Intravascular NK/T-Cell Lymphoma: What We Know about This Diagnostically Challenging, Aggressive Disease

Abstract

Intravascular lymphoma is a form of lymphoid malignancy characterized by neoplastic cells growing almost exclusively within the lumina of small- to medium-sized blood vessels. Most cases are of B-cell origin with rare cases of natural killer or T-cell lineage. Extranodal sites are affected, mainly the skin and central nervous system, although any organ may be involved. Intravascular NK/T-cell lymphoma deserves special attention because of its clinicopathologic features and the need for adequate immunophenotyping combined with clonality test for a proper diagnosis. Moreover, intravascular NK/T-cell lymphoma is strongly linked to Epstein-Barr virus (EBV), which is considered to play a role in tumorigenesis and to be responsible for the aggressive behavior of the disease. In this paper, we review the current knowledge on this rare lymphoma and, in particular, the most recent advances about its molecular landscape. The main distinguishing features with other EBV-related entities, such as extranodal NK/T-cell lymphoma, EBV-positive primary nodal T/NK-cell lymphoma, and aggressive NK-cell leukemia, are discussed to help pathologists obtain the correct diagnosis and consequently develop an adequate and prompt therapy response.

Keywords: EBV-positive primary nodal T/NK-cell lymphoma; Epstein–Barr virus; aggressive NK-cell leukemia; extranodal NK/T-cell lymphoma; intravascular NK/T-cell lymphoma.

Figure 1

High-power view showing kidney parenchyma with large, atypical cells growing within vascular spaces (see within red circle; hematoxylin and eosin, 200× magnification, previously unpublished, original image from S.A.).

Figure 2

High-power view showing central nervous system parenchyma with atypical cells within a vascular space (hematoxylin and eosin, 400× magnification, previously unpublished, original image from S.A.).

Figure 3

Medium-power view showing bone marrow with CD3-positive atypical cells within sinusoidal spaces (CD3 immunostaining, 100× magnification, previously unpublished, original image from S.A.).

Figure 4

High-power view showing lung parenchyma with perforin-positive atypical cells within vascular spaces (perforin immunostaining, 200× magnification, previously unpublished, original image from S.A.).

Figure 5

High-power view showing lung parenchyma with EBER-positive atypical cells within vascular spaces (in situ hybridization for EBV-encoded RNA, 400× magnification, previously unpublished, original image from S.A.).

Figure 6

High-power view showing a diffuse and polymorphic proliferation of atypical, medium- to large-sized lymphoid cells (hematoxylin and eosin, 200× magnification, previously unpublished, original image from S.A.).

Figure 7

High-power view showing a diffuse proliferation of CD56-positive atypical cells (CD56 immunostaining, 200× magnification, previously unpublished, original image from S.A.).

Figure 8

High-power view showing CD30-positive atypical cells (CD30 immunostaining, 400× magnification, previously unpublished, original image from S.A.).

Figure 9

Medium-power view showing a diffuse proliferation of EBER-positive cells (in situ hybridization for EBV-encoded RNA, 100× magnification, previously unpublished, original image from S.A.).