Primary penile Kaposi’s sarcoma in HIV-seronegative patient: a case report and literature review

Background Kaposi’s Sarcoma (KS) is a reticuloendothelial system tumor, that may involve the skin, mucosa and viscera (1). It can be considered a malignant vasoformative neoplasia with endothelial proliferation and spindle cell formation on histologic examination. In recent years, there have been several changes in our understanding of KS, including its evolving epidemiology, pathogenesis, new clinical presentations and associations, descriptions of new histologic variants, and the emergence of novel biomarkers with promising targeted therapeutic agents (2). Despite these advances, KS remains the most prevalent malignancy among patients with acquired immune deficiency syndrome (AIDS), being related with drugs or transplant-associated immunosuppression. To our knowledge, this disease has a tight link to Human Herpesvirus 8 (HHV-8) infection, also known as KSHV (Kaposi Sarcoma-associated Herpes Virus). KS can occur in five different epidemiologic-clinical settings: AIDS-related (also known as epidemic), iatrogenic (iatrogenic immunodeficiency, such as that seen in organ transplant recipients), endemic (commonly in sub-Saharan Africa in individuals seronegative for human immunodeficiency virus, HIV), Classic (also known as sporadic KS) and MSM (man who have sex with man) without HIV infection, who are young or middle aged, not immunocompromised (3, 4). The epidemiology suggests that this cancer had an origin independent of HIV, as well as a directed search of DNA led to the discovery of KSHV involvement in the pathogenesis of KS (5). Actually, it is known that a combination of KSHV infection and impaired host immunity might be responsible for KS. However, although AIDS related KS and iatrogenic KS are associated with well defined immunodeficiency, the impaired immune function in classic KS (related to ‘immunosenescence’, as an ageing immune system) and endemic KS (related to chronic infection and malnutrition) is not exactly characterized. In addition, KSHV can cause: I) two lymphoproliferative disorders, represented by the primary effusion lymphoma (PEL) (6) and the multicentric Castleman disease (MCD) (7), II) an inflammatory syndrome called KSHV inflammatory cytokine syndrome. Whit regard to the clinical presentation, each recognized variant has different manifestations and different visceral involvement. It has been estimated that KS confined to the penis is uncommon and is more often observed in patients with AIDS (8), representing the first manifestation of KS in approximately 2 to 3% of HIV-positive patients. Otherwise, up to 20% of these patients may develop genital lesions in the course of the systemic disease (9, 10). Even more rare primary KS of the penis may be in case of HIV seronegative patients. Primary penile Kaposi’s sarcoma in HIV-seronegative patient: a case report and literature review _______________________________________________


Background
Kaposi's Sarcoma (KS) is a reticuloendothelial system tumor, that may involve the skin, mucosa and viscera (1). It can be considered a malignant vasoformative neoplasia with endothelial proliferation and spindle cell formation on histologic examination. In recent years, there have been several changes in our understanding of KS, including its evolving epidemiology, pathogenesis, new clinical presentations and associations, descriptions of new histologic variants, and the emergence of novel biomarkers with promising targeted therapeutic agents (2). Despite these advances, KS remains the most prevalent malignancy among patients with acquired immune deficiency syndrome (AIDS), being related with drugs or transplant-associated immunosuppression. To our knowledge, this disease has a tight link to Human Herpesvirus 8 (HHV-8) infection, also known as KSHV (Kaposi Sarcoma-associated Herpes Virus). KS can occur in five different epidemiologic-clinical settings: AIDS-related (also known as epidemic), iatrogenic (iatrogenic immunodeficiency, such as that seen in organ transplant recipients), endemic (commonly in sub-Saharan Africa in individuals seronegative for human immunodeficiency virus, HIV), Classic (also known as sporadic KS) and MSM (man who have sex with man) without HIV infection, who are young or middle aged, not immunocompromised (3,4). The epidemiology suggests that this cancer had an origin independent of HIV, as well as a directed search of DNA led to the discovery of KSHV involvement in the pathogenesis of KS (5). Actually, it is known that a combination of KSHV infection and impaired host immunity might be responsible for KS. However, although AIDS related KS and iatrogenic KS are associated with well defined immunodeficiency, the impaired immune function in classic KS (related to 'immunosenescence', as an ageing immune system) and endemic KS (related to chronic infection and malnutrition) is not exactly characterized. In addition, KSHV can cause: I) two lymphoproliferative disorders, represented by the primary effusion lymphoma (PEL) (6) and the multicentric Castleman disease (MCD) (7), II) an inflammatory syndrome called KSHV inflammatory cytokine syndrome.
Whit regard to the clinical presentation, each recognized variant has different manifestations and different visceral involvement. It has been estimated that KS confined to the penis is uncommon and is more often observed in patients with AIDS (8), representing the first manifestation of KS in approximately 2 to 3% of HIV-positive patients. Otherwise, up to 20% of these patients may develop genital lesions in the course of the systemic disease (9,10). Even more rare primary KS of the penis may be in case of HIV seronegative patients.
The aim of this study is to describe an uncommon clinical presentation of genital KS in HIV-seronegative man and to perform a narrative literature review of the cases described to date.

Epidemiology
KS, first described by Moritz Kaposi in 1,872, is a rare neoplasm that origins from the endovascular cells in a multifocal way-This enigmatic infrequent malignant disease has since received much resonance after the AIDS epidemic in the early 1980s, with an incidence of classic KS ranged from 0.01 per 100.000 person years for the UK and 0.2 per 100.000 person years for the USA. However, currently, the incidence of KS is reported to be 200-fold higher in recipients of solid organ transplants, known as iatrogenic KS form, rather than in the general population (11). The incidence of KSHV in south Africa is very high, reaching >90% in some population, while in Europe prevalence is 20-30%, in Asia and USA is <10% (3). In the Early 1980s with the onset of AIDS emergency, one of the first sign was the rise of KSHV infections. Indeed, a rise of KS incidence of 20.000 time in general population and 300 times in AIDS patients was estimated compared to other immunosuppressed patients (12) with a higher rate for MSM (13). Moreover, with the introduction of combination antiretroviral therapy (cART) the incidence of AIDS related to KSHV decreased considerably (14).

Physiopathology
KSHV is a large double-stranded DNA herpesvirus with a protein covering by an icosahedral capsid, surrounded by tegument and enclosed in a lipid envelope derived in part from the cell membrane. Different glycoproteins in the viral envelope interact with cell type specific cellular entry receptors such as integrins (including α3β1, αVβ5 and αVβ3), the cystine-glutamate transporter xCT, heparan sulfate and the tyrosine protein kinase receptor EPHA2). KSHV can infect several different cell types, including endothelial cells, B cells, epithelial cells, dendritic cells, monocytes and fibroblasts. Once inside the cell and after uncoating the virus genome enter in the nucleus where enter in lantecy pha-se as episome and undergoes sporadic bouts of lytic reactivation (15). Virus can induce latency in human B cells and endothelial cells, as others Herpes virus. During the latent state expresses the latency locus, which includes ORF71 (who encoding viral inhibitory protein vFLIP), ORF72 (encoding vCyclin), ORF73 (encoding latencyassociated nuclear protein (LANA)), ORFK12 (encoding the kaposins, which are signalling proteins) and several microRNAs (miRNAs) (16,17). The latent genes expressed can promote tumorigenesis supporting the survival of the infected cell. Indeed, vFLIP protein activates I κB kinase 1 (IKK1) to stimulate the nuclear factor κB (NF κB) pathway to increase cell survival, viral miRNAs inhibit apoptosis. Finally, miRNAs also promote endothelial cell reprogramming, and induces the migration and invasion of endothelial cells and vFLIP promotes vascular proliferation. The reactivation from the latency is determined by different stimuli that are not well defined. During this phase, the virus induces, at first the expression of Immediate early (IE) genes than, Delayed early (DE) genes. Similar to the protein products of latency genes, the protein products of lytic genes can contribute to tumorigenesis. The products of those genes (such as vIL 6) can induce pro inflammatory and angiogenic factors, including vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) (18,19). In order to survive and to induce cell survival and cell proliferation, KSHV modulate many host cell signaling pathways, including the phosphoinositide 3 kinase (PI3K)-AKT--mTOR pathway, the mitogen activated protein kinase (MAPK) pathway and the NF κB pathway. KSHV encode also genes with the capacity to inhibit host immune respond. K3 and K5 are lytic genes that encode modulator of immune recognition 1 (MIR1) and MIR2 both of which inhibit major histocompatibility complex (MHC) class I antigen presentation to prevent the immune system. KSHV homologues of interferon regulatory factors (IRFs), viral IRFs (vIRFs), are lytic proteins that inhibit type I interferons. KSHV also encodes three CC chemokine ligands (CCLs, formerly known as vMIPs): vCCL 1 (encoded by ORFK6), vCCL2 (encoded by ORFK4) and vCCL3 (encoded by ORFK4.1), which can negatively regulate in-flammation. Finally, the KSHV K14 gene encodes for a viral OX2 (vOX2), an immunoglobulin superfamily member with homology to the cellular OX2 membrane glycoprotein (OX2, also known as CD200) that binds to the receptor CD200R and suppressed neutrophil activation, decreased CCL2 (also known as MCP1) and IL 8 production and inhibited oxidative burst in neutrophils stimulated to undergo phagocytosis.

Clinical presentation
The behavior of the disease varies from a singular lesion localized in the skin, to a fleeting extensive respiratory and gastrointestinal visceral involvement. All variants of KS cutaneous lesions usually present as multiple, pigmented, raised or flat, painless that do not blanch. Classic variant (also known as sporadic KS) is typically confined to lower limbs with few lesions. Visceral and mucosal disease is rare and usually occurs in the gastrointestinal tract. Endemic is a typical manifestation of African children often present with multiple lymph nodes with lymphoedema and a very aggressive natural history of the disease, including visceral disease. AIDS-related is characterized by multiple cutaneous lesions on the limbs, trunk and face. Mucosal lesions, such as oral lesion, are common (identified in 20% of patients) and visceral involvement is seen in 15% of patients. Related with Iatrogenic immunodeficiency, such as in organ transplantation. Often presents as cutaneous KS lesions but both mucosal and, rarely, visceral disease can occur. Finally, in MSM patients the clinical manifestations included lesions that can occur at any skin sites, usually few. Visceral and mucosal disease is rare (3). Regarding visceral involvement, organ lesions are uncommon (in one study, only 15% of 469 patients had visceral lesions upon diagnosis with AIDS related KS) (20). Gastrointestinal and pulmonary lesions are more present in AIDSrelated KS. Pulmonary lesions present with dyspnea, dry cough and sometimes hemoptysis, with or without fever, are life threatening. These lesions typically appear as a diffuse reticule nodular infiltrate and/or pleural effusion on chest radiography. Gastrointestinal lesions are usually asymptomatic, but may bleed or cause obstruction, and their presence is usually confirmed at endoscopy. However, CT scans, bronchoscopy and endoscopy are not warranted in patients unless they present symptoms indicative of visceral lesions (3). When there is clinical suspicion of KS, a biopsy sample is taken to confirm the diagnosis histologically. Pathologic diagnosis can often be made using conventional hematoxylin and eosin (H&E) and it shows some characteristic features such as, vascular proliferation in the dermis, an increased number of vessels without an endothelial cell lining, the presence of extravasated blood, spindle cells express endothelial markers and are considered to be the KS tumor cell (CD34, LYVE1 and VEGF receptor 3) (3). As concerned the therapy in patients with forms of KS when immunosuppression is potentially reversible, the first line approach is to bolster the immune system. IFNα and alitretinoin (a retinoid panagonist receptor), are approved for AIDS related KS, as KSHV directed therapy (3). Otherwise, regarding the management of genital KS, no specific therapy has been described to date.

CASE DESCRIPTION
A 71-year-old heterosexual, Caucasian man, referred to our department for the presence of penile neoformation appeared from at least 6 months. At the clinical examination, a 0.6mm x 0.6mm x 0.3mm red painless radish nodule hemangioma-like was found on the gland near the frenulum (Figures 1A and  1B). He did not complain penile bother nor there were palpable inguinal lymph nodes. His past medical history reveled only hypertension and hyperuricemia under treatment. The urine analysis and blood laboratory tests showed normal results. The urine culture was negative for Neisseria Gonorrhoeae, Trichomonas Vaginalis, Ureaplasma Urealitycum, Mycoplasma hominis, Mycoplasma Genitalium, Clamydia Trachomatis. The enzyme-linked immunoassorbant assay (ELISA) sierology was negative for Troponema pallidum and HIV 1-2 infections. A complete surgical excisional biopsy of the lesion   (45)). The most frequently involved site is the glans, sometimes in associations with swelling and lymphatic edema due to massive involvement and the most common manifestation is a nodular reddish or purplish lesion, single or multiple, sometimes ulcerated too. Lesions may also involve the foreskin, the coronal sulcus, or the meatus. In this last case urinary obstructive symptoms may occur. The involvement of the shaft is rare, usually being related to lesions located on the glans or coronal sulcus. Notably, the lesion observed in our patient was a single red radish pedunculated hemangioma-like lesion of the gland next to the frenulum. To our knowledge, this atypical clinical presentation is similar to others described in literature. Indeed, other comparable lesions described in literature varied from a red purple nodule, or radish 5mm papule in diameter of gland to a 1mm nodule next of the meatus. Nevertheless, it remains a rather infrequent manifestation because of its appearance, that could simulate a benign pedunculated lesion of vessels. According to other cases in literature, our case refers to an immunocompetent HIV-seronegative patient. Therefore, similar cases although rare, could not be infrequent. However, the management of   patients with KS should include: exams to exclude ongoing infectious diseases, assessment of patient's immunological status, histological analysis following surgical biopsy and visceral involvement evaluation through CT or ultrasounds, despite it is not necessary in asymptomatic patients, according to others studies (3). In our case, we managed it with complete surgical excision of the lesion, as described by other authors (24, 26, 28, 30, 31, 35, 36, 38-40, 43, 44, 47, 49), with a disease recurrence in five cases (24,30,31,36,39) from a period of about 1-2 years. Other approaches described in literature could include radiotherapy (25,29,37,42), subtotal circumcision associated with biopsy (45), cryotherapy associated with 5% Imiquimod cream (21), excisional biopsy associated with IFNα (32), biopsy with chemotherapy (39), CO2 (48), biopsy with radiotherapy (46). Furthermore, in five cases no therapy was performed (22,23,33,34), two of them for the spontaneous regression of the disease (33,34).

Literature review
The clinical course of primary penile KS is variable and no standardized follow-up exists to date. In general, local recurrences are rare if the primary tumor is completely removed. In one of them (33) the authors refer recurrence of a new penis lesion after seven months, then after one year two lesions on both legs and one on conjunctiva. Other cases of recurrences occurred for therapy with biopsy with IFNα(32) and with CO2 (48). Respect the management of recurrence, it was described only a recurrence after excisional biopsy (24) in which case it was treated with a new biopsy with radiotherapy, with no recurrence. In our patient, at 6-months from surgery there are no signs of disease progression, although it is a too short follow-up period.

CONCLUSION
New-onset apparently benign lesions of penis in immunocompetent patients, even in absence of risk factors for sexually transmitted diseases, should be always investigated, because it could represent the first manifestation of primary KS in which penis could be the only isolated clinical presentation. The surgical management could represent a good therapeutic option, leading to disease clinical resolution with no further recurrence, thus providing histological diagnosis.