GZL diagnostic algorithm. The minimum diagnostic panel for workup of GZL should include B-cell markers (CD20 and PAX5), MUM1, CD30, and CD15. A broad panel of T-cell and cytotoxic markers is desirable to rule out anaplastic large cell lymphoma. EBV by in situ hybridization should also be a part of the diagnostic panel. (Top) Stepwise approach to the diagnostic evaluation of GZL. (Lower balloon) depicts potential pitfalls in the diagnostic evaluation of GZL to also consider. FNA, fine needle aspiration.