{
  "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.",
  "abstract_shown": true,
  "affiliations": [
    "Hospital Santa Izabel/Oncoclínicas, Santa Casa da Bahia, Salvador, BA, Brazil"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Valney Oliveira SANTOS JUNIOR"
    },
    {
      "affs": [
        0
      ],
      "name": "Maura Alice Santos ROMEO"
    },
    {
      "affs": [
        0
      ],
      "name": "Beatriz Moura PORTUGAL"
    },
    {
      "affs": [
        0
      ],
      "name": "Lorhane Nunes DOS ANJOS"
    },
    {
      "affs": [
        0
      ],
      "name": "Giulia Beatriz Correia MATOS"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ewqtqqjgd08vw.bib",
  "cited_by": 0,
  "doi": "10.1016/j.htct.2026.107874",
  "fulltext_url": "http://www.sciencedirect.com/science/article/pii/S2531137926016214",
  "id": "ewqtqqjgd08vw",
  "issns": [
    "2531-1379",
    "2531-1387"
  ],
  "landing_url": "https://doi.org/10.1016/j.htct.2026.107874",
  "language": "en",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "lcc",
      "RC633-647.5"
    ],
    [
      "openalex",
      "2720|Multiple Myeloma Research and Treatments"
    ]
  ],
  "openalex": "W7223087848",
  "pdf_url": "https://www.sciencedirect.com/science/article/pii/S2531137926016214/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": "Elsevier",
  "ris": "https://research.draconitic.com/paper/ewqtqqjgd08vw.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T13:43:21Z",
      "native_id": "ecea1cecd15e4cb58c71c800a48f29d7",
      "source": "doaj",
      "url": "https://doi.org/10.1016/j.htct.2026.107874"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "lcc:RC633-647.5",
      "subfield": "endocrinology-metabolism"
    }
  ],
  "title": "GIANT RETROPERITONEAL PLASMACYTOID NEOPLASM WITH IMMUNOMORPHOLOGIC OVERLAP BETWEEN EXTRAMEDULLARY PLASMACYTOMA AND PLASMABLASTIC LYMPHOMA: A DIAGNOSTIC AND THERAPEUTIC CHALLENGE",
  "title_text": "GIANT RETROPERITONEAL PLASMACYTOID NEOPLASM WITH IMMUNOMORPHOLOGIC OVERLAP BETWEEN EXTRAMEDULLARY PLASMACYTOMA AND PLASMABLASTIC LYMPHOMA: A DIAGNOSTIC AND THERAPEUTIC CHALLENGE",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T13:43:21Z",
  "url": "https://research.draconitic.com/paper/ewqtqqjgd08vw",
  "venue": "Hematology, Transfusion and Cell Therapy",
  "versions": []
}