CD30

CD30 is a transmembrane glycoprotein belonging to the tumor necrosis factor receptor (TNFR) superfamily, normally expressed at low levels on activated T and B lymphocytes. In pathology, CD30 is a key immunohistochemical marker: it is strongly and uniformly positive on Reed-Sternberg cells and their mononuclear Hodgkin cell variants in Classic Hodgkin Lymphoma (along with CD15, and typically CD45-negative, distinguishing it from non-Hodgkin lymphomas). CD30 is also the defining marker of Anaplastic Large Cell Lymphoma (ALCL), a T-cell non-Hodgkin lymphoma associated with ALK gene rearrangements (t(2;5)) in the ALK-positive subtype, which has a better prognosis than ALK-negative disease. Other CD30-positive entities include embryonal carcinoma (a germ cell tumor), lymphomatoid papulosis, and some cases of mycosis fungoides. Clinically, CD30 expression is therapeutically exploited by brentuximab vedotin, an antibody-drug conjugate linking an anti-CD30 monoclonal antibody to the microtubule-disrupting agent monomethyl auristatin E (MMAE), used in treatment of relapsed/refractory Hodgkin lymphoma and systemic ALCL. Recognizing CD30 positivity helps differentiate Hodgkin from non-Hodgkin lymphomas and guides targeted therapy selection.