To the Editor,
22q11.2 deletion syndrome (22q11.2DS) is a rare congenital disorder
resulting in a variety of immunological changes, one of which is
secondary immune cytopenias that tend to be recurrent and difficult to
manage1,2. There is currently no standard regimen for
treating immune cytopenias in 22q11.2DS3. We present
two cases of Evans syndrome (ES) in the setting of 22q11.2DS with an
absence of typical phenotypic features.
The first case is of a previously healthy 18-year-old male who presented
at age 16 with mucocutaneous bleeding and thrombocytopenia with a
positive Coombs test but without active hemolysis. His evaluation
included CT chest, abdomen, and pelvis which showed axillary and
inguinal adenopathy. A biopsy of an enlarged lymph node was performed,
revealing reactive lymphoid hyperplasia. Bone marrow evaluation was
negative for increased blasts with normal trilineage hematopoiesis. He
was clinically diagnosed with immune thrombocytopenic purpura (ITP) but
did not respond to two doses of intravenous immunoglobulin (IVIG) and
his response to systemic steroids was suboptimal. Subsequently, he was
initiated on romiplostim, a thrombopoietin receptor agonist (TPO-RA),
with an improvement in platelet counts. Following discontinuation of
romiplostim, he remained thrombocytopenic with baseline platelet counts
between 80,000-100,000/µL (Figure 1). Other than occasional nosebleeds,
he was otherwise asymptomatic. One year later, he presented with
jaundice and was found to have warm autoimmune hemolytic anemia (AIHA).
His anemia was responsive to systemic steroids. Due to persistent
lymphopenia and evolving hypogammaglobinemia, a genetic panel for
immunodeficiency was initiated and revealed a gross deletion inTBX1 . Further, the SNP microarray confirmed 22q11.2DS.
The second case is of an 8-year-old male with a history of partial cleft
palate who was initially diagnosed with ES when he was one year old. His
anemia resolved with a steroid course although he remained
thrombocytopenic. He subsequently had two additional episodes of warm
AIHA treated with rituximab courses due to insufficient response to
steroids. He also developed steroid-induced hyperglycemia requiring
insulin therapy. Due to persistent cytopenias, he underwent bone marrow
evaluation to rule out the infiltrative marrow process. Incidentally,
SNP microarray from his bone marrow aspirate identified 22q11.2DS.
Following a diagnosis of 22q11.2DS, he had recurrent episodes of immune
cytopenias either manifesting as acute warm AIHA or acute worsening of
his thrombocytopenia. He typically required both steroid and rituximab
during relapse of his warm AIHA. He eventually was started on
romiplostim with normalization of his platelet counts. He maintained
normal platelet counts following the discontinuation of romiplostim
(Figure 1). In-depth immunophenotyping performed on both patients
revealed mild hypogammaglobulinemia, moderate T cell lymphopenia,
significantly reduced CD4+ naïve T cells, and decreased class-switched
memory B cells. Table 1 below summarizes the immunologic findings in
these two patients.
Multiple cases of ES have been documented in DiGeorge syndrome (DGS)
individuals after the first reported case in 1990 involving an infant
who developed ITP and subsequently AIHA during
childhood4, suggesting that a thorough investigation
for 22q11DS is warranted in individuals presenting with recurrent immune
cytopenia, even without typical DGS features4,5. The
first case described in this paper did not have the typical features of
DGS, which subsequently led to a delay in the diagnosis until 18 years
upon further investigation of recurrent autoimmune cytopenia. There were
many theories explaining the increased risk of autoimmunity in patients
with DGS. Deshpande et al. study on 467 patients with pDGS showed
patients with autoimmunity had lower levels of CD3+, CD3+CD4+, and naïve
CD4+CD45RA+CD27+ T lymphocytes compared with pDGS patients without
autoimmunity6. It was concluded that premature CD4+
T-cell aging, and lymphopenia-induced spontaneous peripheral T-cell
proliferation might contribute to the pathogenesis of autoimmunity in
patients with pDGS7. A case-control study showed
patients with hemolytic anemia (HA) tend to have lower naïve CD4+ cells,
higher memory CD4+ T cells, lower recent thymic emigrants, lower
class-switched B cells and higher naïve B cells compared to the non-HA
group1.
Autoimmune cytopenia (AIC) in DGS seems to be resistant to treatment. In
a study on treatment selection and response for patients with pDGS with
AIC, 4 out of 7 pDGS patients with ES had refractory cytopenias
requiring second-line immunomodulation including rituximab and
sirolimus8. Among those four patients, there was a
background of antibody deficiency and lower naïve T cell counts compared
to pDGS patients with mild AIC8. We observed similar
immunophenotypes in our two patients and recommend extensive B and T
cell immunophenotyping at diagnosis and close monitoring of these
biomarkers for early identification of patients at risk for severe and
recurrent AIC. Although our patients demonstrated good response to
TPO-RA, it may not fully address the underlying immune mechanism driving
the peripheral destructions due to autoreactive T and B cells. Long term
T-cell directed immunomodulation maybe the preferred therapy for certain
patients with recurrent AIC.
We conclude that there is an increased risk of having AIC among patients
with 22q11.2DS. This is suggested by specific immunophenotypes according
to the literature. Managing cases of AIC secondary to 22q11.2DS remains
controversial. There is no standard regimen to treat those patients. We
suggest those patients be treated differently, as their disease course
is much more complicated. Our two patients diagnosed with 22q11.2DS with
ES responded well to the TPO-RA after trying multiple regimens.
Table 1. Pertinent immunophenotyping results