Kaposi Sarcoma
HHV-8 associated, classic, endemic, and iatrogenic KS
Clinical FeaturesClick to collapse
Typical Presentation
Kaposi sarcoma (KS) is a multifocal malignancy of endothelial cells that presents with characteristic purpuric, red, or brown macules, papules, and plaques. Four types are described: HIV-associated (epidemic), classic, iatrogenic (transplant-associated), and endemic [1]. Classic KS generally involves indolent cutaneous lesions, often of the lower extremities, which may wax and wane or slowly progress over years to decades; it is most common in people of Mediterranean, Eastern European, Middle Eastern, and/or Jewish origins, with a mean age of 74 years at diagnosis and a male-to-female ratio of 7–15:1 [1,3]. HIV-associated KS, when immunosuppression is advanced, is more aggressive and more likely to involve viscera, mucosa, and lymph nodes and to cause lymphedema; however, it can also occur in PWH with normal CD4+ counts and undetectable HIV viral load, typically with more limited disease [MS-3]. Endemic KS occurs in children and younger adults (<40 years) of equatorial Africa, is more aggressive than classic KS, and may involve viscera, bone, and/or lymph nodes, with a male predominance of 10–17:1 [1]. Iatrogenic KS appears 2–8 months after initiation of immunosuppressive therapy (e.g., for organ transplant or other reasons), is 2–3 times more common in males, and can be aggressive but often responds to cessation or reduction of immunosuppression [1]. Lymphedema is a common complication and may also be a predisposing factor; it can be caused by nodal involvement or involvement of lymphatic vessels [MS-6]. Hyperkeratotic variants with verrucous changes are notably associated with chronic and severe KS-associated lymphedema [MS-6].
Symptoms
Cutaneous lesions
Painless or sometimes pruritic purpuric, red, or brown macules, papules, plaques, nodules (sometimes pedunculated), and bullae. Large plaques may form from coalescence of smaller plaques or nodules and may ulcerate or develop bullae.
Lymphedema
Swelling of extremities, often lower limbs, due to lymphatic involvement. Associated with increased risk of cellulitis and deep tissue infections.
Oral lesions
Purple or red macules, plaques, or nodules on the palate, gingiva, or tongue. May cause pain, bleeding, or difficulty eating.
Visceral involvement
Gastrointestinal (GI) KS may cause nausea, vomiting, abdominal pain, melena, or blood in stool. Pulmonary KS may cause dyspnea, cough, hemoptysis. Nodal KS may cause lymphadenopathy.
Constitutional symptoms
Fever, night sweats, weight loss, fatigue – may indicate KSHV-associated inflammatory cytokine syndrome (KICS) or multicentric Castleman disease (MCD).
Signs
Skin lesions
Purpuric, red, or brown macules, papules, plaques, nodules. Hyperpigmented macules (lacking palpable change) are common after regression due to residual hemosiderin pigmentation (not active disease). Histologic subtypes include anaplastic, telangiectatic, lymphedematous, hyperkeratotic, keloidal, micronodular, pyogenic granuloma-like, ecchymotic, and intravascular variants [MS-6].
Oral lesions
Located on palate, gingiva, buccal mucosa, tongue. May be nodular or plaque-like.
Lymphedema
Pitting or non-pitting edema of extremities, often unilateral or asymmetric. Hyperkeratotic changes may accompany chronic lymphedema.
Lymphadenopathy
Palpable lymph nodes, often in cervical, axillary, or inguinal regions. May be bulky.
Visceral signs
Hepatosplenomegaly, ascites, pleural effusion, pulmonary rales, or signs of GI bleeding.
Red FlagsClick to collapse
Rapid development of new or enlarging KS lesions after initiation of antiretroviral therapy (ART) – may indicate immune reconstitution inflammatory syndrome (KS-IRIS) [KS-C].
Unexplained fevers, night sweats, weight loss, or diarrhea persisting >2 weeks ('B' symptoms) – poor prognostic S1 criterion and may indicate KICS or MCD [KS-A 1 of 2].
New or worsening lymphedema, especially with erythema or pain – may indicate KS progression or cellulitis.
Dyspnea, cough, or hemoptysis – may indicate pulmonary KS involvement; requires urgent chest CT and bronchoscopy [KS-1].
Gastrointestinal bleeding, melena, or unexplained anemia – may indicate GI KS; requires endoscopy/colonoscopy [KS-1].
Severe cytopenias, liver/kidney dysfunction with lymphadenopathy – may indicate MCD or KICS [MS-5].
Altered mental status, neuropathy, or cachexia – may be features of KICS [KS-1 footnote f].
Life-threatening IRIS (marked lesional swelling, increased tenderness, peripheral edema) occurring within 3–6 months of ART initiation [KS-2 footnote j].
Rapid progression during observation – indication for initiation of therapy [KS-2].
Use of glucocorticoids in any formulation (including topical, inhaled, intra-articular) may cause KS flare even in remote sites; life-threatening exacerbations have been reported [KS-B].
InvestigationsClick to collapse
Diagnostic
Biopsy (skin punch, incisional, or excisional) with histopathology review by pathologist with expertise in KS
Gold standard for diagnosis. Adequate tissue and immunophenotyping required.
Immunohistochemistry panel: KSHV (HHV-8) LANA-1
Essential to confirm diagnosis; KSHV infection present in 95–98% of KS [2,3].
IHC: CD31 and CD34 (if unclear vascular origin)
Useful in certain circumstances to confirm vascular origin when morphology is ambiguous.
Biopsy of nodal or visceral sites (if coexisting disorder suspected)
Encouraged if infection, lymphoma, or MCD is suspected.
Cytology and flow cytometry of effusion fluid (if present)
To evaluate for coexisting primary effusion lymphoma (PEL).
Staging
History and physical examination (complete skin, oral, lymph node exams; evaluation of edema)
Essential for staging and assessment of disease extent.
Photography of oral, conjunctival, and cutaneous lesions (with reference unit of measure)
For evaluation and monitoring of extent of disease over time.
Complete blood count (CBC) with differential and comprehensive metabolic panel (CMP)
Baseline assessment for cytopenias, organ function, and monitoring during therapy.
HIV screening and diagnostic testing (if not known HIV-positive)
Essential to identify HIV-associated KS; all KS patients should be tested.
CD4+ T-cell count and HIV viral load (if HIV-positive)
Assess immune function and HIV control; staging I0/I1 based on CD4 count.
Pregnancy testing (if chemotherapy or RT planned and patient of childbearing potential)
To avoid harm to fetus from anticancer therapy.
Stool hemoccult and/or chest x-ray (as clinically indicated, e.g., advanced disease)
Screen for occult GI bleeding or pulmonary involvement.
Chest CT with contrast and bronchoscopy (if unexplained pulmonary symptoms or abnormal chest x-ray)
Evaluate for pulmonary KS or opportunistic infections.
Abdomen/pelvis CT with contrast or MRI with and without contrast and EGD/colonoscopy (if GI symptoms or positive hemoccult)
Evaluate for GI KS or other pathology.
CT scan or FDG-PET/CT scan and/or lab workup (if concerns for coexisting KICS, MCD, or KSHV+ lymphoma)
Detect hypermetabolic lymphadenopathy or visceral involvement; FDG-PET/CT can assess whole-body disease.
Transthoracic echocardiogram (if anthracycline planned or suspected pericardial effusion)
Assess baseline cardiac function; monitor for cardiotoxicity.
Biopsy of lymphadenopathy (excisional preferred)
To differentiate MCD (requires histology) from KS nodal involvement or other diagnoses.
Biomarkers
C-reactive protein (CRP)
Marker of inflammation; useful when KICS or MCD suspected.
KSHV serum viral load
Elevated during flares of MCD (≥4 log) and KICS; undetectable/low during remissions.
Serum protein electrophoresis (SPEP)
Evaluate for paraproteinemia associated with MCD.
Interleukin-6 (IL-6) and/or IL-10
Cytokines driving inflammation in KICS/MCD.
StagingClick to collapse
AIDS Clinical Trials Group (ACTG) TIS staging system adapted from Krown SE, Metroka C, Wernz JC. J Clin Oncol 1989;7:1201-1207 [KS-A 1 of 2].
T Categories
| Stage | Description |
|---|---|
| T0 (Good risk) | Tumor confined to skin and/or lymph nodes and/or minimal oral disease (non-nodular KS confined to palate). |
| T1 (Poor risk) | Tumor-associated edema or ulceration; extensive oral KS; gastrointestinal KS; KS in organs other than lymph nodes. |
Stage Groupings
| Group | Criteria | Clinical Meaning | Five Yr Survival | Treatment Intent |
|---|---|---|---|---|
| T0I0S0 | T0 + CD4 ≥150/μL + no history of OI/thrush, no B symptoms, KPS ≥70. | Good risk in all three categories. Best prognosis. | Approximately 88% 3-year survival (Nasti et al., 2003) [MS-7]. | Limited cutaneous disease: observation with ART for PWH; local therapy if symptomatic. |
| T1I0S0 | T1 (any poor risk tumor factor) but good immune and systemic status. | Advanced disease by tumor criteria but preserved immune function and no systemic illness. 3-year survival 80% [MS-7]. | 80% 3-year survival. | Systemic therapy with ART for PWH. |
| T0I1S0 | Good tumor but CD4 <150/μL. | Poor immune status may increase risk of progression and IRIS. | 81% 3-year survival [MS-7]. | ART optimization; may need systemic therapy if progressive or symptomatic. |
| T1S1 (any I) | T1 + S1 (history of OI/thrush, B symptoms, KPS <70, or other HIV-related illness). Often also I1. | Worst prognosis group; combined poor tumor and systemic status. Median survival significantly reduced. | 53% 3-year survival [MS-7]. | Immediate systemic therapy with ART for PWH; supportive care for medical optimization. |
| T0S0 (any I) | Good tumor and systemic status regardless of CD4 (I stage less prognostic on ART). | Limited disease; good prognosis. | 88% 3-year survival [MS-7]. | Observation or local therapy; ART for PWH. |
Staging Pearls
- I stage (CD4 count) has less prognostic value than T or S stages in patients on ART [KS-A 1 of 2, MS-7].
- T1S1 confers the worst prognosis: 3-year survival 53% vs. 88% for T0S0 [MS-7].
- Management is primarily stratified by limited cutaneous vs. advanced disease (T1, extensive T0 cutaneous, or nodal disease) [KS-1 footnote e].
- B symptoms defined as unexplained fever, night sweats, >10% involuntary weight loss, or diarrhea persisting >2 weeks [KS-A 1 of 2].
- Response criteria (ACTG) define CR as absence of detectable disease including tumor-associated edema for ≥4 weeks; PR requires ≥50% decrease in lesions or flattening of ≥50% raised lesions [KS-A 2 of 2].
- Residual hyperpigmented macules after treatment represent hemosiderin 'tattoo' effect, not active disease; biopsy may show siderophages without tumor cells [MS-8].
Management PrinciplesClick to collapse
Kaposi sarcoma (KS) is a multifocal malignancy of endothelial cells universally associated with KSHV infection. Four types exist: HIV-associated, classic, iatrogenic/transplant-associated, and endemic. Immunosuppression is a key pathogenic factor. Treatment philosophy focuses on disease control rather than cure, as KSHV persists lifelong and individual lesions may represent distinct clones. Management emphasizes optimization of immune function, avoidance of additional immunosuppression (especially glucocorticoids in any formulation), and use of the least toxic therapy appropriate to disease extent. Complete remissions are rare in advanced disease; goals are symptom reduction, reversal of lymphedema, and preservation of organ function.
Observation and immune optimization
PWH with asymptomatic limited cutaneous disease cosmetically acceptable; patients without HIV with asymptomatic limited disease
For PWH: start/continue ART, reassess within 4 weeks for IRIS. For non-HIV: observation until symptomatic or progressive. Remissions or stable disease may occur with ART and immune function optimization alone [KS-B; MS-10].
Minimally invasive symptom control
Patients with symptomatic or cosmetically bothersome limited cutaneous disease
Use least toxic therapy: local therapy (topical alitretinoin, intralesional vinblastine/bleomycin, cryotherapy, marginal excision, electrodessication and curettage), RT, or limited cycles (3-6) of systemic therapy. For PWH, concurrent ART is critical. A limited number of systemic therapy cycles may be sufficient for those initiating or re-initiating ART [KS-2; KS-B].
Systemic disease control
Patients with advanced symptomatic disease (T1, extensive T0, nodal, visceral)
Systemic therapy is first-line (preferred: liposomal doxorubicin for non-transplant KS; paclitaxel as other recommended; sirolimus for transplant KS). RT reserved when systemic therapy not feasible. For PWH, ART must be continued/initiated. Goals: reduce/reverse symptoms, lymphedema, organ threat. Treatment continues until unacceptable toxicity or plateau; no maintenance beyond 2 cycles after plateau [KS-3; KS-B].
KICS management
Patients with KSHV-associated inflammatory cytokine syndrome (KICS)
First-line: liposomal doxorubicin + rituximab (preferred) or alternative KS-directed therapy + rituximab. In mild cases, KS-directed therapy alone may suffice. For transplant recipients, maximize sirolimus and minimize other immunosuppression. Refractory: add anti-IL-6 therapy (tocilizumab or siltuximab). Continue KS-directed therapy for ≥3 months after stopping rituximab [KICS-1].
Co-management by oncology and HIV specialists is recommended for the duration of therapy. Oncology and HIV pharmacists should review proposed cancer therapy, supportive care, and ART for DDIs and overlapping toxicities. Involvement of dermatology, medical oncology, hematology, and primary HIV care is appropriate during surveillance. Lymphedema specialist referral is recommended for patients with lymphedema. Collaboration with a pharmacist regarding immunosuppression options is advised for patients requiring immunosuppression [KS-B; KS-4; KS-1].
Performance status (Karnofsky) is part of the TIS staging system (S0 ≥70, S1 <70). For advanced disease, if poor performance status is due to KS itself, systemic therapy should be considered as it may improve performance status. If performance status precludes upfront chemotherapy, reversible medical issues (active infection, high HIV viremia) should be addressed to enable systemic therapy. RT or best supportive care may be used if performance status remains poor [KS-3; KS-A 1 of 2].
Management PathwaysClick to collapse
Branching: HIV status, Symptom status, Cosmetic acceptability
Branching: HIV status, Previous therapy response
Branching: Eligibility for systemic therapy, HIV status, Response to therapy
Branching: Severity, Transplant status, Response to initial therapy
Pretreatment EvaluationClick to collapse
Essential
Useful in Selected Cases
SurgeryClick to collapse
Limited role; used for local control of small, symptomatic lesions in patients with limited cutaneous disease. Wide excision with negative margins is not indicated as it does not prevent new lesions. For larger lesions, radiotherapy is preferred over excision when systemic therapy is not feasible.
Marginal excision is appropriate for small lesions; wide excision is not indicated.
Surgery does not prevent occurrence of future lesions because individual KS lesions are distinct clones arising from immunosuppression and KSHV persistence.
Electrodesiccation and curettage may be considered for small lesions.
For plantar and palmar surfaces, excision or intralesional chemotherapy should be approached with caution due to toxicity and functional concerns.
Procedures
Marginal excision
Local control of small, symptomatic lesions in limited cutaneous disease.
Electrodesiccation and curettage
Small, symptomatic lesions.
Radiation TherapyClick to collapse
Used for limited cutaneous disease that is symptomatic/cosmetically bothersome, and for palliation in advanced disease when systemic therapy is not feasible. Also for relapsed/refractory disease. RT is radioresponsive with CR rates 60-93%. Systemic therapy is preferred over RT for first-line and relapsed/refractory disseminated disease whenever feasible.
Principles
- For most skin lesions, electrons or superficial x-rays achieve optimal dosimetry. For deeper/larger lesions, IMRT with or without image guidance may be useful.
- Bolus may be necessary for adequate skin dose.
- Caution with plantar/palmar surfaces; high doses may impair wound healing, especially with lymphedema.
- Risk of secondary cancer, severe/worsening lymphedema, and long-term wound healing complications; mitigate with lower-dose regimens.
- For advanced cutaneous disease, RT reserved for when systemic therapy not feasible, goal palliation or short-term disease management until systemic therapy can be delivered.
- Treatment responses may be delayed in significant lymphedema.
Dose Frameworks
| Name | Total Dose | Dose Per Fraction | Fractions | Schedule | Indication |
|---|---|---|---|---|---|
| Single fraction | 6-8 Gy | 6-8 Gy | 1 | Single fraction | Small, superficial lesions; palliative situations. |
| Hypofractionated | 20 Gy | 4 Gy | 5 | Daily fractions | Effective for KS; equivalent to 24 Gy/12 fractions. |
| Standard fractionation (1) | 24 Gy | 2 Gy | 12 | Daily fractions | Standard regimen. |
| Standard fractionation (2) | 30 Gy | 2-3 Gy | 10-15 | Daily fractions | More extensive or deeply invasive lesions; durable local response desired. |
| Extended fractionation | 40 Gy | 2 Gy | 20 | Daily fractions | When more durable response needed; may be used for oral cavity with adjacent radiosensitive structures. |
Approaches
| Name | Dose Fractionation | Concurrent Chemotherapy | Indication | Key Trial | Toxicities |
|---|---|---|---|---|---|
| Electron or superficial x-ray therapy | Any of the above regimens depending on indication | Not typically given concurrently; sequential if needed. | Most skin lesions; minimize dose to underlying structures. | Singh NB et al. Radiother Oncol 2008;88:211-216 [KS-E reference 1] | Dermatitis, oral mucositis, lymphedema exacerbation, long-term wound healing issues, secondary cancer risk. Risk increased with pre-existing lymphedema. |
| IMRT with or without image guidance | Fractionated regimens preferred for large/deep lesions or near critical structures | None specified | Larger, deeper disease, or disease adjacent to critical structures. | No specific trial cited; expert consensus. | Same as above; potential for higher conformality reducing toxicity. |
Systemic TherapyClick to collapse
Systemic therapy is the mainstay for advanced symptomatic KS and an option for limited cutaneous disease. First-line options differ by transplant status. For non-transplant KS, liposomal doxorubicin is preferred; paclitaxel is other recommended. For transplant KS, sirolimus alone may be sufficient; liposomal doxorubicin and paclitaxel are other recommended. After first-line failure, subsequent options include nivolumab, pembrolizumab, pomalidomide (preferred); and in certain circumstances: albumin-bound paclitaxel, bortezomib, etoposide, gemcitabine, imatinib, ipilimumab+nivolumab, lenalidomide, sirolimus (transplant), thalidomide (IRIS), vinorelbine. Corticosteroid pre-medication should generally be avoided except for prior reaction. An FDA-approved biosimilar is appropriate substitute for any recommended biologic. ICIs should not be used in MCD or KICS; use with caution if history of KSHV-associated diseases.
Key Regimens
Treatment Response AssessmentClick to collapse
Title
Response Definitions for Kaposi Sarcoma (adapted from ACTG Oncology Committee criteria, 1989)
Timing
Response assessments should be performed after each treatment cycle or as clinically indicated. For patients on observation, reassess at intervals based on disease stability. For PWH on ART alone, reassess within 4 weeks to monitor for IRIS. Long-term surveillance is life-long.
Response Logic
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Complete response (CR): Absence of any detectable residual disease, including tumor-associated (local) edema, persisting for at least 4 weeks. Patients with prior visceral disease should have restaging with appropriate endoscopic or radiographic procedures relevant to sites involved at baseline. Residual non-palpable macular pigmentation (hemosiderin tattooing) is not active disease.
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Partial response (PR): No new mucocutaneous lesions, visceral sites of involvement, or appearance/worsening of tumor-associated edema or effusions; AND one of: (1) ≥50% decrease in number of all pre-existing lesions lasting ≥4 weeks; OR (2) complete flattening of ≥50% of all previously raised lesions; OR (3) ≥50% decrease in sum of products of largest perpendicular diameters of at least 5 measurable lesions. Note: If residual tumor-associated edema or effusion but otherwise meets CR criteria, classify as PR.
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Stable disease (SD): Any response not meeting criteria for PD or PR.
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Progressive disease (PD): >25% increase in size of pre-existing lesions and/or appearance of new lesions/sites, and/or change in character from macular to plaque-like or nodular of >25%. New or increasing tumor-associated edema or effusion constitutes PD.
Imaging Recommendations
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Imaging should be directed by symptoms or findings concerning for visceral or bone involvement, or for coexisting KICS, MCD, or KSHV+ lymphoma. Can include whole-body FDG-PET/CT.
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For patients with known visceral disease at baseline, appropriate endoscopic or radiographic procedures (CT, MRI, bronchoscopy, EGD, colonoscopy) should be repeated to confirm CR.
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In patients with effusions, encourage cytology and flow cytometry to evaluate for PEL.
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For surveillance: if signs and symptoms concerning for visceral involvement or prior to new therapy for progression/refractory disease, perform imaging as clinically indicated (chest CT with contrast, abdomen/pelvis CT or MRI, FDG-PET/CT as needed).
Biopsy Or Salvage Logic
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If progressive, relapsed, or refractory disease suspected, consider biopsy of lesions to distinguish active KS from post-inflammatory pigment or mimickers (e.g., bacillary angiomatosis, cryptococcosis).
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If KS confirmed, evaluate for inadequate HIV control as contributing factor; address possible change in ART with HIV specialist.
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If after initial response, KS relapses or progresses, repeat use of previously effective therapy may be considered, particularly if response was durable (≥3 months) and well tolerated.
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For patients on observation with rapid progression, initiate therapy as indicated per disease state.
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In transplant KS, if sirolimus alone insufficient, add systemic therapy.
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For KICS, if inflammatory markers flare after rituximab cessation, resume rituximab; consider repeating cytology of effusions and biopsy of lymphadenopathy if lymphoma suspected.