Cutaneous Gamma-Delta T-cell Lymphoma



Cutaneous Gamma-Delta T-cell Lymphoma


Aaron Auerbach, MD, PhD





Key Facts


Terminology



  • T-cell lymphoma of mature γδ cells


  • Separately classified from SPTCL in WHO (2008)


Clinical Issues



  • Hemophagocytic syndrome in 45%


  • Poor prognosis


  • Treated with multiagent chemotherapy


Macroscopic Features



  • Skin nodules with ulceration


Microscopic Pathology



  • 3 patterns of disease: Epidermotropic, dermal, and subcutaneous



    • Malignant T cells rim around adipocytes


    • Prominent karyorrhexis/apoptosis and angioinvasion


Ancillary Tests



  • Immunohistochemistry: TCRδ1(+), βF1(−), CD56(+), CD4(−), CD8(−), EBER(−), cytotoxic markers (+)


  • T-cell receptor gene rearrangement


Top Differential Diagnoses



  • Subcutaneous panniculitis-like T-cell lymphoma



    • Panniculitis, but not in dermis or epidermis; lacks ulceration; TCRδ1(−), βF1(+)


    • Much better prognosis than CGDTCL


  • Peripheral T-cell lymphoma, not otherwise specified


  • Lupus profundus panniculitis



    • Similar inflammation in the subcutis in panniculitic pattern


    • Lobular panniculitis, but contains plasma cells and germinal centers, unlike CGDTCL







Cutaneous γδ T-cell lymphoma shows a large raised lesion with ulcer and satellite lesions. (Courtesy C. Sander, MD.)






Primary cutaneous γδ T-cell lymphoma involves the epidermis, dermis image, and subcutaneous tissue image with the most extensive disease in the dermis and subcutis. (Courtesy L. J. Medeiros, MD.)


TERMINOLOGY


Abbreviations



  • Cutaneous gamma-delta T-cell lymphoma (CGDTCL)


Synonyms



  • Subcutaneous panniculitis-like T-cell lymphoma with γδ cells


Definitions



  • T-cell lymphoma arising in the skin, which is composed of cytotoxic γδ T cells



    • Does not include subcutaneous panniculitis-like T-cell lymphoma composed of αβ cells



      • May encompass mucocutaneous γδ cell T-cell lymphoma, but further study is needed


ETIOLOGY/PATHOGENESIS


Immunosuppression or Dysregulation of T Cells



  • Found in many of the patients


Chronic Antigenic Stimulation



  • Speculative, but possibly involved in pathogenesis


Cell of Origin



  • γδ T cells



    • Involved with mucosal and epithelial immune system function


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare tumor, < 100 cases reported in literature



      • < 1% of all cutaneous T-cell lymphomas


  • Age



    • Commonly adults


  • Gender



    • No gender preponderance


Site



  • Mostly extremities



    • Sometimes mucosal sites, where normal γδ T cells are found


    • Metastasis common



      • Spread to lungs, liver, kidneys, oral mucosa, and brain


      • Usually not in bone marrow, lymph node, or spleen


Presentation



  • 1 or multiple skin lesions


  • Patches or plaques due to epidermal infiltrates



    • Tumors or nodules due to dermal infiltrates



      • ± ulcerated epidermis


  • Hemophagocytic syndrome (HPS) may be present in 45% of cases



    • More often in subcutaneous lesions



      • Related to release of cytotoxic molecules


Laboratory Tests



  • Cytopenias


  • ↑ liver function tests


Treatment



  • Adjuvant therapy



    • Multiagent chemotherapy ± radiotherapy



      • Poor response to allogenic stem cell transplant


Prognosis



  • Poor prognosis



    • 5-year survival: ˜ 11%


    • Subcutaneous disease is a poor prognostic indicator



      • Better prognosis if only disease in dermis or epidermis


    • HPS is a poor prognostic indicator



MICROSCOPIC PATHOLOGY


Histologic Features



  • 3 patterns of disease



    • Epidermotropic



      • Ranges from mild to marked


      • Can mimic mycosis fungoides or pagetoid reticulosis


    • Dermal



      • More dermal and epidermal involvement typically present than in subcutaneous panniculitis-like T-cell lymphoma


    • Subcutaneous



      • Lobules mostly involved


      • Septae less frequently involved and represents secondary spilling of T cells from lobules


      • Subcutis involvement can appear identical to subcutaneous panniculitis-like T-cell lymphoma of αβ cells, including rimming of fat cells


  • Often more than 1 pattern of disease in a patient



    • Different patterns of disease in a single biopsy or in different biopsies


  • Malignant T cells with nuclear atypia, hyperchromasia


  • Frequent necrosis/apoptosis and vascular invasion



    • Necrosis may be caused by released cytotoxic molecules


  • ↑ reactive histiocytes



    • Vacuolated foamy cytoplasm from imbibed material/lipid


    • With erythrophagocytosis or cytophagocytosis


Cytologic Features



  • Medium to large T cells with coarse, hyperchromatic-staining chromatin, sometimes vesicular nuclei, and variably prominent nucleoli


ANCILLARY TESTS


Immunohistochemistry

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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Cutaneous Gamma-Delta T-cell Lymphoma

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