Systemic T-cell and NK-cell Lymphomas Involving the Skin



Systemic T-cell and NK-cell Lymphomas Involving the Skin


Aaron Auerbach, MD, PhD





Key Facts


Terminology



  • Systemic T-cell or NK-cell lymphoma that has spread to the skin


  • Morphology of primary and secondary skin lymphomas are similar


Etiology/Pathogenesis



  • Epstein-Barr virus infection in some lymphomas


Clinical Issues



  • Often multiple lesions, less often single lesion


  • Most commonly in adults


  • Usually much worse prognosis than primary cutaneous lymphoma


  • Frequently aggressive chemotherapy, contrary to many primary cutaneous T-cell lymphomas, which are treated with more conservative therapy


Microscopic Pathology



  • Peripheral T-cell lymphoma, unspecified, includes any T-cell lymphomas that do not fit into a better defined subtype of T-cell lymphoma


  • Systemic ALK(+) anaplastic large cell lymphoma (ALCL): Often large atypical tumor cells in dermis, sometimes hallmark cells with multiple (horseshoeshaped nuclei)


  • Angioimmunoblastic T-cell lymphoma presents as superficial perivascular T-cell infiltrates with increased reactive inflammatory cells and high endothelial venules


  • Extranodal NK/T-cell lymphoma, nasal type, presents as medium to large cells with necrosis and angiocentricity that express T-cell and NK markers and are EBER(+)







This is an example of a systemic anaplastic large cell lymphoma (ALCL) secondarily involving the skin. The lymphoid infiltrate diffusely fills the superficial and deep dermis.






At higher power, tumor cells in systemic ALCL are large and pleomorphic appearing image. Mitotic figures are seen image.


TERMINOLOGY


Abbreviations



  • Systemic T-cell lymphoma (STCL) involving skin


Synonyms



  • Secondary cutaneous T-cell lymphoma


Definitions



  • T-cell or NK-cell lymphoma that has spread to the skin as a secondary site of disease



    • Lymphoma originates systemically, but involves skin


    • Morphology of primary and secondary skin lymphomas are similar



      • Clinical behavior and treatment of each is divergent, however


ETIOLOGY/PATHOGENESIS


Depends on Type of NK/T-cell Lymphoma



  • Can be therapy related


  • Epstein-Barr virus infection in some lymphomas



    • Including angioimmunoblastic T-cell lymphoma and extranodal NK/T-cell lymphoma, nasal type


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Secondary cutaneous lymphomas make up 50% of all cutaneous lymphomas, excluding mycosis fungoides


    • Secondary T-cell lymphoma in skin is less common than systemic B-cell lymphoma in skin


    • 20-30% of peripheral T-cell lymphoma, unspecified, has cutaneous involvement



      • Represents ˜ 14% of all secondary skin lymphomas


    • ˜ 50% of angioimmunoblastic T-cell lymphoma (AILT) have cutaneous lesions


    • ˜ 8-20% of extranodal NK/T-cell lymphoma, nasal type involve skin


  • Age



    • Any age, but mostly adults



      • Systemic anaplastic large cell lymphoma (ALCL) displays a bimodal distribution that includes children, whereas primary cutaneous ALCL is primarily found in adults


  • Gender



    • Occurs in both males and females


Presentation



  • Often multiple lesions, less often single lesions



    • Usually tumors or nodules


    • Any cutaneous site, no site of predilection


    • Skin involvement may present at time of initial diagnosis or develop later


Treatment



  • Usually adjuvant therapy



    • Frequently aggressive chemotherapy, contrary to many primary cutaneous T-cell lymphomas, which are treated with more conservative therapy


Prognosis



  • Depends on type of T cell, but usually poor prognosis



    • Higher stage than primary cutaneous lymphoma


    • Usually much worse prognosis than primary cutaneous lymphoma


  • ALK(−) ALCL has a worse prognosis than primary cutaneous ALCL or systemic ALK(+) ALCL


MICROSCOPIC PATHOLOGY


Histologic Features



  • Morphology and immunophenotype sometimes identical to systemic disease



  • Peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS)



    • All T-cell lymphomas that do not fit into a better defined subtype of T-cell lymphoma



      • Other types of T-cell lymphoma must 1st be excluded


    • Wide variety of morphologic appearances


    • Usually an atypical nodular or diffuse dermal T-cell infiltrate sparing epidermis, which may extend to subcutis



      • Medium to large T cells, often with markedly pleomorphic nuclei


      • Sometimes immunoblastic T cells or Reed-Sternberg-like T cells


    • Background reactive infiltrate including small lymphocytes, plasma cells, and eosinophils


    • Can be confused with infection, granuloma annulare, lupus or dermatomyositis, panniculitis and vasculitis


  • Systemic ALK(+) anaplastic large cell lymphoma (ALCL)



    • 30% involve skin


    • Often large atypical tumor cells in dermis, sometimes hallmark cells with multiple (horseshoeshaped) nuclei


    • Usually no epidermotropism


    • Can involve lymphatic spaces


  • Systemic ALK(−) anaplastic large cell lymphoma



    • Same histology as systemic ALK(+) ALCL but considered a different disease than primary cutaneous ALCL


  • Angioimmunoblastic T-cell lymphoma (AITL)



    • Superficial perivascular infiltrates with lymphocytes, eosinophils, often plasma cells and histiocytes


    • Less often, may show more sheet-like, destructive dermal T-cell infiltrates


    • Increased numbers of high endothelial venules


  • Extranodal NK/T-cell lymphoma, nasal type

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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Systemic T-cell and NK-cell Lymphomas Involving the Skin

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