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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