Pulmonary Kaposi sarcoma in the era of highly active antiretroviral therapy

Kaposi sarcoma herpesvirus viral load in bronchoalveolar lavage as a diagnostic marker for pulmonary Kaposi sarcoma

OBJECTIVE

Kaposi sarcoma is a vascular tumor that affects the pulmonary system. However, the diagnosis of airway lesions suggestive of pulmonary Kaposi sarcoma (pKS) is reliant on bronchoscopic visualization. We evaluated the role of Kaposi sarcoma herpesvirus (KSHV) viral load in bronchoalveolar lavage (BAL) as a diagnostic biomarker in patients with bronchoscopic evidence of pKS and evaluated inflammatory cytokine profiles in BAL and blood samples.

DESIGN

In this retrospective study, we evaluated KSHV viral load and cytokine profiles within BAL and blood samples in patients who underwent bronchoscopy for suspected pKS between 2016 and 2021.

METHODS

KSHV viral load and cytokine profiles were obtained from both the circulation and BAL samples collected at the time of bronchoscopy to evaluate compartment-specific characteristics. BAL was centrifuged and stored as cell pellets and KSHV viral load was measured using primers for the KSHV K6 gene regions.

RESULTS

We evaluated 38 BAL samples from 32 patients (30 with HIV co-infection) of whom 23 had pKS. In patients with airway lesions suggestive of pKS, there was higher KSHV viral load (median 3188 vs. 0 copies/10 6 cell equivalent; P  = 0.0047). A BAL KSHV viral load cutoff of 526 copies/10 6 cells had a sensitivity of 72% and specificity of 89% in determining lesions consistent with pKS. Those with pKS also had higher IL-1β and IL-8 levels in BAL. The 3-year survival rate for pKS patients was 55%.

CONCLUSION

KSHV viral load in BAL shows potential for aiding in pKS diagnosis. Patients with pKS also have evidence of cytokine dysregulation in BAL.

Immune Reconstitution Inflammatory Syndrome Presenting as Disseminated Kaposi Sarcoma

We present a patient who was previously diagnosed with HIV and had multiple violaceous skin lesions at the time of his diagnosis. Following the initiation of antiretroviral therapy (ART), the number of lesions increased significantly and he developed shortness of breath, which prompted hospital admission for further workup. Biopsy of the skin lesions confirmed the diagnosis of Kaposi sarcoma (KS). Bronchoscopy with biopsy revealed KS lesions in his respiratory system. Imaging and biopsy confirmed KS invasion of lymph nodes. Due to widespread KS, he was diagnosed with immune reconstitution inflammatory syndrome (IRIS). Because of the lack of improvement on ART alone, he was started on chemotherapy, which decreased the size of existing skin lesions, stalled the development of new skin lesions, and led to symptom improvement. As a result of this case, we recommend that treatment teams have close follow-ups of patients started on ART and that they remain mindful of the possibility of IRIS. Disseminated KS may warrant a prompt response with chemotherapy to improve outcomes.

Pulmonary Kaposi Sarcoma as an Unusual Etiology of Acute Hypoxemic Respiratory Failure in the Era of Highly Active Antiretroviral Therapy: A Case Report

Kaposi sarcoma (KS) is caused by human herpesvirus 8 (HHV-8). Epidemic KS is described in the human immunodeficiency virus (HIV) population with acquired immune deficiency syndrome (AIDS). It primarily affects the skin, but it may uncommonly disseminate to involve extracutaneous sites such as the gastrointestinal (GI) tract, liver, and lungs.

In this case report, the authors report a 26-year-old homosexual male who was admitted with acute hypoxemic respiratory failure. He was diagnosed with an HIV infection about five months before index presentation, and he was commenced on highly active antiretroviral therapy (HAART). Physical examination was remarkable for diffuse cutaneous nodules over the lower extremities, back, and oropharynx. Chest imaging revealed diffuse bilateral infiltrates, mediastinal adenopathy, and a persistent bilateral pleural effusion. Extensive diagnostic workup was negative for underlying infectious etiology. Transbronchial biopsy demonstrated proliferated spindle cells that stained positive for HHV-8 in keeping with pulmonary KS. Skin biopsies also concurred with the diagnosis of cutaneous KS. Interestingly, the cluster of differentiation 4 (CD4) count was 647 cells/mm³, and HIV viral load (VL) was 500 copies/ml. This case demonstrated an atypical natural history of pulmonary KS in an HIV patient as pulmonary and disseminated mucocutaneous KS occurred with a relatively higher CD4 count (≥500 cells/mm³). It also reminds pulmonologists and infectious disease specialists to consider pulmonary KS as a differential diagnosis of acute hypoxemic respiratory failure in HIV patients, even in the absence of other clinical and laboratory criteria that define the AIDS stage.

Immune Reconstitution Inflammatory Syndrome Associated Kaposi Sarcoma

People living with HIV (PLWH) with advanced immunosuppression who initiate antiretroviral therapy (ART) are susceptible to the occurrence of an immune reconstitution inflammatory syndrome (IRIS). Although ART is responsible for AIDS- associated Kaposi sarcoma (KS) improvement and resolution, new onset (unmasking KS-IRIS) or sudden progression of preexisting KS (paradoxical KS-IRIS) can occur after a time delay of between a few days and 6 months after the initiation or resumption of ART, even in patients with a low degree of immunocompromise. KS-IRIS incidence varies from 2.4% to 39%, depending on study design, populations, and geographic regions. Risk factors for developing KS-IRIS include advanced KS tumor stage (T1), pre-treatment HIV viral load >5 log10 copies/mL, detectable pre-treatment plasma-KSHV, and initiation of ART alone without concurrent chemotherapy. Both paradoxical and unmasking KS-IRIS have been associated with significant morbidity and mortality, and thrombocytopenia (<100,000 platelets/mm3 at 12 weeks) has been associated with death. KS-IRIS is not to be considered as ART failure, and an ART regimen must be pursued. Systemic chemotherapy for KS in conjunction with ART is recommended and, in contrast with management of IRIS for other opportunistic infections, glucocorticoids are contra-indicated. Despite our preliminary results, the place of targeted therapies in the prevention or treatment of KS-IRIS needs further assessment.

Pulmonary Kaposi's sarcoma-an atypical clinical presentation

HIV-associated Kaposi's sarcoma is an angioproliferative neoplasia caused by infection with human herpesvirus 8. It typically presents with mucocutaneous involvement. Pulmonary Kaposi's sarcoma is rare, and an uncommon form of initial presentation of the disease. The authors present the clinical case of an HIV-positive patient with Kaposi's sarcoma who had exclusively pulmonary involvement at diagnosis. This case is highlighted for its rarity, by the diagnostic challenge it presented, and for the important role of bronchoscopy as a diagnostic tool for this pathology. Bronchoscopy allows direct visualization of the lesions and the ability to perform a bronchoalveolar lavage and directed biopsies.

Kaposi Sarcoma as Presentation of HIV - A Clinical Case

Kaposi sarcoma (KS) is the most common neoplasm of people with human immunodeficiency virus (HIV) infection. Although, in the antiretroviral therapy (ART) era, KS is a rare form of presentation of HIV/acquired immunodeficiency syndrome. The authors present a case of disseminated KS in a 23-year-old male. Just after the diagnosis the patient started ART and then chemotherapy with placlitaxel with clinical improvement. This case is highly representative of the complexity of HIV. The authors aim to bring awareness of an unusual form of presentation of HIV, and recall the severity and the necessity of an early diagnosis and treatment.

The potential impacts of early secreted antigenic target of 6 kDa of Mycobacterium tuberculosis on KSHV-infected cells

Kaposi's sarcoma-associated herpesvirus (KSHV) causes several human cancers, including Kaposi's sarcoma (KS) and primary effusion lymphoma, which are mostly seen in immunocompromised patients, such as human immunodefeciency virus (HIV)+ individuals. Tuberculosis (TB), caused by the bacterial pathogen Mycobacterium tuberculosis (Mtb), remains one of the deadliest infectious diseases in the world. The risk of developing TB is dramatically higher in people living with HIV than among those without HIV infection. Case reports link cutaneous or pulmonary KS in HIV+ patients with mycobacterial co-infections, however, impacts of Mtb infection or its products on KSHV-infected cells are not known. We report here that ESAT-6, a secreted Mtb virulence factor, induces viral reactivation from KSHV-infected cells. KSHV-infected pulmonary endothelial cells were resistant to ESAT-6 induced inhibition of cell growth. Our data demonstrate that Mtb virulence factors influence the biology of KSHV-infected cells, highlighting the need to study the interactions between these two pathogens commonly found in people living with HIV.

Diagnostic and management considerations in the modern patient with AIDS: a case of concurrent disseminated Kaposi sarcoma and colesional Cryptococcus neoformans

In the era of highly active antiretroviral therapy (HAART), disseminated Kaposi sarcoma (KS) has become much rarer in the USA. We report a case of a 34-year-old man with KS of the skin, oropharynx, lung and rectum. Within the same lung nodule, we discovered significant burden of colesional Cryptococcus neoformans, in the context of a positive asymptomatic cryptococcal antigenemia, which was a previously unreported occurrence. The gold standard of treatment for KS continues to be HAART. The role of chemotherapy is still controversial. In addition, a cryptococcal antigen screen-and-treat approach with fluconazole is still not routinely recommended in the USA to prevent serious meningeal disease despite recent studies showing efficacy and applicability. We discuss both issues here and the outcome of our patient. We also present the patient's own unique perspective in dealing with the ramifications of these diagnoses.

A rare case of pulmonary Kaposi sarcoma presented with respiratory failure

Kaposi sarcoma (KS) is the most commonly diagnosed malignancy in HIV-infected patients. With new treatments, incidence and severity of KS have significantly decreased.

A 57-year-old African American male with medical history of AIDS presented with progressively worsening cough, shortness of breath, fever, night sweats, and 60 lb weight loss. On physical examination, he had diffused dark purple skin lesions and decreased air entry in the right lower lung fields. Chest x-ray and subsequent chest computed tomography (CT) showed moderate right lung pleural effusion with scattered bilateral diffuse infiltrates. The patient’s absolute CD4 count was 27 cells/microliter. Thoracentesis was negative for infection or malignancy. He was started on chemotherapy paclitaxel along with HAART for extensive pulmonary KS. Since starting the treatment, his condition has significantly improved with near complete resolution of the pleural effusion, oral, and skin lesions.

In conclusion, the diagnosis of AIDS-related pulmonary KS is often clinical, typically based on the presence of mucocutaneous disease and compatible features on CT chest. The differential diagnosis of pulmonary KS is broad. A detailed evaluation should exclude an infectious etiology or other tumors. Chemotherapy along with HAART can be used for treatment of severe pulmonary KS.

Sexual dimorphism in the incidence of human cancers

Background

Sex differences in the incidences of cancers become a critical issue in both cancer research and the development of precision medicine. However, details in these differences have not been well reported. We provide a comprehensive analysis of sexual dimorphism in human cancers.

Methods

We analyzed four sets of cancer incidence data from the SEER (USA, 1975–2015), from the Cancer Registry at Mayo Clinic (1970–2015), from Sweden (1970–2015), and from the World Cancer Report in 2012.

Results

We found that all human cancers had statistically significant sexual dimorphism with male dominance in the United States and mostly significant in the Mayo Clinic, Sweden, and the world data, except for thyroid cancer, which is female-dominant.

Conclusions

Sexual dimorphism is a clear but mostly neglected phenotype for most human cancers regarding the clinical practice of cancer. We expect that our study will facilitate the mechanistic studies of sexual dimorphism in human cancers. We believe that fully addressing the mechanisms of sexual dimorphism in human cancers will greatly benefit current development of individualized precision medicine beginning from the sex-specific diagnosis, prognosis, and treatment.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5902-z) contains supplementary material, which is available to authorized users.

Regulation of sex hormone receptors in sexual dimorphism of human cancers

Gender differences in the incidences of cancers have been found in almost all human cancers. However, the mechanisms that underlie gender disparities in most human cancer types have been under-investigated. Here, we provide a comprehensive overview of potential mechanisms underlying sexual dimorphism of each cancer regarding sex hormone signaling. Fully addressing the mechanisms of sexual dimorphism in human cancers will greatly benefit current development of precision medicine. Our discussions of potential mechanisms underlying sexual dimorphism in each cancer will be instructive for future cancer research on gender disparities.

Disseminated AIDS-related Kaposi's sarcoma

We present a case of disseminated Kaposi’s sarcoma with both cutaneous and extracutaneous involvement in an HIV-infected patient with a relatively high CD4 count of 369 cell/mm³. He developed chronic diarrhea, constitutional symptoms, worsening bilateral pleural effusion with respiratory distress, and progression of skin lesions distributed over his chest and extremities. The temporal relationship between rapid clinical progression and initiation of HAART suggested the possibility of Kaposi’s sarcoma-associated immune reconstitution inflammatory syndrome, which eventually resulted in the death of this patient.

Clinical characteristics, predictors of immune reconstitution inflammatory syndrome and long-term prognosis in patients with Kaposi sarcoma

Objective

To investigate the predictive factors for the development of Kaposi sarcoma-related immune reconstitution inflammatory syndrome (KS-IRIS) and long-term prognosis in patients starting combined antiretroviral therapy (cART).

Methods

We studied a retrospective-cohort of consecutive antiretroviral-naïve patients with KS initiating cART from January 2005 to December 2011 and followed through June 2013. KS-IRIS was defined as ≥2 of the following: abrupt increase in number of KS lesions, appearance or exacerbation of lung-opacities or lymphedema, concomitantly with an increase in CD4+ cell-count ≥50 cells/mm³ and a decrease of >1 log in viral-load once started cART. We compared individuals who met KS-IRIS criteria with those that did not and described the long-term follow-up.

Results

We included 89 patients, 88 males; 35 (39%) developed KS-IRIS at a median of 10 weeks (IQR 4–16). KS-IRIS patients had more pulmonary-involvement (60% vs. 16.6% of patients; p < 0.0001), eight died attributed to pulmonary-KS. Thrombocytopenia <100,000/mm³ at follow-up occurred in 36% of KS-IRIS vs. 4% in non-KS-IRIS patients (p = 0.0002), 45% KS-IRIS patients with thrombocytopenia died, non without KS-IRIS. Chemotherapy (bleomicyn–vincristine) was more frequently prescribed in KS-IRIS patients (88.6% vs. 29.6%) with no differences in outcome; 80% of all patients achieve KS complete remission, 52% of them never received chemotherapy. No difference between groups in the long-term follow-up (mean 52.4 ± 27.4 months) was found, only one patient developed a secondary malignancy (1.12%).

Conclusions

Lung-involvement was predictive of IRIS development. Thrombocytopenia in KS-IRIS patients at week 12 follow-up after cART initiation was associated with high mortality. Over a third of patients with KS achieve remission without chemotherapy. Individuals that survive the initial period of KS-IRIS adhere to cART had a good long-term prognosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12981-017-0156-9) contains supplementary material, which is available to authorized users.

Simultaneous presentation of two noninflammatory lung diseases in an HIV-infected patient

The simultaneous presentation of two noninflammatory pulmonary diseases, pulmonary alveolar proteinosis and Kaposi's sarcoma (Ks), in an HIV-infected patient, is described. A 29-year-old black race patient was admitted to the hospital because of general malaise, weight loss, dyspnea, chest pain, and cough with hemoptoic expectoration. Chest X-rays revealed a patchy bilateral alveolar pattern with a tendency toward the formation of condensations. The serological test revealed HIV positivity (CD4 counts of 393 cells/mm³). Because there was no response to the treatment course, a thoracic CT was performed, showing interlobular thickening with intralobular septal lines and ground glass opacities ("crazy-paving" pattern). An open lung biopsy was performed. Histopathological diagnosis of pulmonary alveolar proteinosis and pulmonary Ks was made.

Pulmonary Kaposi Sarcoma: An Uncommon Cause of Respiratory Failure in the Era of Highly Active Antiretroviral Therapy-Case Report and Review of the Literature

Kaposi Sarcoma (KS) is the most common malignancy associated with Acquired Immune Deficiency Syndrome (AIDS) and is caused by Human Herpesvirus 8 (HHV 8) or Kaposi Sarcoma Herpesvirus (KSHV). In about 90% of cases Kaposi Sarcoma is associated with cutaneous lesions; however visceral disease can occur in the absence of cutaneous involvement. In the era of Highly Active Antiretroviral Therapy (HAART), the incidence of KS has declined. Clinical features of pulmonary KS might be difficult to distinguish from pneumonia in the immunocompromised patients and could lead to diagnostic challenges. First-line treatment of KS is with HAART and the incidence has declined with its use. Systemic chemotherapy may play a role depending on the extent of the disease. We report the case of a young man who presented with pulmonary symptoms and was later found to have pulmonary KS. Interestingly this diagnosis was made in the absence of the classic skin lesions. His disease was complicated by progressive respiratory failure and he eventually died.

Lung Malignancies in HIV Infection

Pulmonary malignancies are a major source of morbidity and mortality in HIV-infected persons. Non-AIDS-defining lung cancers (mostly non-small cell lung cancers) are now a leading cause of cancer death among HIV-infected persons. HIV-associated factors appear to affect the risk of lung cancer and may adversely impact cancer treatment and outcomes. HIV infection also may modify the potential harms and benefits of lung cancer screening with computed tomography. AIDS-defining lung malignancies include pulmonary Kaposi sarcoma and pulmonary lymphoma, both of which are less prevalent with widespread adoption of antiretroviral therapy.

Noninfectious pulmonary complications of human immunodeficiency virus infection

Human immunodeficiency virus type 1 (HIV-1) is the retrovirus responsible for the development of AIDS. Its profound impact on the immune system leaves the host vulnerable to a wide range of opportunistic infections not seen in individuals with a competent immune system. Pulmonary infections dominated the presentations in the early years of the epidemic, and infectious and noninfectious lung diseases remain the leading causes of morbidity and mortality in persons living with HIV despite the development of effective antiretroviral therapy. In addition to the long known immunosuppression and infection risks, it is becoming increasingly recognized that HIV promotes the risk of noninfectious pulmonary diseases through a number of different mechanisms, including direct tissue toxicity by HIV-related viral proteins and the secondary effects of coinfections. Diseases of the airways, lung parenchyma and the pulmonary vasculature, as well as pulmonary malignancies, are either more frequent in persons living with HIV or have atypical presentations. As the pulmonary infectious complications of HIV are generally well known and have been reviewed extensively, this review will focus on the breadth of noninfectious pulmonary diseases that occur in HIV-infected individuals as these may be more difficult to recognize by general medical physicians and subspecialists caring for this large and uniquely vulnerable population.

Pulmonary Kaposi's sarcoma as the initial presentation of human immunodeficiency virus infection

Kaposi's sarcoma (KS) usually presents in HIV-infected patients with cutaneous lesions that may advance to extensive visceral disease. There have been only a few documented cases in which the initial presentation of Kaposi's sarcoma involved the bronchopulmonary system. We describe a newly diagnosed patient who presented with pulmonary KS as his initial presentation of the disease. Our report is intended to increase clinicians’ awareness that pulmonary Kaposi's sarcoma should be considered in HIV-infected patients who present with respiratory symptoms, even if they do not manifest the typical mucocutaneous manifestations of KS or have low CD4 counts. Early diagnosis and therapy are essential in improving outcomes as this condition carries a high mortality.

Treatment of severe or progressive Kaposi's sarcoma in HIV-infected adults

BACKGROUND

Kaposi's sarcoma remains the most common cancer in Sub-Saharan Africa and the second most common cancer in HIV-infected patients worldwide. Since the introduction of highly active antiretroviral therapy (HAART), there has been a decline in its incidence.However, Kaposi's sarcoma continues to be diagnosed in HIV-infected patients.

OBJECTIVES

To assess the added advantage of chemotherapy plus HAART compared to HAART alone; and the advantages of different chemotherapy regimens in HAART and HAART naive HIV infected adults with severe or progressive Kaposi's sarcoma.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and , GATEWAY, the WHO Clinical Trials Registry Platform and the US National Institutes of Health's ClinicalTrials.gov for ongoing trials and the Aegis archive of HIV/AIDS for conference abstracts. An updated search was conducted in July 2014.

SELECTION CRITERIA

Randomised trials and observational studies evaluating the effects of any chemotherapeutic regimen in combination with HAART compared to HAART alone, chemotherapy versus HAART, and comparisons between different chemotherapy regimens.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the studies independently and extracted outcome data.We used the risk ratio (RR) with a 95% confidence interval (CI) as the measure of effect.We did not conduct meta-analysis as none of the included trials assessed identical chemotherapy regimens.

MAIN RESULTS

We included six randomised trials and three observational studies involving 792 HIV-infected adults with severe Kaposi's sarcoma.Seven studies included patients with a mix of mild to moderate (T0) and severe (T1) Kaposi's sarcoma. However, this review was restricted to the subset of participants with severe Kaposi's sarcoma disease.Studies comparing HAART plus chemotherapy to HAART alone showed the following: one trial comparing HAART plus doxorubicin,bleomycin and vincristine (ABV) to HAART alone showed a significant reduction in disease progression in the HAART plus ABV group (RR 0.10; 95% CI 0.01 to 0.75, 100 participants); there was no statistically significant reduction in mortality and no difference in adverse events. A cohort study comparing liposomal anthracyclines plus HAART to HAART alone showed a non-statistically significant reduction in Kaposi's sarcoma immune reconstitution inflammatory syndrome in patients that received HAART plus liposomal anthracyclines (RR 0.49; 95% CI 0.16 to 1.55, 129 participants).Studies comparing HAART plus chemotherapy to HAART plus a different chemotherapy regimen showed the following: one trial involving 49 participants and comparing paclitaxel versus pegylated liposomal doxorubicin in patients on HAART showed no difference in disease progression. Another trial involving 46 patients and comparing pegylated liposomal doxorubicin versus liposomal daunorubicin showed no participants with progressive Kaposi's sarcoma disease in either group.Studies comparing different chemotherapy regimens in patients from the pre-HAART era showed the following: in the single RCT comparing liposomal daunorubicin to ABV, there was no significant difference with the use of liposomal daunorubicin compared to ABV in disease progression (RR 0.78; 95% CI 0.34 to 1.82, 227 participants) and overall response rate. Another trial involving 178 participants and comparing oral etoposide versus ABV demonstrated no difference in mortality in either group. A non-randomised trial comparing bleomycin alone to ABV demonstrated a higher median survival time in the ABV group; there was also a non-statistically significant reduction in adverse events and disease progression in the ABV group (RR 11; 95% CI 0.67 to 179.29, 24 participants).An additional non-randomised study showed a non-statistically significant overall mortality benefit from liposomal doxorubicin as compared to conservative management consisting of either bleomycin plus vinblastine, vincristine or single-agent antiretroviral therapy alone (RR 0.93; 95% CI 0.75 to 1.15, 29 participants). The overall quality of evidence can be described as moderate quality. The quality of evidence was downgraded due to the small size of many of the included studies and small number of events.

AUTHORS' CONCLUSIONS

The findings from this review suggest that HAART plus chemotherapy may be beneficial in reducing disease progression compared to HAART alone in patients with severe or progressive Kaposi's sarcoma. For patients on HAART, when choosing from different chemotherapy regimens, there was no observed difference between liposomal doxorubicin, liposomal daunorubicin and paclitaxel.

An interesting case of 'diabetic foot ulcer' in an HIV-positive patient

Kaposi sarcoma is a highly vascularised tumour affecting the skin, lymph nodes and viscera. Kaposi sarcoma is most common in HIV-infected homosexual or bisexual men. We present here a 70-year-old white British male patient, who was under the care of the podiatric team for longstanding 'diabetic foot ulcers'. He was later referred to the Dermatology team who took a biopsy; this revealed features of Kaposi sarcoma which prompted an HIV test which was positive. This patient had previously presented to several healthcare professionals with symptoms suggestive of HIV infection. He was started on antiretroviral therapy and the HIV and human herpesvirus-8 viral loads became undetectable in the blood within weeks and he showed significant clinical improvement. This case report is a reminder to clinicians to have a high index of suspicion in patients presenting with symptoms and signs suggestive of HIV infection.

Human immunodeficiency virus-associated lung malignancies

This review of lung malignancies in human immunodeficiency virus (HIV) briefly highlights key epidemiologic and clinical features in the pulmonary involvement of AIDS-defining malignancies of Kaposi sarcoma and non-Hodgkin lymphoma. Then, focusing on non-AIDS defining lung cancer, the epidemiology and mechanisms, clinical presentation, pathology, treatment and outcomes, and prevention of HIV-associated lung cancer are discussed. Finally, the important knowledge gaps and future directions for research related to HIV-associated lung malignancies are highlighted.

Chest neoplasms with infectious etiologies

A wide spectrum of thoracic tumors have known or suspected viral etiologies. Oncogenic viruses can be classified by the type of genomic material they contain. Neoplastic conditions found to have viral etiologies include post-transplant lymphoproliferative disease, lymphoid granulomatosis, Kaposi’s sarcoma, Castleman’s disease, recurrent respiratory papillomatosis, lung cancer, malignant mesothelioma, leukemia and lymphomas. Viruses involved in these conditions include Epstein-Barr virus, human herpes virus 8, human papillomavirus, Simian virus 40, human immunodeficiency virus, and Human T-lymphotropic virus. Imaging findings, epidemiology and mechanism of transmission for these diseases are reviewed in detail to gain a more thorough appreciation of disease pathophysiology for the chest radiologist.

Pulmonary involvement in Kaposi sarcoma: correlation between imaging and pathology

Kaposi sarcoma is a low-grade mesenchymal tumor involving blood and lymphatic vessels. There are four variants of this disease, each presenting a different clinical manifestation: classic or sporadic, African or endemic, organ transplant-related or iatrogenic, and AIDS-related or epidemic. Kaposi sarcoma is the most common tumor among patients with HIV infection, occurring predominantly in homosexual or bisexual men. The pulmonary involvement in Kaposi sarcoma occurs commonly in critically immunosupressed patients who commonly have had preceding mucocutaneous or digestive involvement.

The etiology of Kaposi sarcoma is not precisely established; genetic, hormonal, and immune factors, as well as infectious agents, have all been implicated. There is evidence from epidemiologic, serologic, and molecular studies that Kaposi sarcoma is associated with human herpes virus type 8 infection. The disease starts as a reactive polyclonal angioproliferative response towards this virus, in which polyclonal cells change to form oligoclonal cell populations that expand and undergo malignant transformation.

The diagnosis of pulmonary involvement in Kaposi sarcoma usually can be made by a combination of clinical, radiographic, and laboratory findings, together with the results of bronchoscopy and transbronchial biopsy. Chest high-resolution computed tomography scans commonly reveal peribronchovascular and interlobular septal thickening, bilateral and symmetric ill-defined nodules in a peribronchovascular distribution, fissural nodularity, mediastinal adenopathies, and pleural effusions. Correlation between the high-resolution computed tomography findings and the pathology revealed by histopathological analysis demonstrate that the areas of central peribronchovascular infiltration represent tumor growth involving the bronchovascular bundles, with nodules corresponding to proliferations of neoplastic cells into the pulmonary parenchyma. The interlobular septal thickening may represent edema or tumor infiltration, and areas of ground-glass attenuation correspond to edema and the filling of air spaces with blood. These findings are a result of the propensity of Kaposi sarcoma to grow in the peribronchial and perivascular axial interstitial spaces, often as continuous sheets of tumor tissue.

In conclusion, radiological findings can play a major role in the diagnosis of pulmonary Kaposi sarcoma since characteristic patterns may be observed. The presence of these patterns in patients with AIDS is highly suggestive of Kaposi sarcoma.

Kaposi sarcoma as a model of oncogenesis and cancer treatment

Kaposi sarcoma is the most common cancer among HIV-infected individuals and one of the most common cancers in sub-Saharan Africa. Kaposi sarcoma lesions are highly vascularized, and comprised of spindle-shaped tumor cells. Kaposi sarcoma herpesvirus is etiologically linked to Kaposi sarcoma development and encodes genes that contribute to cellular transformation, evasion of apoptosis, aberrant angiogenesis and an inflammatory tumor microenvironment. The study of Kaposi sarcoma herpesvirus-driven malignancies has provided a model of oncogenesis and identified some of the key steps and, therefore, therapeutic targets of Kaposi sarcoma development. However, current Kaposi sarcoma treatments are not specific and rely on reconstitution of the immune system and systemic administration of cytotoxic agents. Recent studies have demonstrated that mechanism-based therapeutics, such as vascular endothelial growth factor A or mammalian target of rapamycin inhibitors, are promising therapeutic approaches bridging basic research with clinical practice.