Usually the architecture of lymph nodes is partially effaced in ALK+ ALCL; the tumor cells commonly infiltrate the subcapsular sinuses and paracortical region, often showing a striking intrasinusoidal dissemination in a sheet-like pattern, mimicking a metastatic carcinoma (Figure 1A) [15,27,28,29]. The gene discussed is ALK; the disease is anaplastic large cell lymphoma.