BCR and post-transplant lymphoproliferative disease: These are for example classical Hodgkin lymphoma, whose malignant Reed-Sternberg und Hodgkin cells have lost their B-cell-phenotype including functional BCR genes (187), PTLD with crippled BCR genes (210), or primary mediastinal B cell lymphoma (211, 212), which usually does not express sIg either (Figure 4).