Discussion:
Plasmacytoid PTLD is a rare entity in pediatric solid organ transplant
patients.2 The first case was described in a teenager
with a kidney transplant who presented with EBV-associated
post-transplant multiple myeloma.13 The largest case
series reported by Perry et al . included five cases in patients
after liver and small bowel combined transplant, and these patients
responded very well to high dose dexamethasone.7Several subsequent cases were treated successfully with bortezomib,
dexamethasone, with or without lenalidomide and autologous stem cell
transplant. Most patients remain in remission.8–10,12
Our patient initially responded well to bortezomib and dexamethasone but
relapsed with a different presentation of EBV-negative MZL. EBV-negative
MZL was recently reported by Galera et al as an unusual form of
PTLD.16 Here, the authors presented this as an
indolent disease process that could be managed conservatively. Our
patient was treated with bendamustine and rituximab as a targeted CD20
therapy, according to the BRISMA/IELSG36 study.18
He relapsed on therapy with plasma cell leukemia with a new t (14;16)
(q32;q23) anomaly. This translocation leads to the IgH/MAF fusion gene,
a high-risk cytogenetic abnormality occurring in 5% of myeloma
patients.19 Plasma cell leukemia is the most
aggressive form of plasma cell dyscrasias with very poor prognosis.
Treatment is based on myeloma-type regimens. Recently, novel agents have
advanced the treatment efficacy of multiple myeloma in adult
patients.17,20 The LYRA study showed a 44% partial
response rate after 4 cycles with 87% one year progression-free
survival.17 Although the peripheral leukemic cells
responded to this regimen, he passed away from gastrointestinal
hemorrhage secondary to progressive intraabdominal disease. We
hypothesize that his intraabdominal pathology may be distinct from his
plasma cell leukemia, as he rapidly progressed on a plasma cell targeted
regimen.
Our case highlights the heterogenicity of EBV-negative PTLD in pediatric
transplant patients, and the evolution of plasma cell neoplasms. The
rapid progress of three different forms of PTLD within less than one
year is a distinct feature. The literature of pediatric plasmacytoid
PTLD is isolated to a few case reports, thus, there is no standard of
care. Our case shows that patients with aggressive plasma cell PTLD may
respond to a combination of targeted and standard chemotherapy. Further
research is needed to understand the pathophysiology of these distinct
disease entities.