Agnogenic myeloid metaplasia presenting with omental implants and ascites

Chandana Lall, MD; Fleurette Abreo, MD; Girish Agrawal, MD; Cherie Ann Nathan, MD

View content online at: http://www.appliedradiology.com/Issues/2001/09/Cases/Agnogenic-myeloid-metaplasia-presenting-with-omental-implants-and-ascites.aspx

Abstract:  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.

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Diagnosis

Agnogenic myeloid metaplasia presenting with omental implants and ascites

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 patients8 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.

1. Ward HP, Block MH. The natural history of agnogenic myeloid metaplasia and a critical evaluation of its relationship with the myeloproliferative syndrome. Medicine. 1971;50:357-420.

2. Moran CA, Suster S, Fishback N, Koss MN. Extramedullary hematopoiesis presenting as a posterior mediastinal mass: A study of four cases. Mod Pathol. 1995;8:249-251.

3. McCarthy DM. Fibrosis of the bone marrow: Content and causes. Br J Hematol. 1985;59;1-7.

4. McNally RJ, Rowland D, Roman E, Cartwright RA. Age and sex distributions of hematologic malignancies in the UK. Hematol Oncol. 1997;15:173-189.

5. Mesa RA, Silverstein MN. Population based incidence and survival figures in essential thrombocytopenia and agnogenic myeloid metaplasia. Am J Hematol. 1999; 61:1-5.

6. Kvasnicka HM, Thiele J, Werdec C. Prognostic factors in idiopathic osteomyelofibrosis. Br J Hematol. 1984;56:163-170.

7. Thiele J, Windeckee R, Kvasnicka HM, et al. Erythropoiesis in primary (idiopathic) osteomyelofibrosis: Quantification, PCNA-reactivity, and prognostic impact. Am J Hematol. 1994;46(1):36-42.

8. Silverstein MN, Wollager EE, Baggenstoss AH. Gastrointestinal and abdominal manifestations of agnogenic myeloid metaplasia. Arch Internal Med. 1973;131:532-537.

9. Wanless IR, Peterson P, Das A, et al. Hepatic vascular disease and portal hypertension in polycythemia vera and agnogenic myeloid metaplasia: A clinicopathologic study of 145 patients examined at autopsy. Hepatology. 1990;12:1166-174.

10. Bartlett RP, Greipp PR, Tefferi A, et al. Extramedullary hematopoiesis manifesting as a symptomatic pleural effusion. Mayo Clin Proc. 1995;70:1161-1164.

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.