Primary Cutaneous CD4+ Small/Medium Pleomorphic T-cell Lymphoma



Primary Cutaneous CD4+ Small/Medium Pleomorphic T-cell Lymphoma


Aaron Auerbach, MD, PhD





Key Facts


Terminology



  • T-cell lymphoma of skin with small to medium-sized CD4(+) T cells and usually indolent clinical course



    • Provisional entity in 2008 WHO Classification of Tumors of Hematopoietic and Lymphoid Tissue


    • Lacks lesions typical of mycosis fungoides


Clinical Issues



  • Usually single plaque or tumor


  • Good prognosis, especially if single lesion


Microscopic Pathology



  • Dense dermal and subcutaneous infiltrate of small/medium-sized pleomorphic T cells


  • Sometimes focal epidermotropism


  • Scattered large T cells (< 30% of total)


  • Background reactive infiltrate


  • Granulomatous inflammation may be present


Ancillary Tests



  • CD3(+), CD4(+), CD8(−), CD30(−)


  • Loss of T-cell antigens


  • Positive follicular helper T-cell markers (PD1, CXCL13)


  • Clonal T-cell receptor gene rearrangements


  • Cytogenetics: No known abnormalities


  • Epstein-Barr virus small-encoded RNA(−)


Top Differential Diagnoses



  • Pseudolymphoma of the skin


  • Mycosis fungoides


  • Angioimmunoblastic T-cell lymphoma


  • Peripheral T-cell lymphoma unspecified


  • Cutaneous B-cell lymphoma







Low-power view of a primary cutaneous CD4(+) small/medium pleomorphic T-cell lymphoma shows a dense lymphoid infiltrate filling the dermis in a diffuse pattern of infiltration.






At higher power magnification, the lymphocytes are small to medium in size and show moderate atypia and pleomorphism image.


TERMINOLOGY


Abbreviations



  • Primary cutaneous CD4(+) small/medium pleomorphic T-cell lymphoma (SMPTCL)


Synonyms



  • Idiopathic T-cell lymphomatoid hyperplasia


Definitions



  • T-cell lymphoma of skin with small to medium-sized CD4(+) T cells, and usually indolent clinical course



    • Without typical patches/plaques of mycosis fungoides


  • Provisional entity in 2008 WHO Classification of Tumors of Hematopoietic and Lymphoid Tissue



    • Nonaggressive natural history, but worrisome histologic and molecular features


ETIOLOGY/PATHOGENESIS


Idiopathic



  • Cause of this lymphoma unknown Postulated Normal Cell Counterpart


  • CD4(+) helper T cell


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare



      • 2% of cutaneous T-cell lymphomas in the Dutch and Austrian Cutaneous Lymphoma Group Registry


  • Age



    • Median: 53 years; range: 3-90 years


  • Gender



    • M:F = 0.5:1


Site



  • Head and neck area most common



    • Upper torso often


    • Lower extremities rare


Presentation



  • Single plaque or tumor



    • Less commonly > 1 tumor nodule


    • Less commonly ≥ 1 papules


    • No lesions (patches/plaques) typical of mycosis fungoides


  • Usually asymptomatic other than skin lesions



    • No lymphadenopathy


    • No systemic disease


Laboratory Tests



  • No known laboratory abnormalities


Natural History



  • Does not usually disseminate



    • Rarely, local recurrence is seen


Treatment



  • Excision


  • Radiation therapy


  • Usually nonaggressive therapy



    • Especially if single lesion


Prognosis



  • Mostly favorable outcome, especially if solitary lesion or localized to skin



    • Better prognosis than secondary cutaneous T-cell lymphomas


    • Better prognosis than primary cutaneous peripheral T-cell lymphoma, not otherwise specified


  • Nonaggressive disease



    • Overall 5-year survival: 60-80%


    • Disease-specific 5-year survival up to 75%


  • Good prognostic indicators



    • Solitary lesion


    • Disease localized to skin



  • Worse prognostic indicators



    • Multiple lesions


    • Large lesions


MACROSCOPIC FEATURES


General Features



  • Usually single, less often multiple firm lesion(s)


MICROSCOPIC PATHOLOGY


Histologic Features



  • Dense dermal infiltrate



    • Sometimes involves subcutaneous tissue


    • Usually nonepidermotropic



      • Rarely focal epidermotropism


  • Growth pattern



    • Diffuse


    • Nodular


  • Size of T cells



    • Small or medium in most cases


    • Large cells can also be seen



      • When present, < 30% of total cells


  • Pleomorphic with some nuclear irregularity


  • Other features



    • Background reactive infiltrate is fairly common



      • Small reactive lymphocytes, eosinophils, and histiocytes


    • ↑ reactive-appearing B cells also often present


    • Granulomatous inflammation can be seen


Cytologic Features



  • Rarely diagnosed by cytology


ANCILLARY TESTS


Immunohistochemistry



  • T-cell antigens positive



    • CD2(+), CD3(+), CD5(+), CD7(+)


    • Rarely loss of 1 or more T-cell antigens



      • CD7 > CD5, CD2


    • CD4(+), CD8(−)


  • Expresses follicular helper T-cell markers



    • PD1(+), CXCL13(+), Bcl-6(+)


  • Cytotoxic markers negative



    • TIA, GZM-B, and perforin


  • CD30(−), LMP1(−)


Cytogenetics



  • No known specific abnormalities


In Situ Hybridization



  • Epstein-Barr virus small-encoded RNA (EBER) negative


PCR



  • TCR gene rearrangement clonal



    • 60% in one series


  • IgH immunoglobulin gene rearrangements polyclonal


DIFFERENTIAL DIAGNOSIS


Atypical Reactive Lymphoid Infiltrates (“Pseudolymphomas”) of the Skin

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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Primary Cutaneous CD4+ Small/Medium Pleomorphic T-cell Lymphoma

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