A 69-year old black woman presented with profound anemia, with hemoglobin of 5.8mg/dL. A bone marrow aspiration biopsy was consistent with myelofibrosis and myeloid metaplasia.
Prepared by Chandana Lall, MD, Department of Radiology;
Fleurette Abreo, MD, Department of Pathology; Cherie Ann
Nathan, MD, Department of Otolaryngology; and Girish Agrawal,
MD, Department of Radiology, Louisiana State University Health
Sciences Center and the Feist Weiller Cancer Center,
Shreveport, LA.
CASE SUMMARY
A 69-year-old black woman whose first hospital admission was in
September 1999 presented with profound anemia, with hemoglobin of
5.8 mg/dL. A bone marrow aspiration biopsy was consistent with
myelofibrosis and myeloid metaplasia. The patient complained of
abdominal pain and fullness, as well as dyspnea on exertion for the
prior 6 days. Past medical history was significant for coronary
artery disease.
Admission laboratory work-up revealed normal sequential multiple
analyzer 7 values; admission blood gas was 7.42. A complete blood
count showed a white count of 113,000, hemoglobin/hematocrit of 6.7
and 23.1, a platelet count of 449, and mean corpuscular volume of
93.9. Differential on white count was 64% neutrophils, 6% bands,
and 7% lymphocytes.
DIAGNOSIS
Agnogenic myeloid metaplasia presenting with omental implants
and ascites
IMAGING FINDINGS
Radiological work-up consisted of flat and upright abdominal
radiographs, an abdominal ultrasound, as well as a computed
tomogram (CT) of the abdomen and pelvis.
Ultrasound revealed massive hepatosplenomegaly without focal
solid lesions, an incidental 4-cm hepatic cyst, and moderate volume
ascites (figure 1). Abdominal and pelvic CT scan showed, in
addition to significant hepatosplenomegaly, moderate volume ascites
and mesenteric engorgement, as well as peritoneal thickening and
multiple discrete omental implants (figures 2 and 3).
Considering the patient's postmenopausal status and older age,
and her ascites and peritoneal implants, the possibility of
metastatic ovarian carcinoma was high in the differential
diagnosis. The patient was referred for CT-directed biopsy of the
omental implants.
The pathology findings were as follows: fine-needle aspiration
biopsy (FNAB) of the omental infiltrate (Wright stain 400x/600x)
showed a significantly increased number of myeloid precursors
(figure 4).
DISCUSSION
The terms "myeloid metaplasia" and "extramedullary
hematopoiesis" are used to describe a pathologic process of ectopic
hematopoietic activity that may occur in any organ system but that
primarily affects the liver and spleen.
1
Myeloid metaplasia is not always associated with myelofibrosis, and
either of these processes may occur in the absence of a clonal
hematological disorder.
2,3
The incidence of agnogenic myeloid metaplasia is between 0.5 and
1.5/100,000 population,
4,5
with an increased prevalence in Ashkenazi Jews. Median age at
diagnosis is approximately 65 years with no sex predilection.
6
An initial clue to the diagnosis of myelofibrosis is myelophthisis
of the blood, characterized by the presence of leukoerythroblasts
(immature granulocytes and nucleated red blood cells).
Clinically, patients usually present with profound fatigue,
weight loss, night sweats, low-grade fever, and marked
splenomegaly, the latter related to extramedullary hematopoiesis.
Anemia is present and is usually multifactorially related to
ineffective erythropoiesis, erythroid hypoplasia, and
hypersplenism.
7
Agnogenic myeloid metaplasia can present with several
complications, including portal hypertension, associated with
ascites or variceal bleeding. This is seen in approximately 7% of
patients
8
and may be related both to increased portal flow due to marked
splenomegaly and to intrahepatic obstruction due to thrombotic
obliteration of small portal veins.
9
Splenic infarction may also occur, but episodes are usually
self-limited. Refractory cases may require splenectomy or splenic
irradiation.
Extramedullary hematopoiesis may occur at sites other than the
spleen, including lymph nodes and serosal surfaces, leading to
effusions and ascites in the lungs causing a pneumonia-like
process, etc. This phenomenon has also been reported in the
paraspinal and epidural spaces, leading to spinal cord and nerve
root compression. Extramedullary hematopoiesis not involving the
liver or spleen is usually managed with low-dose external beam
irradiation.
10
A case of agnogenic myeloid metaplasia with pericardial
extramedullary hematopoiesis presenting as acute cardiac tamponade
has been reported. To our knowledge, a case of agnogenic myeloid
metaplasia presenting with omental implants has not been reported
in the radiology literature.