Baylor University Medical Center Proceedings April 2017 - 195

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.

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: aaron.belknap@baylorhealth.edu).
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