BREAST PLASMACYTOMA: A CASE TREATED WITH IRRADIATION THAT EVOLVED TO FURTHER BILATERAL BREAST INVOLVEMENT AND SYSTEMIC DISEASE REFRACTORY TO CHEMOTHERAPY

Abstract

Introduction: Plasmacytomas are uncommon malignant lesions in the breast. Further knowledge is needed about the
presentation, diagnosis, and therapy of this disease. Case report: A 78-year-old woman had a previous diagnosis of sacral
bone plasmacytoma in March 2005 that was treated with radiotherapy. A new lesion involved in the cervical spine in
2008 was also irradiated. A mammogram and ultrasound found two well-defined nodules in January 2012 in the upper
outer quadrant of the right breast, with a total diameter of 38 mm. Biopsy showed a proliferation of cells with Ki-67 staining in more than 90% and positivity for CD38, CD138, CD45, and CD79A, an exclusive expression of lambda light chains.
The pathological diagnosis was anaplastic plasmacytoma. She received radiotherapy with remission of the breast lesions.
After further appearance of bone lesions, she started chemotherapy with bortezomib, melphalan, and prednisone in
January 2016. A PET study in July 2016 showed, among other findings, the presence of a 4-cm lesion in the upper-outer
quadrant of the left breast (SUVmax: 3.9). Biopsy gave a diagnosis of plasmacytoma, with cells staining strongly positive
for CD138, MUN1, and CD38, with the expression of lambda light chain. Chemotherapy was changed to lenalidomide plus
dexamethasone. A further PET in January 2017 displayed, among other findings, the persistence of the lesion in the left
breast (SUVmax: 5.4) with two new lesions in the right breast (SUVmax: 5.3 and 13). There was also a sacral progression,
and chemotherapy was changed to pomalidomide, dexamethasone plus cyclophosphamide. The evolution of the patient
was unfavorable, and she died in June 2017. Criteria for multiple myeloma were not present along the course of the disease. Conclusion: Evolution to bilateral involvement, relapse in the same breast, and refractoriness to chemotherapy are
remarkable aspects of this case report and give further information about this presentation of the disease.