ALK-positive anaplastic large cell lymphoma in adults

Abstract

ALK-positive anaplastic large cell lymphoma (ALCL) represents approximately 6-7% of the mature T-cell lymphomas. This subtype contains a translocation between the ALK gene on chromosome 2 and one of several other genes that together form an oncogene. The most frequent translocation is t(2;5) which combines ALK with NPM1. This lymphoma has a median age of 34 years, is more common in males, and is in advanced stage at the time of diagnosis in most patients. ALK-positive ALCL is the most curable of the peripheral T-cell lymphomas. The CHOP regimen has been most frequently used, but results are improved with the substitution of brentuximab vedotin for vincristine (BV-CHP) and the addition of etoposide (CHOEP), with BV-CHP being favored. Salvage therapies include allogeneic or autologous bone marrow transplantation, BV, if not used as part of the primary therapy, and ALK inhibitors. The latter are very active and likely to be incorporated into the primary therapy.

Keywords: ALCL; ALK positive ALCL; Lymphoma; PTCL.

Figure 1.. Morphology and Immunohistochemistry of ALCL.

A) By H&E (100x), the common pattern of ALCL shows pleomorphic cells. B) At higher power (400x), there are hallmark cells with reniform nuclei and variably eosinophilic, perinuclear cytoplasm. C) H&E (400x) The small cell variant of ALCL has a predominance of small cells with irregular nuclei and fewer hallmark cells. D–G) The immunostains correspond to the common pattern in panel A. The CD3 (D, 100x) is negative in the neoplastic cells, while ALK (E, 100x), CD30 (F, 100x), and granzyme B (G, 100x) are positive.