Table 1

Interpretation of immunohistochemistry

TdTCD3CD4CD8GB/PTIA1CD56EBVCD30ALKCharacteristic feature(s)
*The T cell origin of this entity is disputed; †these tumours are usually CD57+.
ALCL, anaplastic large cell lymphoma; EBV, Epstein-Barr virus; GB, granzyme B; HTLV1, human T cell lymphotropic virus 1; NK, natural killer; NOS, not otherwise specified; P, perforin; PLL, prolymphocytic leukaemia; TdT, terminal deoxynucleotidyl transferase; +, positive; −, negative; +/−, usually positive, sometimes negative; −/+, usually negative, sometimes positive.
Predominantly leukaemic
    Precursor T lymphoblastic leukaemia+++/−+/−Frequent presentation with mediastinal mass
    T cell PLL++/−−/+Multi-organ involvement including the skin
    T cell large granular lymphocytic leukaemia+−/++/−+++/−*Indolent behaviour
    Aggressive NK cell leukaemia+++++Multi-organ involvement, highly aggressive
    Adult T cell lymphoma/leukaemia (HTLV1+)+++/−Usually widely disseminated, very rare in non-endemic areas
Predominantly extranodal
    Extranodal NK/T cell lymphoma, nasal type+++++−/+Nearly always primary nasal localisation
    Enteropathy-type T cell lymphoma+−/+++−/+−/+−/+Usually, but not always associated with coeliac disease
    Hepatosplenic γλ T cell lymphoma+++Involvement of liver, spleen, and bone marrow
Predominantly cutaneous
    Blastic NK cell lymphoma†−/++−/+−/++Difficult distinction from T cell acute lymphoblastic leukaemia and myeloblastic leukaemia
    Subcutaneous panniculitis-like T cell++++−/+Rimming of adipocytes
    Mycosis fungoides/Sezary syndrome+−/+−/+−/+Epidermotropism and Pautrier abscess formation
    ALCL primary cutaneous−/++/−−/++/−+/−+Distinction with lymphomatoid papulosis only on basis of clinical behaviour
Predominantly nodal
    ALCL systemic−/++/−−/++/−+/−++/−ALK positive cases demonstrate favourable clinical outcome
    Peripheral T cell lymphoma, NOS++/−−/++/−Usually generalised disease
    Angio immunoblastic T cell lymphoma++++Aggregates of CD21 positive dendritic cells, outside follicle centres. EBV positive B cells