic Spectrum and Review of the Differential Diagnosis

CONTEXT.—

Unicentric Castleman disease (UCD) is a dynamic entity with a wide spectrum of morphologic findings. UCD can be further subdivided into hyaline-vascular and mixed/plasmacytic variants. Hyaline-vascular UCD has both follicular and interfollicular (stromal) changes, and occasionally these lesions show a skewed representation of either the follicular or stromal compartments. Plasmacytosis is usually minimal in the hyaline-vascular variant. The mixed/plasmacytic variant of UCD is composed of sheets of plasma cells often associated with a variable number of follicles with regressive changes.

OBJECTIVE.—

To illustrate the differential diagnosis of UCD, as it is quite broad and includes lymphomas, plasma cell neoplasms, stromal neoplasms such as follicular dendritic cell sarcoma and vascular neoplasms, immunoglobulin G4-related disease, infections, and other rare lesions. An additional objective is to enhance awareness of the morphologic features of UCD in excisional and in small core-needle biopsy specimens, the latter of which may inadvertently target follicle- or stroma-rich areas, causing diagnostic challenges.

DATA SOURCES.—

In this review, we provide readers a concise illustration of the morphologic spectrum of UCD that we have encountered in our practice and a brief discussion of entities in the differential diagnosis.

CONCLUSIONS.—

UCD exhibits a broad spectrum of morphologic changes, and awareness of these morphologic variations is key to avoid misdiagnosis.

Concomitant malignancies in the neck: follicular dendritic cell sarcoma; a rare tumour presenting as a right-sided neck nodal mass and papillary carcinoma thyroid

Follicular dendritic cell sarcoma is a rare low-grade sarcoma of mesenchymal origin. It involves the lymph nodes more commonly and rarely extranodal sites. The most common lymph node is cervical and usually presents as a painless asymptomatic mass. More often, it is a misdiagnosis, and there is a delay in treatment. It is rarely associated with Castleman disease, myasthenia gravis. Diagnosis of this condition is by histopathology and immunochemistry. Surgery is the primary modality of treatment, and adjuvant therapy has been tried with no definite trials due to the rarity of the disease. Here, we report a case of concomitant follicular dendritic sarcoma of the right cervical lymph node and papillary carcinoma of the thyroid managed in our institute. There was a line of investigations approaching towards a diagnosis, and she underwent total thyroidectomy and right modified radical neck dissection.

Germinal Center Cells Turning to the Dark Side: Neoplasms of B Cells, Follicular Helper T Cells, and Follicular Dendritic Cells

Gaining knowledge of the neoplastic side of the three main cells—B cells, Follicular Helper T (Tfh) cells, and follicular dendritic cells (FDCs) —involved in the germinal center (GC) reaction can shed light toward further understanding the microuniverse that is the GC, opening the possibility of better treatments. This paper gives a review of the more complex underlying mechanisms involved in the malignant transformations that take place in the GC. Whilst our understanding of the biology of the GC-related B cell lymphomas has increased—this is not reviewed in detail here—the dark side involving neoplasms of Tfh cells and FDCs are poorly studied, in great part, due to their low incidence. The aggressive behavior of Tfh lymphomas and the metastatic potential of FDCs sarcomas make them clinically relevant, merit further attention and are the main focus of this review. Tfh cells and FDCs malignancies can often be misdiagnosed. The better understanding of these entities linked to their molecular and genetic characterization will lead to prediction of high-risk patients, better diagnosis, prognosis, and treatments based on molecular profiles.

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.

Modern diagnostic methods of paraneoplastic pemphigus

Paraneoplastic pemphigus (PNP) is one of the least investigated and rare forms of bullous dermatoses, which comes from underlying neoplasm. The article presents a literature review of dermatologist`s longstanding international experience about etiology, pathogenesis, diagnostics and treatment of this disease. According to the research results of native and foreign authors systematization of modern diagnostic methods of PNP and detectable antigens was performed.

Conflict of interest: the authors state that there is no potential conflict of interest requiring disclosure in this article.

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.

Follicular Dendritic Cell Sarcoma

Follicular dendritic cell sarcoma is an uncommon neoplastic proliferation of spindled to ovoid cells with morphologic and immunophenotypic features similar to normal follicular dendritic cells. While most follicular dendritic cell sarcomas arise from lymph nodes, at least one-third occur in extranodal sites. A broad differential diagnosis can be developed--as this tumor has morphologic features similar to other tumors, hence creating a diagnostic pitfall--but its immunophenotypic profile is quite specific and is diagnostically crucial. Herein, we review the pathogenesis; histologic morphology; and immunohistochemical, electron microscopy, and clinical features, including treatment and prognosis, of follicular dendritic cell sarcomas. We will briefly describe the role of molecular studies including utility of BRAF mutations in diagnosing this tumor.

Paraneoplastic pemphigus and myasthenia gravis, associated with inflammatory pseudotumor-like follicular dendritic cell sarcoma: response to rituximab

Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease associated with neoplasms. The disease is most commonly of lymphoproliferative origin and presents high mortality. We describe a patient with PNP and myasthenia gravis associated with inflammatory pseudotumor‐like follicular dendritic cell sarcoma, as well as the response to rituximab.

Follicular dendritic cell sarcoma of the stomach: case report and review of the literature

Follicular dendritic cell sarcoma (fdcs) is a rare entity, often presenting a diagnostic challenge for both the pathologist and the clinician. It accounts for only 0.4% of soft-tissue sarcomas, and its underlying causes are largely unknown. Most of these tumours occur in lymph nodes, and extranodal involvement is uncommon. In the gastrointestinal tract, fdcs is extremely rare. Here, we report a case of primary fdcs originating in the stomach. Upon review of the literature, we identified only 2 additional cases of fdcs presenting as a primary stomach tumour. Given the rarity of this tumour in gastrointestinal sites and the lack of consensus on treatment, evaluation of this entity must continue.

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.

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.

Myasthenia gravis developing in an HIV-negative patient with Kaposi's sarcoma

Myasthenia gravis is a disorder of neuromuscular transmission caused by autoimmune mechanisms. We reported a possible association between seropositive myasthenia gravis and Kaposi's sarcoma in a HIV-negative subject and the observed interactions between the treatment regimen for these two conditions. A 62-year-old man came to our attention for ocular myasthenia gravis. He suffered from a classic form of Kaposi's sarcoma since about 1 year. When myasthenic symptoms worsened, the patient was started on prednisone and azathioprine. The patient had a significant worsening of Kaposi's sarcoma, so prednisone and azathioprine were reduced and he was treated with vinblastine, with improvement both in dermatologic than in neurological symptomatology. We propose some considerations: the potential correlation between Kaposi's sarcoma and myasthenia gravis through immunological mechanism; myasthenia gravis as a paraneoplastic manifestation of Kaposi's sarcoma, and the role of an antitumoral agent as a treatment for both the conditions.

Summary of the 15th annual Atlantic Canada Oncology Group Symposium

The Atlantic Canada Oncology Group (ACOG) Symposium is an annual meeting. For the first 8 years it was held in Cornerbrook (NL, Canada) and for the last 7 years it has been held in Prince Edward Island (Canada). The target audience are medical and radiation oncologists from across the Atlantic Canadian provinces, but surgical oncologists, gynecologists, nurses, pharmacists, researchers, residents and other healthcare providers who work in oncology also benefit from the content presented at this meeting. The primary learning objectives are to promote cooperation among cancer programs in Atlantic Canada and to improve the quality of patients' cancer care. Each year the meeting focuses on specific tumor sites, as well as other time sensitive topics. This year's meeting focused on the management of genitourinary and gastrointestinal malignancies.