Myeloid sarcoma causing airway obstruction
Aaron R. Belknap, MD, and John R. Krause, MD
Myeloid sarcoma is an extramedullary collection of blasts of the myeloid
series that partially or totally effaces the architecture of the tissue in which
it is found. These tumors have been described in many sites of the body, but
the skin, lymph nodes, gastrointestinal tract, bone, soft tissue, and testes
are most common. They can arise in a patient following the diagnosis of
acute myeloid leukemia, but they may also be precursors of leukemia and
should be considered diagnostic for acute myeloid leukemia. The differential
diagnosis of this neoplasm includes malignant lymphoma, with which it is
often mistaken, leading to diagnostic and therapeutic delays. We present the
case of an 84-year-old African American man with a history of renal disease
secondary to hypertension and coronary artery disease without any prior
history of malignancies who presented with airway obstruction. He was diagnosed with a myeloid sarcoma of the mediastinum compressing his trachea.
M
yeloid sarcoma, also known as granulocytic sarcoma,
extramedullary myeloid leukemia, or chloroma, is the
soft tissue equivalent of acute myeloid leukemia. It is
found in less than 1% of patients with acute myeloid
leukemia (1), but can also be found as a precursor lesion in patients
who have not been diagnosed with acute myeloid leukemia. In
up to 47% of patients, myeloid sarcoma is initially misdiagnosed
as malignant lymphoma (2). It is important to properly diagnose
this entity because it should be treated as acute myeloid leukemia.
We present the case of an 84-year-old man with no prior history of
malignancies presenting with airway obstruction, initially believed
to be caused by non-Hodgkin lymphoma, that was treated unsuccessfully with steroids while the biopsy was being evaluated. The
biopsy of the lesion was diagnosed as a myeloid sarcoma.
CASE REPORT
An 84-year-old man with previous end-stage renal disease,
type 2 diabetes mellitus, hypertension, and coronary artery disease
presented with dyspnea that had progressively worsened over a
3-week period. The dyspnea was present at rest and worsened in
the supine position. He had a mild cough with minimal sputum
production. Additionally, the patient had recently noticed that his
appetite had decreased and he had been losing weight. He did not
have fever or night sweats.
A chest computed tomography scan showed a superior
mediastinal mass measuring up to 7.3 cm in greatest dimension.
Proc (Bayl Univ Med Cent) 2017;30(2):195–196
Figure 1. Computed tomography image showing compression of the trachea
(arrowhead) by a soft tissue mass (arrows). A calcified left thyroid nodule (star)
extended into the mass.
It entirely encased the trachea and narrowed the lumen to 4 mm
at one point (Figure 1). The mass also compressed the right
brachiocephalic vein and the upper third of the esophagus. The
patient’s white blood cell count was 2.2 K/μL; hemoglobin,
10.4 g/dL; hematocrit, 33.3%; and platelets, 81 K/μL.
A biopsy of the mediastinal mass disclosed large atypical
discohesive cells percolating through a background of sclerotic
tissue. Most cells had prominent nucleoli, and a few cells had
small indistinct granules. On initial morphologic assessment, the
mass was most likely a lymphocytic neoplasm, and a diffuse large
cell lymphoma was considered. A battery of immunostains (CD3,
CD20, CD10, BCL-1, BCL-2, BCL-6, Mum-1, cMyc, Ki-67,
EBER, CD34, CD79a, CD4, and CD30) was performed, but of
these stains only BCL-2 (90%), CD34 (100%), and Ki-67 (40%–
45%) were positive. Additional stains (pancytokeratin, TdT, myeloperoxidase, CD15, CD68, and CD33) were performed to
From the Department of Pathology (Belknap) and Division of Hematopathology
(Krause), Baylor University Medical Center at Dallas and the Charles A. Sammons
Cancer Center, Dallas, Texas.
Corresponding author: Aaron R. Belknap, MD, Department of Pathology, Baylor
University Medical Center at Dallas, 3500 Gaston Avenue, Dallas, TX 75246
(e-mail: [email protected]).
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involvement to airway obstruction
from a mediastinal mass (6, 7). Due
to the broad range of symptoms that
can be caused by primary myeloid
sarcoma, a high index of suspicion is
necessary to avoid missing or delaying
this diagnosis.
These lesions often are initially diagnosed or worked up and treated as
a lymphoma. In our case, the patient
initially was treated with high-dose
steroids for presumed lymphoma
while the tissue was being examined
by pathology. The first suspicion that
this might be a myeloid sarcoma came
Figure 2. (a) Hematoxylin and eosin stain showing cells with prominent nucleoli. (b) Myeloperoxidase immunohistochemical when the initial round of immunostain showing positive-staining cells.
histochemical stains, which were
designed to identify a high-grade lymphoma, failed to establish that diagnosis. On the day of marrow
elucidate the origin of the tumor cells, and myeloperoxidase, TdT,
biopsy, the clinical team visited pathology to discuss the failure of
CD15, and CD33 were positive (Figure 2). With this immunothe patient to respond to high-dose steroids. Further immunohisstaining profile, the tumor was diagnosed as a myeloid sarcoma.
tochemical stains for myeloid sarcoma were ordered and the correct
The patient then had a bone marrow biopsy that showed 25%
diagnosis was established. It is important to distinguish between a
cellularity with trilineage hematopoiesis and only 1% myeloblasts
large-cell lymphoma and a myeloid sarcoma for treatment purposes.
by morphology, 1% to 2% by CD34 immunohistochemistry,
Acute myeloid sarcomas are generally treated in the same
and no evidence of a high-grade hematopoietic neoplasm by flow
manner as acute myeloid leukemia. Overall prognosis is extremecytometry. Mild megakaryocytic dyspoiesis was identified. A myely poor, with a median survival of 9.5 months; this includes both
lodysplastic syndrome fluorescence in situ hybridization study
primary and secondary myeloid sarcomas (8). One older series
on the patient’s bone marrow came back positive for deletions of
of 90 patients with primary myeloid sarcoma showed a median
chromosomes 5q and 20q in 74% and 22% of the cells examined,
survival of 22 months (9). Due to the numerous locations in
respectively, which is sufficient in the context of refractory cytowhich myeloid sarcoma can present, it is likely that the prognosis
penia for a presumptive diagnosis of myelodysplastic syndrome,
is largely dependent on the location and symptoms.
even in the absence of overt morphologic evidence.
The patient remained intubated without any clinical im1. Dores GM, Devesa SS, Curtis RE, Linet MS, Morton LM. Acute leukemia
provement following high-dose corticosteroid therapy. Due to
incidence and patient survival among children and adults in the United
the patient’s multiple comorbidities and age, chemotherapy was
States, 2001-2007. Blood 2012;119(1):34–43.
considered to be detrimental to the patient. By request of the
2. Yamauchi K, Yasuda M. Comparison in treatments of nonleukemic
family, he was transferred to the local Veteran’s Administration hosgranulocytic sarcoma: report of two cases and a review of 72 cases in the
pital, intubated, and sedated without plans for further treatment.
literature. Cancer 2002;94(6):1739–1746.
a
b
3.
DISCUSSION
This patient developed a myeloid sarcoma likely arising in a
lymph node or the soft tissue of the mediastinum leading to immediately life-threatening airway obstruction. Myeloid sarcoma is an
extremely aggressive extramedullary manifestation of acute myeloid
leukemia. Primary myeloid sarcoma, defined as myeloid sarcoma
without evidence of acute myeloid leukemia in the bone marrow, is
rare (3). It is generally considered a precursor lesion for acute myeloid
leukemia; one series prior to the advent of effective chemotherapy
showed 29 of 30 cases progressing to overt acute myeloid leukemia
in a median time of 7 months (4). Granulocytic sarcomas have been
described in myelodysplastic and myeloproliferative disorders (5).
Previous case reports of myeloid sarcomas described compression-related symptoms as the initial presentation. The symptoms
can vary dramatically based on the site of presentation, ranging
from back pain and bilateral leg weakness from spinal cord compression to intestinal obstruction and appendicitis from mesenteric
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Baylor University Medical Center Proceedings
Volume 30, Number 2