Anaplastic variant of diffuse large B‐cell lymphoma with hallmark cell appearance: Two cases highlighting a broad diversity in the diagnostics. Issue 4 (25th February 2018) - Sakakibara, Ayako
Abstract : The anaplastic variant of diffuse large B‐cell lymphoma (A‐DLBCL) is morphologically defined but remains an enigmatic disease in its clinicopathologic distinctiveness. Here, we report two cases involving Japanese women aged 59 years, both with A‐DLBCL with the hallmark cell appearance and both indistinguishable from common and giant cell‐rich patterns, respectively, of anaplastic lymphoma kinase (ALK)‐positive anaplastic large cell lymphoma. Case 1 was immunohistochemically positive for CD20, CD79a and OCT‐2 but not for the other pan–B‐cell markers, CD30 and ALK. Case 2 showed CD20 and CD30 positivity for 50% and 20% of tumor cells in addition to strong expression of p53 and MYC. Both were positive for fascin without Epstein–Barr virus association. Our cases provide additional support for the earlier reports that A‐DLBCL exhibits clinicopathologic features distinct from ordinal diffuse large B‐cell lymphoma (DLBCL), and documented its broader morphologic diversity than previously recognized. They also shed light on the unique feature of absent expression of pan–B‐cell markers except for CD20 and CD79a, suggesting that A‐DLBCL may biologically mimic a gray zone or intermediate lymphoma between DLBCL and classic Hodgkin lymphoma.