Granulocytic sarcoma (GS) is seen in ~5% of myeloid leukemia cases and represents the "tissue phase" of the disease. GS can also be seen in patients with chronic myeloproliferative disorders or myelodysplastic syndromes (MDS).[1,2] It antedates the development of acute myeloid leukemia (AML) by about 1 to 2 years.[2] Common sites of involvement include the skin, gums, lymph nodes, soft tissues, periosteum, and bone. Involvement of the gastrointestinal (GI) tract is very rare and commonly involves the small intestine presenting with intestinal obstruction or perforation.[3-5] Gastric GS may occur as gastric ulcers or polyps, and patients most often present with an acute GI bleed.[4-6]

Well-differentiated GS consists of tumor cells of myeloid origin showing various stages of maturation. The specific esterase stain, chloroacetate esterase (also called Leder stain), stains neutrophils, neutrophil precursors, eosinophils, and mast cells and confirms the granulocytic nature of the tumor. Various karyotypic abnormalities are seen in primary GS or AML with GS such as t(8,21), 11q23, and inv(16).[7-9] Molecular analysis such as fluorescence in situ hybridization (FISH) can also help detect specific cytogenetic abnormalities.

Treatment for GS should be directed toward the underlying hematologic disorder, but there is no standard treatment. Treatment of symptomatic GI tract GS poses a special challenge. Most physicians treat granulocytic sarcoma as AML using standard chemotherapy regimens.[10] However, care should be taken to avoid premature induction therapy, since treatment of MDS-associated GS does not prolong survival. Patients with MDS, who develop GS as a marker of disease acceleration and transformation to AML, have a poor prognosis and survival despite aggressive chemotherapy.[11,12]

Case Report

A 67-year-old woman was diagnosed with refractory anemia with excess blasts II (RAEB II, 13%) in 2005. She was treated on protocol with thalidomide (Thalomid) and azacitadine (Vidaza). Upon disease progression, she enrolled in another clinical trial and was treated with a monoclonal antibody to CD33. While on treatment she presented with a 1-week history of melena, nausea, decreased appetite, abdominal pain, weight loss, and fatigue. She was hypotensive and tachycardic, with abdominal tenderness and splenomegaly. Her hematocrit was 20%, hemoglobin 6 g/dL, platelet count 59,000/mm3, and white blood cell count 71,000 /mm3, with 9.3% blasts on the peripheral smear.

She was admitted to the intensive care unit in February 2007 and was initially thought to have GI bleeding secondary to thrombocytopenia, and platelet dysfunction secondary to MDS. She received a platelet transfusion. Because of the abdominal pain, splenomegaly, and low hematocrit on the initial presentation, a computed tomography scan of the abdomen was performed, showing a 6.4 — 5.5 cm mass in the gastric antrum, massive splenomegaly of 21.5 — 8.5 cm, and extensive lymphadenopathy (Figure 1).

 

Figure 1 Figure 2 Figure 3
Figure 1: CT Scan of the Abdomen—Computed tomography (CT) scan of the abdomen showing a mass in the gastric antrum, massive splenomegaly, and extensive lymphadenopathy. Figure 2: Endoscopic Image—Endoscopy revealing a large submucosal, noncircumferential mass in the gastric antrum. Figure 3: Pathologic Findings—Biopsy showing an atypical cellular infiltrate of myelocytes, neutrophils, and lymphocytes with convoluted monocytoid nuclei, which stained positive for CD43, lysozyme, myeloperoxidase, and Leder stain.


 
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