Isolated Enteric Myeloid Sarcoma as a Rare Etiology of Small Bowel Obstruction in a Young Female Patient

Abstract

Myeloid sarcoma (MS) is an extra-medullary solid tumor consisting of myeloid blasts or immature myeloid cells. MS is usually associated with acute myeloid leukemia (AML) and other myeloproliferative neoplasms or myelodysplastic disorders. Isolated MS is a rare clinical entity, and the small bowel is a rare phenomenon for the occurrence of MS. A 30-year-old African American female patient with a past medical history of asthma presented with acute abdominal pain and vomiting for 3 days. Imaging revealed small bowel obstruction with a transition point at a suspicious mass in the distal ileum mimicking carcinoid tumors. She underwent an uneventful laparoscopic resection of this mass with primary bowel anastomosis. Histopathology of the resected mass revealed immature myeloid cells that stained positive for myeloperoxidase and CD34/CD117, in keeping with a small bowel MS. A bone marrow examination was negative for concurrent AML. Cytogenetic analysis revealed MYH11/CBFB fusion and an inversion 16 chromosomal aberration which are rarely associated with myeloid disorders. The patient was commenced on systemic chemotherapy to achieve remission and prevent progression to AML. The literature is reviewed, and all cases of small bowel MS are presented in this report. Non-leukemic small bowel MS is an exceptional presentation. We described a case of isolated enteric MS, which was associated with a rare MYH11/CBFB fusion and inversion 16 chromosomal aberration. The diagnosis of small bowel MS can be extremely challenging due to the rarity of the disease and non-specific nature of clinical and radiological features. A histopathological examination with immunohistochemistry staining is imperative to establish an accurate diagnosis. Isolated small bowel MS deserves special attention as it warrants systemic chemotherapy to prevent transformation into AML.

Keywords: Acute myeloid leukemia; Chemotherapy; Myeloid sarcoma; Rare etiology; Small bowel obstruction.

Figure 1

Axial (a) and coronal (b) images of CT of abdomen revealing mildly dilated small bowel loops with a transition point to the right of the midline (red arrow in a) in an area of a spiculated mass in the distal ileum simulating carcinoid tumors (red stars in a and b). CT: computed tomography.

Figure 2

Hematoxylin and eosin-stained sections of the small bowel mass. (a) Diffuse transmural infiltration with a dense population of polymorphous medium and large-sized immature cells with scant eosinophilic cytoplasm (× 2). (b, c) Immature neoplastic cells with rounded hyperchromatic nuclei and scattered eosinophils (× 200).

Figure 3

Immunohistochemistry staining of myeloid cells (× 200). Positive staining with myeloperoxidase (a) and CD34 (b).