Kaposi Sarcoma



Kaposi Sarcoma


Thomas Mentzel, MD





Key Facts


Terminology



  • Locally aggressive endothelial neoplasm associated with human herpes virus 8


Clinical Issues



  • Most typical site of involvement is skin


  • Mucosal membranes, lymph nodes, and visceral organs may be affected


  • 4 main different clinical and epidemiologic forms are recognized



    • Classical indolent form


    • Endemic African form


    • Iatrogenic form


    • AIDS-associated form


  • Prognosis depends on epidemiological-clinical type


Macroscopic Features



  • Skin lesions range in size from very small to several centimeters


Microscopic Pathology



  • Histologic features of all forms of KS do not differ


  • KS shows different stages of disease


  • Patch stage of KS



    • Increased vascular spaces in reticular dermis


    • Scattered lymphocytes and plasma cells


  • Plaque stage of KS



    • More extensive vascular proliferation


  • Nodular stage of KS



    • Well-circumscribed, cellular nodules


    • Intersecting cellular fascicles of spindled tumor cells






Clinical photograph shows a case of classical Kaposi sarcoma arising in an elderly man who presented with multiple nodular lesions.






Clinical photograph shows an HIV-positive patient who developed multiple small lesions on the trunk and lower extremities.


TERMINOLOGY


Abbreviations



  • Kaposi sarcoma (KS)


Definitions



  • Locally aggressive endothelial neoplasm associated with human herpes virus 8 (HHV8)


ETIOLOGY/PATHOGENESIS


Infectious Agents



  • Associated with HHV8



    • HHV8 is found in all forms of disease


    • HHV8 is detected in peripheral blood


CLINICAL ISSUES


Site



  • Most typical site of involvement is skin


  • Mucosal membranes, lymph nodes, and visceral organs may be affected


Natural History



  • 4 main different clinical and epidemiologic forms are recognized



    • Classical indolent form



      • Occur predominantly in elderly men of Mediterranean/East European descent


      • Purplish, reddish-blue, dark brown plaques and nodules


      • Usually in distal extremities


    • Endemic African form



      • Occurs in middle-aged adults and children in equatorial Africa


      • Patients are not infected by HIV


    • Iatrogenic form



      • Occurs in patients treated by immunosuppressive agents


    • AIDS-associated form



      • Occurs in patients infected by HIV-1


      • Most aggressive form


      • Lesions are seen on face, genitals, lower extremities


      • Mucosal membranes, lymph nodes, and visceral organs are frequently involved


Treatment



  • Options, risks, complications



    • Chemo- &/or radiotherapy


    • Cryotherapy may be useful


  • Surgical approaches



    • Surgical treatment of single lesions only


Prognosis



  • Classical indolent form



    • Indolent clinical course


    • Lymph node and visceral organ involvement occurs only infrequently


  • Endemic African form



    • Protracted clinical course


    • Lymphadenopathic form is progressive and highly lethal


  • Iatrogenic form



    • May resolve entirely after withdrawal of immunosuppressive treatment


  • AIDS-associated form



    • Most aggressive type of KS


  • Prognosis depends on epidemiological-clinical type of KS


  • Prognosis is strongly related to stage of disease


  • Prognosis is strongly related to additional infectious diseases


MACROSCOPIC FEATURES


General Features



  • Skin lesions range in size from very small to several centimeters




  • Hemorrhagic nodules of variable size in visceral organs and lymph nodes


MICROSCOPIC PATHOLOGY


Histologic Features



  • Histologic features of all forms of KS do not differ


  • KS shows different stages of disease


  • Patch stage of KS



    • Increased vascular spaces in reticular dermis



      • Papillary dermis is not involved in early stages


    • Vascular spaces dissect collagen bundles


    • Perivascular and periadnexal growth of vascular spaces


    • Vascular spaces are lined by flat, uniform endothelial cells


    • Scattered lymphocytes and plasma cells


    • Extravasated erythrocytes and hemosiderin deposits


  • Plaque stage of KS



    • More extensive vascular proliferation


    • Denser inflammatory infiltrate


    • Hyaline globules representing destroyed erythrocytes may be found


  • Nodular stage of KS



    • Well-circumscribed, cellular nodules


    • Intersecting cellular fascicles of spindled tumor cells


    • Slit- and sieve-like spaces containing erythrocytes


    • Mild cytologic atypia


    • Numerous mitoses


  • Some patients develop lymphangiomatous lesions &/or hemangiomatous lesions


Cytologic Features



  • Bland flat and spindled endothelial tumor cells


DIFFERENTIAL DIAGNOSIS


Hobnail Hemangioma



  • Solitary vascular lesions


  • Biphasic growth



    • Dilated vessels in superficial parts, narrow vascular spaces in deeper parts of dermis


  • Hobnail endothelial cells


  • HHV8(-)


Capillary Hemangioma



  • Different clinical findings


  • Lobular growth of narrow capillaries


  • HHV8(-)


Lymphangioma



  • Common pediatric lesions


  • Rather well-circumscribed lesions


  • Dilated vascular spaces


  • Usually no inflammatory infiltrate


  • HHV8(-)


Progressive Lymphangioma (Benign Lymphangioendothelioma)



  • Slowly growing, solitary, plaque-like lesions


  • No spindled tumor cells


  • No prominent inflammatory infiltrate


  • HHV8(-)


Spindle Cell Hemangioma

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Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Kaposi Sarcoma

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