Solitary Bone Plasmacytoma of the Scapula: A Rare Localization With Remarkable Radiotherapy Outcome

Sep 29, 2026

Solitary bone plasmacytoma (SBP) is a rare plasma cell neoplasm defined by localized monoclonal plasma cell proliferation in bone without systemic involvement, distinguishing it from multiple myeloma. Although the axial skeleton is most commonly affected, shoulder girdle involvement is exceptionally uncommon. This case reports a 48-year-old woman with progressive left shoulder pain and an enlarging scapular mass. Imaging showed a large osteolytic lesion with soft-tissue extension; histopathology and immunohistochemistry confirmed solitary plasmacytoma. Comprehensive staging excluded systemic disease, and definitive radiotherapy achieved marked lesion regression after treatment.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages15

Reading Time38 min

AccessFree to download

Case Report Overview

Presentation and Symptoms

Diagnostic Work-up and Exclusion of Systemic Disease

Radiotherapy Treatment and Response

Clinical Significance and Follow-up Considerations

Review began 11/18/2025 Review ended 11/26/2025 Published 12/05/2025 © Copyright 2025 El Mjabber et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CCBY 4.0. , which permits unrestricted use , distribution , and reproduction in any medium , provided the original author and source are credited. DOI: 10.7759/cureus.98499 Open Access Case Report Solitary Bone Plasmacytoma of the Scapula: A Rare Localization With Remarkable Radiotherapy Outcome Reyzane El Mjabber 1, 2 , Rim Alami 3, 2 , Ech-Cherki El Mjabber 4 , Zineb Dahbi 3, 2 , Fadila Kouhen 3, 2, Nabil Ismaili 5, 6 , Sanaa El Majjaoui 3, 2 , Asmaa Naim 3, 2 1. Radiation Oncology, Mohammed VI University of Sciences and Health (UM6SS), Casablanca, MAR 2. Radiation Oncology, International University Cheikh Khalifa Hospital, Casablanca, MAR 3. Radiation Oncology, Mohammed VI University of Sciences and Health (UM6SS), Casablanca, MAR 4. Orthopaedics and Trauma, Clinique AL Marjane, Khouribga, MAR 5. Medical Oncology, Mohammed VI University of Sciences and Health (UM6SS), Casablanca, MAR 6. Medical Oncology, International University Cheikh Khalifa Hospital, Casablanca, MAR Corresponding author: Reyzane El Mjabber, [reyzaneelmjabber@gmail.com](reyzaneelmjabber@gmail.com) Abstract Solitary bone plasmacytoma (SBP) is a rare plasma cell neoplasm characterized by localized proliferation of monoclonal plasma cells in bone without systemic involvement, which distinguishes it from multiple myeloma. Although the axial skeleton is most frequently affected, involvement of the shoulder girdle is exceptionally uncommon. We present the case of a 48-year-old woman who experienced progressive left shoulder pain and noted an enlarging mass over six months. Imaging revealed a large osteolytic lesion in the scapula with extension into surrounding soft tissue. Histopathology and immunohistochemistry confirmed the diagnosis of solitary plasmacytoma. Comprehensive staging, including bone marrow biopsy and 18F-FDG PET/CT (Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography), excluded systemic disease. The patient underwent definitive radiotherapy, receiving 50 Gy (Grays) in 25 fractions via a 3D (threedimensional) conformal technique with careful target delineation. Treatment was well tolerated, with only grade I radiodermatitis reported. Follow-up imaging two months after therapy demonstrated significant lesion regression, partial re-ossification, and reduction of soft-tissue involvement. SBP of the scapula represents a rare clinical entity, and radiotherapy continues to be the treatment of choice, offering excellent local control. Despite favorable local outcomes, long-term monitoring is crucial due to the potential risk of progression to multiple myeloma. Documenting rare localizations contributes toa better understanding of disease behavior and supports tailored management approaches. Categories: Radiation Oncology, Oncology, Orthopedics Keywords: local control, monoclonal plasma cells, radiotherapy, rare localization, solitary bone plasmacytoma Introduction The solitary plasmacytoma (SP) is a rare malignant tumor characterized by a clonal proliferation of monoclonal plasma cells, without associated systemic involvement, unlike multiple myeloma. It accounts for less than 5% of plasma cell neoplasms and is distinguished by its unique localization, either in bone (solitary bone plasmacytoma [SBP]) or in soft tissues (extramedullary plasmacytoma [EMP]) . Clinically, SBP presents symptoms related to the local tumor mass: pain, swelling, and pathological fractures. The absence of systemic signs such as anemia, hypercalcemia, or renal failure distinguishes SP from multiple myeloma and can sometimes make the diagnosis challenging. The diagnosis is based on histology, confirming the monoclonal plasma cell proliferation, and on a comprehensive work-up aimed at excluding systemic involv

FAQs

What is solitary bone plasmacytoma (SBP) and how does it differ from multiple myeloma?

SBP is a rare plasma cell neoplasm with localized monoclonal plasma cells in bone without systemic involvement. This lack of systemic disease distinguishes SBP from multiple myeloma.

How was systemic involvement excluded in this case?

Comprehensive staging included bone marrow biopsy and 18F-FDG PET/CT to exclude systemic disease.

What radiotherapy regimen was used and what was the outcome?

The patient received definitive radiotherapy of 50 Gy in 25 fractions using a 3D conformal technique. Follow-up imaging two months later showed significant lesion regression, partial re-ossification, and reduced soft-tissue involvement.

Sep 29, 2026

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