GIANT RETROPERITONEAL PLASMACYTOID NEOPLASM WITH IMMUNOMORPHOLOGIC OVERLAP BETWEEN EXTRAMEDULLARY PLASMACYTOMA AND PLASMABLASTIC LYMPHOMA: A DIAGNOSTIC AND THERAPEUTIC CHALLENGE
- 1Hospital Santa Izabel/Oncoclínicas, Santa Casa da Bahia, Salvador, BA, Brazil
Abstract
Background: Isolated extramedullary plasmacytoma (EMP) is a rare plasma cell neoplasm, accounting for 3–5% of plasma cell malignancies, with strong predilection for the head and neck region. Retroperitoneal presentation is exceptional, and histopathological distinction from plasmablastic lymphoma (PBL) — an aggressive differential requiring a markedly different treatment approach — remains a recognized diagnostic challenge in hematopathology. Case report: A 43-year-old man presented with a one-year history of progressive limb edema and abdominal distension. Diagnostic biopsy was delayed seven months by public health system wait times, during which the tumor progressed to a giant retroperitoneal mass (15.6 × 18.1 × 21.7 cm), causing bilateral hydroureteronephrosis with KDIGO stage 3 post-renal acute kidney injury requiring first-time hemodialysis, bilateral ureteral stenting/nephrostomy, deep vein thrombosis requiring inferior vena cava filter placement (pulmonary embolism was ruled out), and a postoperative enterocutaneous fistula complicated by a frozen abdomen. Initial biopsy showed monoclonal, lambda-restricted plasma cell proliferation; an expanded immunohistochemical panel later revealed a Ki-67 index of ∼95% and c-Myc positivity in 60% of cells, alongside absence of B-lineage markers and HHV-8 — findings favoring EMP but insufficient to definitively exclude PBL, as EBER-ISH and MYC FISH could not be performed due to resource constraints. Bone marrow flow cytometry showed no clonal plasma cell population, and whole-body CT showed no lytic lesions. The frozen abdomen precluded both fistula repair and radiotherapy. In accordance with the patient's wishes, intensive chemotherapy was declined; he received biweekly bortezomib-dexamethasone but died from progressive surgical-obstructive complications. Conclusion: This case illustrates a rare, giant retroperitoneal presentation of EMP in which cascading mechanical complications — compounded by diagnostic delay within a resource-constrained health system — foreclosed definitive local therapy despite active systemic treatment. It further documents, through a complete immunohistochemical workup, the recognized diagnostic gray zone between EMP and PBL, highlighting real-world limitations in achieving diagnostic certainty when confirmatory molecular testing is unavailable.
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BibTeX
@article{junior2026giant,
title = {{GIANT RETROPERITONEAL PLASMACYTOID NEOPLASM WITH IMMUNOMORPHOLOGIC OVERLAP BETWEEN EXTRAMEDULLARY PLASMACYTOMA AND PLASMABLASTIC LYMPHOMA: A DIAGNOSTIC AND THERAPEUTIC CHALLENGE}},
author = {Valney Oliveira SANTOS JUNIOR and Maura Alice Santos ROMEO and Beatriz Moura PORTUGAL and Lorhane Nunes DOS ANJOS and Giulia Beatriz Correia MATOS},
journal = {Hematology, Transfusion and Cell Therapy},
year = {2026},
month = oct,
doi = {10.1016/j.htct.2026.107874},
url = {https://doi.org/10.1016/j.htct.2026.107874},
note = {CC BY},
}
RIS
TY - JOUR
TI - GIANT RETROPERITONEAL PLASMACYTOID NEOPLASM WITH IMMUNOMORPHOLOGIC OVERLAP BETWEEN EXTRAMEDULLARY PLASMACYTOMA AND PLASMABLASTIC LYMPHOMA: A DIAGNOSTIC AND THERAPEUTIC CHALLENGE
AU - Valney Oliveira SANTOS JUNIOR
AU - Maura Alice Santos ROMEO
AU - Beatriz Moura PORTUGAL
AU - Lorhane Nunes DOS ANJOS
AU - Giulia Beatriz Correia MATOS
PY - 2026
DA - 2026/10/23
JO - Hematology, Transfusion and Cell Therapy
DO - 10.1016/j.htct.2026.107874
UR - https://doi.org/10.1016/j.htct.2026.107874
AB - Background: Isolated extramedullary plasmacytoma (EMP) is a rare plasma cell neoplasm, accounting for 3–5% of plasma cell malignancies, with strong predilection for the head and neck region. Retroperitoneal presentation is exceptional, and histopathological distinction from plasmablastic lymphoma (PBL) — an aggressive differential requiring a markedly different treatment approach — remains a recognized diagnostic challenge in hematopathology. Case report: A 43-year-old man presented with a one-year history of progressive limb edema and abdominal distension. Diagnostic biopsy was delayed seven months by public health system wait times, during which the tumor progressed to a giant retroperitoneal mass (15.6 × 18.1 × 21.7 cm), causing bilateral hydroureteronephrosis with KDIGO stage 3 post-renal acute kidney injury requiring first-time hemodialysis, bilateral ureteral stenting/nephrostomy, deep vein thrombosis requiring inferior vena cava filter placement (pulmonary embolism was ruled out), and a postoperative enterocutaneous fistula complicated by a frozen abdomen. Initial biopsy showed monoclonal, lambda-restricted plasma cell proliferation; an expanded immunohistochemical panel later revealed a Ki-67 index of ∼95% and c-Myc positivity in 60% of cells, alongside absence of B-lineage markers and HHV-8 — findings favoring EMP but insufficient to definitively exclude PBL, as EBER-ISH and MYC FISH could not be performed due to resource constraints. Bone marrow flow cytometry showed no clonal plasma cell population, and whole-body CT showed no lytic lesions. The frozen abdomen precluded both fistula repair and radiotherapy. In accordance with the patient's wishes, intensive chemotherapy was declined; he received biweekly bortezomib-dexamethasone but died from progressive surgical-obstructive complications. Conclusion: This case illustrates a rare, giant retroperitoneal presentation of EMP in which cascading mechanical complications — compounded by diagnostic delay within a resource-constrained health system — foreclosed definitive local therapy despite active systemic treatment. It further documents, through a complete immunohistochemical workup, the recognized diagnostic gray zone between EMP and PBL, highlighting real-world limitations in achieving diagnostic certainty when confirmatory molecular testing is unavailable.
SN - 2531-1379
SN - 2531-1387
ER -