About the lead author:
Charlton A. Smith, MD
Department of Radiation Oncology
National Institutes of Health
Radiation therapy (RT) is often used in combination with chemotherapy for myeloid sarcoma (also known as granulocytic sarcoma or chloroma). In certain clinical situations, it may be appropriate to use RT as a primary treatment, and it has been used in select cases for isolated tumors, particularly those that require rapid symptom relief. Here we describe our experience of treatment of myeloid sarcoma in the porta hepatis with RT alone. This appears to be the only reported case of primary radiation management of a hepatic myeloid sarcoma.
Materials and Methods
In this case report, we evaluated a 50-year-old woman with a newly diagnosed myeloid sarcoma at the porta hepatis. The patient had a known GATA2 mutation with monocytopenia and mycobacterial infection (Mono-Mac) syndrome, and a history of myelodysplastic syndrome-refractory anemia with excess blasts. She had had an unrelated hematopoietic stem cell transplantation (HCST) 1.5 years prior. Her post-transplant course was complicated by skin and gut graft-versus-host disease that required prolonged oral steroids and extracorporeal phototherapy. On presentation, she had a primary biliary obstruction that was initially treated with common bile duct stenting. However, the mass was found to invade and reobstruct the stent. At the time of evaluation for radiation, she was recovering from obstruction-induced cholangitis and sepsis; she had no myeloid disease involvement on bone marrow biopsy. After multidisciplinary evaluation, we elected to use the recently proposed low-dose radiation regimen of 24 Gy in 12 fractions. We designated our gross target volume (GTV) as areas concerning for disease involvement on computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET). We designated our clinical target volume (CTV) as a uniform 1-cm expansion on the GTV, and our planning target volume (PTV) as an additional 5-mm uniform expansion to the CTV. We delivered 24 Gy over 12 fractions using intensity-modulated radiation therapy.
We observed a total radiographic response 1 month after treatment, along with improvement in the patient’s symptoms and liver function tests. Six months after treatment there was no evidence of myeloid disease involvement on bone marrow cytopathology and cytogenetics. Unfortunately, she had a perirectal reoccurrence of the myeloid sarcoma at 10 months, representing an out-of-field reoccurrence. The bone marrow remained normal. This recurrence was proximal to a site of prior RT induced enteric fistula following brachytherapy with cesium for cervical cancer; thus, we were unable to re-treat this site with RT. The patient underwent re-induction chemotherapy for a second HCST, however she died of multi-organ failure one month later, 11 months following RT for the porta hepatis myeloid sarcoma.
From our experience, treating myeloid sarcoma at the porta hepatis with 24 Gy over 12 fractions is a well-tolerated treatment that achieved a complete, durable response with minimal toxicity. We propose that clinicians consider radiation as a primary treatment option in clinical situations such as the one described here.
Myeloid sarcoma (also known as granulocytic sarcoma or chloroma) is a rare, extramedullary tumor of immature myeloid cells. The word chloroma comes from the Greek chloros, meaning green, and derives from the presence of myeloperoxidase. Not all deposits exhibit the characteristic green tint, so the terms “myeloid” or “granulocytic sarcoma” are now more commonly used.1
Myeloid sarcomas can present synchronously, after, and, rarely, prior to the onset of leukemia.
Most often, myeloid sarcoma is found concurrently in a patient with previously or recently recognized acute myeloid leukemia (AML) and is often considered an AML equivalent in terms of disease trajectory even when the bone marrow is uninvolved.2
The low frequency of presentation, frequent misdiagnosis, and the variable location and symptomatology have resulted in limited reported clinical experience. Historically, the role of radiation therapy (RT) for patients with myeloid sarcoma has been to provide timely symptom palliation.