The pathobiology of Kaposi’s sarcoma: advances since the onset of the AIDS epidemic

External auditory canal sebaceous carcinoma

The incidence of sebaceous carcinoma (SC) in the outer one-third of the external auditory canal is considered extremely rare, and only eight case reports have been published. We present a case of a male patient in his late 70s known case of hypertension on indapamide. His medical history included a postspinal tumour that had been treated with surgery and radiation more than 40 years ago and current complaints of right ear pain and purulent discharge. A right ear soft granular tissue mass was found. Complete debulking of the right ear mass was done in conjunction with middle ear exploration, moderately differentiated SC diagnosis was made based on the histopathological analysis. The patient was free of recurrence but then died of an unrelated pulmonary infection. SC should be suspected in elderly patients who present with long-term complaints of a mass with or without otalgia, and these patients should be examined for the presence of such tumours especially if they report a history of radiation. Additionally, more research is warranted to investigate the association of diuretics with SC.

Viral Manipulation of the Host Epigenome as a Driver of Virus-Induced Oncogenesis

Tumorigenesis due to viral infection accounts for a high fraction of the total global cancer burden (15–20%) of all human cancers. A comprehensive understanding of the mechanisms by which viral infection leads to tumor development is extremely important. One of the main mechanisms by which viruses induce host cell proliferation programs is through controlling the host’s epigenetic machinery. In this review, we dissect the epigenetic pathways through which oncogenic viruses can integrate their genome into host cell chromosomes and lead to tumor progression. In addition, we highlight the potential use of drugs based on histone modifiers in reducing the global impact of cancer development due to viral infection.

KSHV-Mediated Angiogenesis in Tumor Progression

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is a malignant human oncovirus belonging to the gamma herpesvirus family. HHV-8 is closely linked to the pathogenesis of Kaposi's sarcoma (KS) and two other B-cell lymphoproliferative diseases: primary effusion lymphoma (PEL) and a plasmablastic variant of multicentric Castleman's disease (MCD). KS is an invasive tumor of endothelial cells most commonly found in untreated HIV-AIDS or immuno-compromised individuals. KS tumors are highly vascularized and have abnormal, excessive neo-angiogenesis, inflammation, and proliferation of infected endothelial cells. KSHV directly induces angiogenesis in an autocrine and paracrine fashion through a complex interplay of various viral and cellular pro-angiogenic and inflammatory factors. KS is believed to originate due to a combination of KSHV's efficient strategies for evading host immune systems and several pro-angiogenic and pro-inflammatory stimuli. In addition, KSHV infection of endothelial cells produces a wide array of viral oncoproteins with transforming capabilities that regulate multiple host-signaling pathways involved in the activation of angiogenesis. It is likely that the cellular-signaling pathways of angiogenesis and lymph-angiogenesis modulate the rate of tumorigenesis induction by KSHV. This review summarizes the current knowledge on regulating KSHV-mediated angiogenesis by integrating the findings reported thus far on the roles of host and viral genes in oncogenesis, recent developments in cell-culture/animal-model systems, and various anti-angiogenic therapies for treating KSHV-related lymphoproliferative disorders.

Gastrointestinal tract spindle cell lesions--just like real estate, it's all about location

Interpretation of gastrointestinal tract mesenchymal lesions is simplified merely by knowing in which anatomic layer they are usually found. For example, Kaposi sarcoma is detected on mucosal biopsies, whereas inflammatory fibroid polyp is nearly always in the submucosa. Gastrointestinal stromal tumors (GISTs) are generally centered in the muscularis propria. Schwannomas are essentially always in the muscularis propria. Mesenteric lesions are usually found in the small bowel mesentery. Knowledge of the favored layer is even most important in interpreting colon biopsies, as many mesenschymal polyps are encountered in the colon. Although GISTs are among the most common mesenchymal lesions, we will concentrate our discussion on other mesenchymal lesions, some of which are in the differential diagnosis of GIST, and point out some diagnostic pitfalls, particularly in immunolabeling.

Immunohistochemical detection of the latent nuclear antigen-1 of the human herpesvirus type 8 to differentiate cutaneous epidemic Kaposi sarcoma and its histological simulators

Kaposi's sarcoma is the most common neoplasia diagnosed in AIDS patients and the expression of the human herpesvirus-8 (HHV-8) latent nuclear antigen-1 has been useful for its histological diagnosis. The aim of this study is to confirm that immunohistochemistry is a valuable tool for differentiating KS from its simulators in skin biopsies of HIV patients. Immunohistochemical and histological analyses were performed in 49 Kaposi's sarcoma skin biopsies and 60 of its histological simulators. Positivity was present in the 49 Kaposi's sarcoma skin biopsies and no staining was observed in the 60 simulators analyzed, resulting in sensibility and specificity of 100%. HHV-8 immunohistochemical detection is an effective tool for diagnosing Kaposi's sarcoma, especially in early lesions in which neoplastic features are not evident. It also contributes to its histological differential diagnosis.

Tonsillar Kaposi sarcoma in a patient with membranous glomerulonephritis on immunosuppressive therapy

Kaposi sarcoma is a malignant vascular neoplasm uncommonly seen in immunosuppressed patients. Herein we report an unusual case of tonsillar Kaposi sarcoma in a patient with membranous glomerulonephritis treated with prednisolone and cyclosporine. The patient presented after 10 months of starting the treatment with a tonsillar mass. Histological examination was typical of monomorphic spindle cell proliferation with slit-like vascular channels. The tumor cells expressed CD34, D2-40 and positive nuclear stain for HHV-8. Kaposi sarcoma is associated with immunosuppression and rarely occurs in the tonsil. Clinicians should be aware of this rare presentation of Kaposi sarcoma.

Upregulation of human β-defensin-3 and cathelicidin LL-37 in Kaposi's sarcoma

Background: Kaposi’s sarcoma (KS) is a rare neoplasm of lymphatic endothelial cells. Human herpes virus 8 (HHV-8) is considered to be a necessary, but not sufficient causal agent of KS and additional cofactors remain unknown. In this study we evaluated the expression of human β defensin (HBD)-3 and LL-37 in cutaneous lesions of KS in comparison to the healthy skin of normal subjects.

Methods: We performed a quantitative immunohistochemical study of HBD-3 and LL-37 on skin lesions from 18 patients having KS, and on healthy skin from 12 normal controls.

Results: HBD-3 and LL-37 were significantly upregulated in epidermal and dermal specimens of all KS patients in comparison to normal skin of healthy controls. The immunostaining score of dermal HBD-3 was significantly higher in nodular lesions (9.6 ± 2.4) versus plaque lesions (4.1 ± 2.2), P = 0.001. Also the immunostaining score of dermal LL-37 was significantly higher in nodular lesions versus plaque lesions (P = 0.001).

Conclusions: We have demonstrated for the first time that HBD-3 and LL-37 are significantly upregulated in lesional skin of KS in comparison to the skin of healthy controls. The obtained data suggest a possible involvement of these antimicrobial peptides in the pathogenesis of KS. However, the biological significance of HBD-3 and LL-37 in KS lesions needs further research.

Kaposi sarcoma in association with molluscum contagiosum: an uncommon diagnosis in a single biopsy and potential diagnostic pitfall

Molluscum contagiosum is a cutaneous poxviral infection that is rarely associated with other skin diseases, such as cutaneous neoplasms. Such associations are likely to be coincidental, except in immunocompromised patients. Kaposi sarcoma, an angioproliferative neoplasm derived from lymphatic endothelium, is mediated by human herpes virus-8 infection and occurs with increased frequency in immunocompromised individuals. We report an unusual case of molluscum contagiosum with underlying cutaneous Kaposi sarcoma diagnosed in a single skin biopsy of a human immunodeficiency virus-positive patient. Our case highlights the importance of adequate sampling to avoid missing secondary diagnoses in histopathologic sections and alerts pathologists and dermatologists to the possibility of coinfection in high-risk patients by 2 virally-mediated skin conditions.

Classic Kaposi's sarcoma in Han Chinese and useful tools for differential diagnosis

Kaposi's sarcoma (KS) is a common AIDS-related malignant neoplasm in the head and neck region, especially in the oral cavity, but is rarely described in the HIV-negative and non-immunosuppressed individual. Our case is of interest, because it is the first case in which manifestation of the KS occurred in the face and head areas in a patient with a Han ethnic background who had an adequate immune system. The lesions were diagnosed as angiosarcomas twice. The clinical presentation, therapeutic options, and tools for differentiating Kaposi sarcoma from other vascular and nonvascular spindle cell lesions are presented, and the relevant literature is reviewed.

Array-based transcript profiling and limiting-dilution reverse transcription-PCR analysis identify additional latent genes in Kaposi's sarcoma-associated herpesvirus

Kaposi's sarcoma-associated herpesvirus (KSHV) is a B-lymphotropic herpesvirus strongly linked to both lymphoproliferative diseases and Kaposi's sarcoma. The viral latency program of KSHV is central to persistent infection and plays important roles in the pathogenesis of KSHV-related tumors. Up to six polypeptides and 18 microRNAs are known to be expressed in latency, but it is unclear if all major latency genes have been identified. Here, we have employed array-based transcript profiling and limiting-dilution reverse transcription-PCR (RT-PCR) methodologies to explore this issue in several KSHV-infected cell lines. Our results show that RNAs encoding the K1 protein are found at low levels in most latently infected cell lines. The gene encoding v-IL-6 is also expressed as a latent transcript in some contexts. Both genes encode powerful signaling molecules with particular relevance to B cell biology: K1 mimics signaling through the B cell receptor, and v-IL-6 promotes B cell survival. These data resolve earlier controversies about K1 and v-IL-6 expression and indicate that, in addition to core latency genes, some transcripts can be expressed in KSHV latency in a context-dependent manner.

Viral epigenomes in human tumorigenesis

Viruses are associated with 15-20% of human cancers worldwide. In the last century, many studies were directed towards elucidating the molecular mechanisms and genetic alterations by which viruses cause cancer. The importance of epigenetics in the regulation of gene expression has prompted the investigation of virus and host interactions not only at the genetic level but also at the epigenetic level. In this study, we summarize the published epigenetic information relating to the genomes of viruses directly or indirectly associated with the establishment of tumorigenic processes. We also review aspects such as viral replication and latency associated with epigenetic changes and summarize what is known about epigenetic alterations in host genomes and the implications of these for the tumoral process. The advances made in characterizing epigenetic features in cancer-causing viruses have improved our understanding of their functional mechanisms. Knowledge of the epigenetic changes that occur in the genome of these viruses should provide us with markers for following cancer progression, as well as new tools for cancer therapy.

Classic Kaposi sarcoma with sarcoid-like granulomas: a case report and literature review

The occurrence of granulomatous reactions within lymph nodes that drain carcinomas is well known but uncommon. Even more rarely, granulomas may occur within the stroma of tumors. These lesions, called sarcoid-like reactions, commonly accompany carcinomas but are very rare in sarcomas. This study presents a case of classic Kaposi sarcoma that contained sarcoid-like granulomas, with a literature review. A soft tissue lesion of the foot was excised from a 74-year-old male. Histopathological examination showed that the tumor tissue consisted of spindle cells, areas of atypical vascular proliferation, and extravasated erythrocytes surrounded by non-caseating granulomas. The patient had no clinical or laboratory findings of sarcoidosis. The case was interpreted as "Kaposi sarcoma containing sarcoid-like granulomas". The association of soft tissue sarcomas with a granulomatous reaction is very rare. A granulomatous reaction is reported to be a good prognostic indicator in several carcinoma types, although its importance in sarcomas is unclear.

Synchronous follicular lymphoma, kaposi sarcoma, and castleman's disease in a HIV-negative patient with EBV and HHV-8 coinfection

The authors describe the case of a 65-year-old woman who was HIV negative and had a lymph node biopsy that showed concurrent follicular lymphoma (FL; grade 3A), Kaposi sarcoma (KS), and Castleman's disease (CD) with coinfection by human herpes virus-8 (HHV-8) and Epstein-Barr virus (EBV). The lymphoma was positive for CD20, CD10, and BCL6 and negative for BCL2. Flow cytometry showed a clonal lambda B-cell population, and polymerase chain reaction (PCR) showed a clonal immunoglobulin heavy chain gene rearrangement, confirming a neoplastic B-cell process. Focally, the FL component showed numerous EBER1-positive cells, with rare HHV-8-positive cells. The KS component showed strong HHV-8 expression with rare EBER1-positive cells. The CD component showed scattered HHV-8, viral interleukin-6, and EBER1-positive cells. The simultaneous occurrence of a FL, KS, and CD in an HIV-negative patient expands the spectrum of HHV-8-positive neoplasms and suggests the possibility of HHV-8 rendering mature B-cells hyperresponsive to antigenic stimulation, providing an expanded target for second site mutations or cytokine-driven hyperplasia, culminating in lymphoma.