Case Report

Volume 16, Number 9, September 2025, pages 360-365

Radiotherapy for Isolated Breast Myeloid Sarcoma

Myeloid sarcoma (MS), also referred to as granulocytic sarcoma (GS) or chloroma, is an extramedullary tumor that proliferates and invades the tissues in which it is found. The tumor is composed of malignant immature white blood cells of myeloid lineage. It often occurs with acute myeloid leukemia (AML) or can present at the time of AML relapse. However, it can be diagnosed independent of bone marrow infiltration or circulating leukemia cells [1-5]. Patients’ clinical presentation varies largely depending on the location of the mass. Although it can be in almost any tissue, it is frequently found in the soft tissues, peritoneum, bone, skin and lymph nodes [1, 2, 3, 5] Due to the rarity of MS presentation in the breast, it is often misdiagnosed and requires a high index of suspicion when identifying the lesion. Early recognition may save the patient from unnecessary procedures and allows for the appropriate treatment to be initiated [2, 6, 7]. Due to the lack of treatment consensus guidelines, the approach to MS in the breast may pose challenges. However, systemic and local therapy (radiotherapy (RT) and surgery) are indicated in many cases [1-5].

Here, we report a case of MS localized to the breast without evidence of circulating leukemia cell or bone marrow infiltration, responding favorably to salvage local RT after initially being treated with standard AML treatment including multi-agent chemotherapy and allogeneic stem cell transplant.

A previously well 33-year-old female, with no relevant past medical history, presented in October 2013 with a lump in her right breast. The lesion was biopsied, and the morphology and immunochemistry performed revealed an MS, most often associated with a form of AML. However, further investigations such as peripheral blood count, blood and bone marrow morphology were normal, indicating no evidence of AML. Subsequently, the patient underwent two cycles of chemotherapy which she tolerated well; the first, “7 + 3”, consisted of cytarabine (araC) and daunomycin, and two cycles of high-dose cytarabine (HDAC). The breast mass quickly resolved after the first cycle of chemotherapy. After initial induction chemotherapy, the patient was reviewed by several hematologists at two separate tertiary care hospitals. The patient, despite being in clinical remission, was keen for aggressive upfront management because of the fear of relapse and requested further treatment similar to the management of AML. Therefore, in May 2014, the patient underwent a matched unrelated donor (MUD) allogeneic stem cell transplant following a traditional myeloablative busulfan, cyclophosphamide, and anti-thymocyte globulin (BuCyATG) conditioning regimen. Graft-vs-host disease (GVHD) prophylaxis consisted of traditional tacrolimus and a short course of methotrexate. The transplant was well tolerated, and no major complications were encountered. She did not develop GVHD requiring systemic immunosuppressive therapy and was quickly tapered off tacrolimus.

In September 2014, she noticed another lump in her right breast, and ultrasound imaging confirmed a mass measuring 1.6 × 1.1 cm mass. Repeat biopsy confirmed recurrent MS at the site of original disease. She was referred for localized RT and underwent salvage treatment in November 2014. The entire right breast was treated to a cumulative dose of 25 Gy in 10 fractions over 2 weeks, using a conformal RT technique with medial and lateral breast tangents. She tolerated her RT well, with no significant toxicity. She is now more than 10 years post-completion of salvage radiation, with no evidence of local recurrence or systemic relapse.

MS, commonly referred to as GS in the published literature, is a rare tumor located outside of the bone marrow and composed of immature myeloid cells [1-5]. It was first reported in 1811 by Allen Burns [8]. It was then attributed the term “chloroma” by King [9] in 1853 to describe the tumors greenish appearance (in Greek “chloros” means green) in the presence of myeloperoxidase stain. In 1902, Dock et al [10] reported the association between GS and AML. Approximately 2.5% to 9.1% of AML patients have concomitant GS [1, 3, 5, 11]. Nonetheless, GS can also be found in patients with chronic myeloid leukemia, myelodysplastic syndrome and other myeloproliferative diseases. It can also occur as an isolated tumor in absence of medullary involvement [1-5].

MS presenting as a breast mass and only involving the breast is quite rare, and therefore the prognosis and natural history are not well defined. Also, there are no standard treatment guidelines for the management of localized MS of the breast [2, 4]. Treatment modalities include systemic therapy with chemotherapy, and local therapy with surgical excision and/or RT. The majority of patients receive systemic chemotherapy, with or without local treatment [1-5]. This combination has shown high remission rates, although the prognosis is poor in cases of relapses with generally limited overall survival [3, 7]. We reviewed recent studies and compiled a table summarizing case reports from the past 10 years published in the English literature (Table 1) [2, 4, 12-21].

Click to view

Table 1. Recent Case Reports of Breast Myeloid Sarcoma (2014 - 2025): Clinical, Imaging, and Treatment Features

RT can play an important role in local disease control, palliation of symptoms and potentially increasing overall survival in some patients. Further, MS is known to be radiosensitive, and the successful use of low-dose RT (20 - 30 Gy with conventional fractionation) has been reported. Yet, specific total dose and fractionation have not been standardized [1, 3-5, 11, 22-24]. This report highlights the excellent outcome that can be achieved with the use of 2.5 Gy per fraction for MS involving the breast. Chak et al [22] studied the correlation between total RT dose and response to treatment among 33 patients suffering from symptomatic extramedullary involvement by non-lymphocytic leukemia treated at Stanford University Hospital. Patients who received less than 10 Gy had 18±9% probability of attaining a complete response, whereas those who received 10 to 19.99 Gy had 43±11%. Patients with response rates of 86±14% and 89±10% received 20 to 29 and over 30 Gy, respectfully. Therefore, Chak et al suggest at least 30 Gy in 15 fractions over a 3-week period to treat symptomatic lesions after failed response to chemotherapy [22].

Similarly, the efficacy of low-dose RT on chloroma patients was demonstrated by Bakst et al [3] in 2012. Local control was attained in 97% of the patients treated with a median dose of 20 Gy and median fraction size of 2 Gy. RT was well tolerated with an absence of significant toxicity. Bakst et al suggested that RT is useful for symptom palliation, consolidation following chemotherapy, and in patients who relapse after allogeneic transplant or after failure to response to chemotherapy. A dose of 24 Gy in 12 fractions is recommended [3].

Consistent with the other studies, Chen et al [5] showed that median dose RT of 20 Gy (range 6 - 35 Gy) in fractions of 1.5 - 3.5 Gy have a significant impact on complete remission (CR) and partial remission (PR). Of the 20 patients receiving RT, 13 (65%) responded with CR, five (25%) with PR and two (10%) maintained a stable disease. Furthermore, RT provided symptom relief in 19 patients: six during the treatment and 13 within the 3-months post-treatment [5]. This is supported by Oertel ed al [23] who demonstrated a CR in 32 out of 45 patients (71%) and PR in nine (20%) using a median dose of 26 Gy.

Although optimal dose remains uncertain, Bakst e al [11] recently provided specific recommendations concerning RT indications and dose selection. Consistent with other studies, Bakst et al stated that RT is indicated in patients with local MS, those with inadequate response to chemotherapy, with recurrence post-allogeneic stem cell transplant and for patients requiring symptom palliation. A low-dose RT regimen of 24 Gy in 12 fractions is suggested for most patients, providing long-term disease control without significant toxicity. Lower doses such as 6 to 20 Gy given in 2 Gy fractions are sometimes recommended in the setting of palliation in advanced stage disease [11].

While RT remains an effective local treatment for breast MS, particularly in achieving durable remission as highlighted in the current case, systemic management of residual disease or relapse remains challenging. In this context, emerging targeted therapies are gaining interest. Lessi et al [25] conducted a retrospective study where they showed the efficacy of FLT3 inhibitors, such as gilteritinib, in FLT3-mutated extramedullary AML, including isolated breast lesions. Venetoclax, a BCL-2 inhibitor, combined with hypomethylating agents, has also induced significant responses in breast MS, offering a potential alternative or adjunct to conventional chemotherapy (Jian et al [26], 2024). However, larger series and prospective studies are needed to better define the efficacy, safety, and optimal integration of these therapies in breast MS.

The case presented in the current study is a 33-year-old female diagnosed with a recurrent MS at the site of original disease in the right breast. She was treated with 25 Gy in 10 fractions over the course of 2 weeks, a dose corresponding to the recommendations in the literature. She tolerated her RT well and has now been in CR of her disease for more than 8 years.

There is currently no consensus in the treatment guidelines for MS, whether it is isolated or accompanying a hematological neoplasia. Treatment modalities include systemic therapy with chemotherapy, and local therapy with surgical excision and/or RT. The benefit of RT on disease- or progression-free survival has not been clearly described in the literature. However, low-dose RT between 20 and 30 Gy with conventional fractionation provides excellent local control and palliation of symptoms with minimal toxicity.

MS of the breast is a rare entity and often associated with a poor prognosis. Our case, in accordance with the literature, illustrates the efficacy of low-dose RT in treating a patient with relapsed MS of the breast without evidence of circulating leukemia cell or bone marrow infiltration. The salvage treatment of 25 Gy in 10 fractions over 2 weeks resulted in a lasting local remission with minimal toxicity. Future prospective studies or larger case series are needed to validate the efficacity of RT and optimize treatment strategies for isolated breast MS.

Acknowledgments

We thank all patients and clinical investigators who contributed to this study and made this research possible.

Financial Disclosure

None to declare.

Conflict of Interest

The authors declare no conflict of interest.

Informed Consent

Informed consent was obtained.

Author Contributions

JMB: conceptualization, manuscript drafting, and final approval. JG: literature review, manuscript drafting and editing. AM: literature review, manuscript drafting. CB: clinical input on hematologic aspects and manuscript review. RS: radiation oncology expertise and manuscript review.

Data Availability

The authors declare that data supporting the findings of this study are available within the article.

1. Dominguez Rullan JA, Fernandez Lizarbe E, Capuz B, Piris M, Sancho Garcia S. Radiotherapy for isolated granulocytic sarcoma: Case report and review of literature. Clin Transl Radiat Oncol. 2018;8:1-3.
   doi pubmed
2. Wu HY, Liu L, Gu L, Luo YH. Clinical characteristics and management of primary granulocytic sarcoma of the breast: A case report. Medicine (Baltimore). 2019;98(35):e16648.
   doi pubmed
3. Bakst R, Wolden S, Yahalom J. Radiation therapy for chloroma (granulocytic sarcoma). Int J Radiat Oncol Biol Phys. 2012;82(5):1816-1822.
   doi pubmed
4. Goncalves J, Louro LV, Ribeiro I, Oliveira A, Castro C. Radiotherapy for granulocytic sarcoma of the breast-Case report and review of the literature. Rep Pract Oncol Radiother. 2014;19(5):343-346.
   doi pubmed
5. Chen WY, Wang CW, Chang CH, Liu HH, Lan KH, Tang JL, Tien HF, et al. Clinicopathologic features and responses to radiotherapy of myeloid sarcoma. Radiat Oncol. 2013;8:245.
   doi pubmed
6. Dutta Roy S, Stafford JS, Scally J, Selvachandran SN. Granulocytic sarcoma of the breast antedating acute myelogenous leukemia. Breast. 2004;13(3):242-246.
   doi pubmed
7. Paydas S, Zorludemir S, Ergin M. Granulocytic sarcoma: 32 cases and review of the literature. Leuk Lymphoma. 2006;47(12):2527-2541.
   doi pubmed
8. Burns A. Observations on the surgical anatomy of the head and neck. Edinburgh: Bryce. 1811.
9. King A. A case of chloroma. Mon J Med. 1853;17:97.
10. Dock G, Warthin A. A new case of chloroma with leukemia. Trans Assoc Am Physicians. 1904;19:64-115.
11. Bakst RL, Dabaja BS, Specht LK, Yahalom J. Use of radiation in extramedullary leukemia/chloroma: guidelines from the international lymphoma radiation oncology group. Int J Radiat Oncol Biol Phys. 2018;102(2):314-319.
    doi pubmed
12. Huang XE, Li YJ, Zhou XD. Granulocytic sarcoma of the breast: a case report. Oncol Lett. 2015;10(4):2447-2449.
    doi pubmed
13. Ozsoy A, Akdal Dolek B, Barca N, Aktas H, Araz L, Kulacoglu S. Ultrasound findings in a case of myeloid sarcoma of the breast. J Belg Soc Radiol. 2016;100(1):15.
    doi pubmed
14. Sharma A, Das AK, Pal S, Bhattacharyya S. Fine-needle aspiration cytology of granulocytic sarcoma presenting as a breast lump - Report of a rare case with a comprehensive literature search. J Lab Physicians. 2018;10(1):113-115.
    doi pubmed
15. Zhai J, Kong X, Yang X, Gao J, Xuan L, Wang X, Wang J, et al. An uncommon granulocytic sarcoma of the breast: a case report and literature review. Onco Targets Ther. 2018;11:3685-3690.
    doi pubmed
16. Gomaa W, Ghanim A, Emam E, Bayoumi K, Ghanim A. Primary myeloid sarcoma of the breast: a case report and review of literature. J Microsc Ultrastruct. 2018;6(4):212-214.
    doi pubmed
17. Khoshnaw N, Yassin AK, Alwan AF, Hassan HA, Mula-Hussain L. Challenges associated with limited-resources cancer care facility: Bilateral breast myeloid sarcoma as an example. Clin Case Rep. 2019;7(11):2022-2026.
    doi pubmed
18. Kim SJ, Kim WG. Sonographic features of a myeloid sarcoma of the breast as a relapse of acute myeloid leukemia after stem-cell transplantation: a case report. Am J Case Rep. 2019;20:612-619.
    doi pubmed
19. Huang C, Fei S, Yao J, Chen P, Luo J, Wang Y, Li J, et al. Breast myeloid sarcoma presenting as a palpable breast lump after allogeneic stem cell transplantation for acute myelomonocytic leukemia: a rare case report. World J Surg Oncol. 2021;19(1):289.
    doi pubmed
20. Amiraian D, McDonough M, Geiger X. Bilateral myeloid sarcoma of the breast: a case report with radiological and pathological correlation. Cureus. 2022;14(5):e24731.
    doi pubmed
21. Mahfouz HE, Dheya N, Khalifa DS, Abdelhalim GY, Maisara NA, Saleh GA, Hamdy O, et al. Isolated breast myeloid sarcoma: A diagnostic and therapeutic challenge. A case report and literature review. Breast Dis. 2025;44:15581551251324069.
    doi pubmed
22. Chak LY, Sapozink MD, Cox RS. Extramedullary lesions in non-lymphocytic leukemia: results of radiation therapy. Int J Radiat Oncol Biol Phys. 1983;9(8):1173-1176.
    doi pubmed
23. Oertel M, Elsayad K, Haverkamp U, Stelljes M, Eich HT. Radiotherapy for extramedullary leukaemic manifestation (Chloroma). Strahlenther Onkol. 2018;194(2):164-173.
    doi pubmed
24. Majdoul S, Colson-Durand L, To NH, Belkacemi Y. Adaptive radiotherapy for an uncommon chloroma. Case Rep Oncol. 2016;9(3):593-598.
    doi pubmed
25. Lessi F, Borlenghi E, Sartor C, Vetro C, Audisio E, Vincenzo F, Visentin A, et al. PB1858: prognosis and treatment of FLT3 mutated myeloid sarcoma in the era of FLT3 inhibitors: retrospective evaluation in 5 Italian centers. Hemasphere. 2023;7(Suppl):e66479a1.
    doi
26. Jian X, Cha J, Lin Z, Xie S, Huang Y, Lin Y, Zhao H, et al. Real-world experience with venetoclax-based therapy for patients with myeloid sarcoma. Discov Oncol. 2024;15(1):210.
    doi pubmed

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial 4.0 International License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Journal of Medical Cases is published by Elmer Press Inc.