Baylor University Medical Center Proceedings April 2014, Volume 27, Number 2 | Page 52

Figure 2. CD20 immunostain indicating B-cell lymphoma (CD20 immunoperoxidase stain ×400).

The morphology, immunochemistry stains, and flow cytometry results supported a diagnosis of a lymphoma with features
intermediate between DLBCL and BL. Cytogenetic analysis was
performed with fluorescence in situ hybridization to reveal gene
rearrangements of BCL-2 (18q21), BCL-6 (3q27), and c-MYC
(8q24) genes (Figure 3). These features are consistent with a triplehit lymphoma. A bone marrow biopsy was negative. A positron
emission tomography scan revealed masses in the left inguinal
region, both kidneys, and the left lobe of the liver. The patient was
discharged to another facility in stable condition for treatment
and management options. On follow-up we were told that the
patient was treated with rituximab and hyper-CVAD (cyclophosphamide, vincristine, doxorubicin, dexamethasone) alternately
with rituximab, methotrexate, and cytarabine. Apparently the
patient had an initial response but the tumor recurred, and he
died about 6 months following the initial diagnosis.
DISCUSSION
B-cell lymphomas commonly have chromosomal gene rearrangements (1). For example, rearrangement of the BCL-2 or

a

c-MYC gene with the immunoglobulin gene (IG) can result in
follicular lymphoma or BL, respectively. However, to have two
gene rearrangements (double-hit lymphomas) is uncommon
(2). Translocation of the BCL-2 gene on chromosome 18q21
results in constant inactivation of apoptosis (3). Translocation
of the c-MYC gene on chromosome 8q24 results in constant cell
proliferation (3). These double-hit lymphomas are associated
with an aggressive clinical course, with poor response to treatment, complex karyotypes, and pathologic features of DLBCL
and BL (4). These pathological features include a “starry sky”
appearance with a high MiB-1 (which is consistent with BL),
but with larger cells with irregular nuclei and more prominent
nucleoli (which is consistent with DLBCL). The incidence is
estimated to be approximately 2% of all B-cell lymphomas (5).
The median survival time is reported to be about 5 months,
significantly shorter than for either DLBCL or BL (6).
Triple-hit lymphomas have been infrequently reported, with
only a small number of case reports noted. These lymphomas
are rare and the exact incidence is unknown. The Mitelman
lymphoma database in 2009 reported only eight triple-hit
lymphomas out of 796 lymphomas containing a BCL-6 gene
rearrangement (7). Triple-hit lymphomas are defined similar to
double-hit lymphomas as having morphologic, biologic, and
cytogenetic properties similar to both DLBCL and BL, but
possessing three, instead of two, gene rearrangements: c-MYC,
BCL-2, and BCL-6 genes (7). They are also associated with
a more aggressive clinical course, as these lymphomas have a
propensity to spread to extranodal sites, including the bone
marrow and central nervous system (8). Because of the more
complicated clinical course and gene rearrangements, the standard chemotherapy used for DLBLC or BL is ineffective (8).
The survival rate for these lymphomas has been reported to be
about 4 months, shorter than for DLBCL, BL, and doublehit lymphoma (8). One of the challenges is how to recognize
these lymphomas and order the appropriate molecular studies
so that aggressive treatment may be started. We are routinely
ordering molecular studies to detect BCL-2, BCL-6, and c-MYC
rearrangements on any B-cell lymphoma with features intermediate between DLBCL and BL, any lymphoma with a Ki-67
proliferation index >90%, and any DLBCL that has recurred
and is refractory to therapy.

b

c

Figure 3. Fluorescence in situ hybridization showing (a) BCL-2, (b) BCL-6, and (c) c-MYC gene rearrangements as a break-apart probe with
two separate signals (red and green). A normal cell, for comparison, has the red and green signals connected.
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Baylor University Medical Center Proceedings

Volume 27, Number 2