Abstract

The metastases of breast cancer to bone marrow can mimic plasma cell neoplasia morphologically due to presence of plasma cell-like neoplastic cells and even positive staining for a carcinoma metastasis with plasma cell marker CD138/ Syndecan-1 may cause confusion in diagnosis. This case report details a 71-year-old female initially suspected of plasma cell myeloma due to hypercalcemia and multiple lytic bone lesions. However, a bone marrow biopsy revealed syndecan-1 positive metastatic lobular breast cancer mimicking a plasma cell neoplasm. Bone marrow aspirate smears and the bone marrow biopsy showed plasmacytoid cells that were strongly positive for syndecan-1, indicating metastatic lobular breast carcinoma. The overexpression of syndecan-1 was a critical marker in identifying the breast cancer cells, emphasizing the diagnostic challenges when syndecan-1 positive metastatic lobular BC presents with plasmacytoid features.

Keywords: bone marrow, lobular breast carcinoma, metastatic breast cancer, plasmacytoid neoplasms, syndecan-1

License

Copyright (c) 2026 The Author(s). This is an open access article distributed under the Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is properly cited.

How to Cite

1.
Yaprak Bayrak B, Tunce EB, İşgören S, Cantürk NZ. Metastatic lobular breast carcinoma positive for syndecan-1 mimicking a plasma cell neoplasm: a case report. J Trends Med Invest. 2026;2(1):44-51. https://doi.org/10.64512/JTMI.2026.18

References

  1. Cerbelli B, Pisano A, Pignataro MG, et al. Overexpression in metastatic breast cancer supports Syndecan-1 as a marker of invasiveness and poor prognosis. Clin Exp Med. 2023;23(5):1641-1647. https://doi.org/10.1007/s10238-022-00880-7
  2. Wang H, Zhang Y, Yang Z, et al. Clinical/prognostic significance of Syndecan-1 expression in invasive breast carcinoma with distant metastasis and its correlation with tumor immunity. Pathol Res Pract. 2023;250:154787. https://doi.org/10.1016/j.prp.2023.154787
  3. Akagi H, Shimada A, Chin K, Domoto H. Successful stabilization of symptomatic bone marrow metastasis two times in a breast cancer patient. Anticancer Res. 2021;41(6):3139-3144. https://doi.org/10.21873/anticanres.15099
  4. Kind S, Jaretzke A, Büscheck F, et al. A shift from membranous and stromal syndecan-1 (CD138) expression to cytoplasmic CD138 expression is associated with poor prognosis in breast cancer. Mol Carcinog. 2019;58(12):2306-2315. https://doi.org/10.1002/mc.23119
  5. Chute C, Yang X, Meyer K, et al. Syndecan-1 induction in lung microenvironment supports the establishment of breast tumor metastases. Breast Cancer Res. 2018;20(1):66. https://doi.org/10.1186/s13058-018-0995-x
  6. Canevari M, Wells J, Pryor E. Metastatic CD138+ lobular breast carcinoma mimicking a plasma cell neoplasm. Am J Clin Pathol. 2019;152(Suppl 1):S107. https://doi.org/10.1093/ajcp/aqz121.007
  7. Nguyen TL, Grizzle WE, Zhang K, Hameed O, Siegal GP, Wei S. Syndecan-1 overexpression is associated with nonluminal subtypes and poor prognosis in advanced breast cancer. Am J Clin Pathol. 2013;140(4):468-74. https://doi.org/10.1309/AJCPZ1D8CALHDXCJ
  8. Miše I, Vučić M. Comparison of Syndecan-1 immunohistochemical expression in lobular and ductal breast carcinoma with nodal metastases. Anal Cell Pathol (Amst). 2018;2018:9432375. https://doi.org/10.1155/2018/9432375
  9. Kotchetkov R, Ellison E. Metastatic lobular breast carcinoma mimicking multiple myeloma. Blood. 2014;124(14):2313. https://doi.org/10.1182/blood-2014-07-584235