Clinical case
A 32-year-old male without any previous medical history initially
presented to our outpatient hematology department with a 1-month history
of progressive weakness, dyspnea, and intermittent fever. Physical
examination revealed petechiae on the upper extremities and thorax. The
peripheral blood cell count showed the following results: white blood
cell count (WBC), 75.8 × 109/l with 42% blast cells,
hemoglobin level of 7.2 g/dl, and a platelet count of 54 ×
109/l. Subsequent bone marrow aspiration revealed a
hypercellular bone marrow with a significant increase in cells
displaying morphological features consistent with myeloblasts (fig. 1).
Larger cells with more abundant basophilic cytoplasm and scattered
granules were also observed, suggestive of monocytic differentiation. A
diagnosis of AML, subtype M4 (Acute Myelomonocytic Leukemia) by the
French-American-British (FAB) classification, was established.
Standard induction chemotherapy was initiated with an
anthracycline-based 7+3 regimen containing doxorubicin and cytarabine.
After the first cycle, repeat bone marrow aspiration showed no blast
cells, and the complete blood count (CBC) revealed a hemoglobin level of
10.6 g/dl, platelet count of 204 × 109/l, and WBC
count of 6 × 109/l with a normal differential,
indicating complete remission with hematologic recovery. Additionally, a
lumbar puncture (LP) was performed due to the high WBC count at
diagnosis and signs of monocytic differentiation serving as additional
risk factors for CNS involvement. The cerebrospinal fluid (CSF) analysis
was unremarkable for signs of disease.
Post-remission therapy consisted of three additional consolidation
cycles of the same regimen, followed by monthly surveillance. After
approximately 16 months of CR, the patient presented to a local
otolaryngology department with complaints of left-sided otalgia, hearing
loss and fever. Otoscopic examination revealed a narrowed left external
auditory canal with ipsilateral hyperemia and purulent otorrhea
obscuring the tympanic membrane. Examination of the right side was
unremarkable, with an intact external auditory canal and tympanic
membrane. Bilateral mixed hearing loss was confirmed by audiometry. At
the time, the CBC results did not show any signs of systemic AML, except
for a slight leukocytosis with a left-shift deviation suggestive of an
inflammatory process. Likewise, the CSF examination indicated no
evidence of leukemic cells. Based on presentation and symptoms, a
presumptive diagnosis of acute otitis media and externa was made, and
the patient was prescribed oral antibacterial therapy. However, after
one week of treatment, there was no symptomatic improvement.
A computed tomography (CT) scan was conducted (fig. 2), revealing a
narrowed left external auditory canal and non-specific bilateral
opacification of the middle ear cavities and the mastoid cells with
increased soft tissue density, which was particularly notable on the
left side. Importantly, the mastoid structure appeared intact, with no
apparent areas of bone destruction and distinct masses. Taking into
account the clinical presentation and imaging findings, a provisional
diagnosis of acute bilateral otomastoiditis was made. Due to the
worsening of the symptoms and refractoriness to conservative therapy, a
left-sided mastoidectomy was performed with a curative intent (fig. 3).
On visual inspection, the mastoid fragment contained no soft tissue.
The subsequent pathological review of the mastoid structure demonstrated
extensive effacement with a homogeneous population of atypical cells,
characterized by irregular nuclei, fine chromatin, prominent nucleoli,
and scant cytoplasm (fig. 4). Importantly, these findings were at odds
with the absence of leukemic cells in the blood, bone marrow and CSF. An
initial diagnosis of Burkitt’s lymphoma was considered; however, further
immunohistochemistry profiling showed positive staining for
myeloperoxidase, CD34, TdT, CD117, CD68, and negative staining for CD3,
CD20, PAX5, ALK, and Desmin. These results were consistent with the
presence of blast cells of the myeloid lineage. Consequently, a final
diagnosis of relapsed AML presenting as an isolated myeloid sarcoma of
the temporal bone was confirmed.
Following the surgical intervention, the patient made a full recovery
with significant symptom relief. Approximately 3 months have passed
since the initial presentation, during which neither the CBC, nor the
bone marrow examination showed signs of leukemic involvement. As such,
combined treatment with local radiation (28 Gy) and intrathecal
chemotherapy with cytarabine, methotrexate and dexamethasone was
attempted.
However, by the end of radiation therapy, the patient presented once
again with fever and progressive weakness. The CBC revealed a hemoglobin
level of 12.4 g/dl, platelet count of 74 × 109/l and a
WBC count of 4.2 × 109/l with 8% blast cells.
Subsequent bone marrow aspiration confirmed systemic relapse, with 56%
blast cells. Reinduction was attempted using the previously successful
induction regimen; however, after two cycles, the patient failed to
achieve remission.