Published online before print April 19, 2007, 10.1148/radiol.2433060747
(Radiology 2007;243:752-759.)
© RSNA, 2007
Granulocytic Sarcoma of Bowel: CT Findings1
Eugene K. Choi, BA,
Hyun Kwon Ha, MD,
Seong Ho Park, MD,
Soon Jin Lee, MD,
Seung Eun Jung, MD,
Kyoung Won Kim, MD, and
Seung Soo Lee, MD
1 From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul 138-736, Korea (E.K.C., H.K.H., S.H.P., K.W.K., S.S.L.); the Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (S.J.L.); and the Department of Radiology, St Mary's Hospital, College of Medicine, Catholic University of Korea, Seoul (S.E.J.). Received April 28, 2006; revision requested June 23; revision received June 28; accepted July 21; final version accepted September 18.
Address correspondence to H.K.H. (e-mail: hkha{at}amc.seoul.kr).
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ABSTRACT
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Purpose: To evaluate retrospectively the computed tomographic (CT) findings of granulocytic sarcoma of the bowel.
Materials and Methods: The institutional review boards of all participating institutions approved this study and waived the requirement for informed consent. CT scans were retrospectively reviewed in eight patients (seven men, one woman; age range, 23–71 years; mean age, 46 years) with pathologically proved granulocytic sarcoma of the small and/or large bowel. CT findings were evaluated with regard to the sites, morphologic characteristics, and contrast material enhancement patterns of the lesions, along with other ancillary findings (ie, peritoneal and mesenteric infiltration, ascites, lymphadenopathy, bowel perforation, and obstruction).
Results: Eight patients had a total of 13 lesions in the bowel (of which eight were pathologically proved), involving the duodenum (n = 1), jejunum (n = 2), ileum (n = 5), sigmoid colon (n = 1), and rectum (n = 4); multifocal bowel lesions were noted in four patients. The lesion varied in shape, with wall thickening alone in three of 13 lesions, an intraluminal polypoid mass in four, an exophytic mass in one, and a combination of findings in five. Contrast material enhancement, relative to the back musculature, showed isoattenuation in seven lesions, hyperattenuation in four, and hypoattenuation in two. Five of eight patients had multiple peritoneal masses with diffuse mesenteric or peritoneal infiltration. Ascites was present in six of eight patients; lymphadenopathy (especially in the mesentery), in five; bowel perforation, in two; and bowel obstruction, in one.
Conclusion: Granulocytic sarcoma of the bowel is characterized by variability in shape and contrast enhancement and has a high predilection for mesenteric and peritoneal spread.
© RSNA, 2007
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INTRODUCTION
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Granulocytic sarcoma is an extramedullary solid tumor composed of myeloid precursor cells known to occur commonly in patients with acute myelogenous leukemia (AML) and less commonly in those with myelodysplastic syndrome, chronic myelogenous leukemia, or other myeloproliferative disorders. In initial reports, the tumor was referred to as a "chloroma" because of a characteristic greenish hue noted on exposure to air that is caused by high levels of the enzyme myeloperoxidase within immature myeloid cells (1). Although granulocytic sarcomas usually occur as an additional manifestation in a patient known to have leukemia, they may appear as a sign of AML in a nonleukemic patient at presentation, as a sign of impending blast crisis in chronic myelogenous leukemia or leukemic transformation in myeloproliferative or myelodysplastic disorders, or as an isolated manifestation, preceding onset in the marrow by months to years (2,3).
Granulocytic sarcomas have been described in virtually every organ system but have a particular predilection for soft tissue, bone, skin, lymph nodes, and the periosteum (4). Involvement of the gastrointestinal (GI) tract is uncommon. In one series, only four (7%) of 61 patients with granulocytic sarcoma had GI localization (4). Although the majority of granulocytic sarcomas are not generally associated with clinical signs, those of the GI tract are associated with serious complications, including hemorrhage, perforation, necrosis, obstruction, and intussusception (5). Granulocytic sarcomas of the GI tract can be an isolated manifestation in the absence of any hematologic disorder (3,6–8), thereby precluding an overt diagnosis of granulocytic sarcoma. Without the aid of such clinical clues, a familiarity with radiologic characteristics is critical for diagnosis. Moreover, patients with isolated granulocytic sarcoma of the GI tract who are treated with standard induction chemotherapy appear to have a substantially lower probability of subsequent development of AML (9–11). Therefore, awareness and prompt recognition of this disease entity is also of great clinical importance in the ongoing management of hematologic malignancies.
Descriptions of the imaging characteristics of granulocytic sarcoma of the GI tract have been limited to case reports (1–3,5,7,8,11–14), and, to our knowledge, there has been no evaluation of the imaging characteristics in a single series. In the two published reports of the imaging findings of granulocytic sarcoma (15,16), no patients with small- or large-bowel involvement were included. Because computed tomography (CT) is the principal imaging modality in the evaluation of the GI tract in patients with malignancy, the purpose of our study was to evaluate retrospectively the CT findings of granulocytic sarcoma of the bowel.
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MATERIALS AND METHODS
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Study Group
A computer search of the pathology, radiology, and medical records of three tertiary referral centers in Seoul, South Korea (Asan Medical Center, Samsung Medical Center, and St Mary's Hospital) was performed to identify pathologically confirmed cases of granulocytic sarcoma from January 1997 to December 2005. Of 55 patients with pathologically confirmed granulocytic sarcoma anywhere in the body, eight were found to have granulocytic sarcoma involving the GI tract, and these patients constituted our study cohort. The average patient age was 46 years (range, 23–71 years), and there were seven men and one woman. Pathologic evidence of granulocytic sarcoma of the bowel was provided by surgical resection in three patients, open biopsy in one, and endoscopic biopsy in four. The clinical indications for surgical intervention were bowel perforation, bowel obstruction, and resection for presumed small-bowel GI stromal tumor (each n = 1). The institutional review boards of all three institutions approved our study, and the requirement for patient informed consent was waived.
Clinical Findings
The patient's medical records were reviewed by one of the investigators (E.K.C.). Complete hematologic investigations, including bone marrow biopsy and aspiration, were performed in all patients. Clinical data were obtained, including presenting symptoms, leukemic history at presentation, and the chronologic development of granulocytic sarcoma in relation to hematologic diagnosis. The diagnosis of systemic myeloid leukemia was based on results of bone marrow examination. Granulocytic sarcoma was determined to be the presenting manifestation of the disease if the evidence of acute systemic leukemia was found at bone marrow biopsy within 1 month after the initial presentation of granulocytic sarcoma. If the diagnosis of systemic leukemia occurred more than 1 month after the presentation of the tumor, then the granulocytic sarcoma was deemed to have represented an isolated case preceding the diagnosis of acute leukemia. The surgical, endoscopy, and pathology reports were also reviewed, when available.
CT Imaging and Evaluation
Contrast material–enhanced abdominal CT was performed in all patients with a commercially available single- or multidetector scanner (Somatoform Plus-S, Somatom Plus IV, or Volume Zoom; Siemens, Erlangen, Germany; LightSpeed Qx/i; GE Medical Systems, Milwaukee, Wis). Each patient had received 100–120 mL of iopromide (Ultravist 300 or Ultravist 370; Schering, Berlin, Germany), administered at a rate of 3.0 mL/sec through an 18-gauge angiographic catheter inserted in an antecubital vein. CT scans were obtained approximately 65–70 seconds after administration of contrast material, with a collimation of 5–10 mm and a table pitch of 1:1. Seven of eight patients underwent three (n = 5) or four (n = 2) CT examinations over a mean period of 10.5 months (range, 1.4–19.1 months). The remaining patient underwent one CT examination, which was immediately followed by surgical resection.
CT scans were independently evaluated by three GI radiologists (H.K.H., K.W.K., S.S.L.). When their interpretations differed, they reached a consensus. On CT scans, the involved sites of the bowel were assessed and the bowel wall involvement patterns were analyzed. In the analysis of bowel wall involvement patterns, the morphologic appearance of the lesion was subjectively categorized as an intraluminal polypoid or exophytic mass or as bowel wall thickening. We also analyzed contrast enhancement patterns of the lesions and looked for the presence or absence of bowel obstruction or perforation, lymphadenopathy, ascites, lesions in other solid abdominal organs, and changes in the omentum, mesentery, and peritoneum. Given the difficulty of assessing the enhancement pattern of normal adjacent bowel wall segments, especially when distended, we compared the contrast enhancement of the GI lesion with that of the back musculature.
Infiltrative changes of the peritoneum, omentum, and mesentery were indicated by the following imaging features: haziness and increased attenuation of and stranding into the peritoneal fatty tissue. The degree of mesenteric and omental infiltration was categorized as localized or diffuse; the infiltrative process was considered localized when it was confined to the region surrounding the GI lesion and diffuse if it extended to distant sites. The presence and relative quantity of ascites were also assessed. The amount of ascites was considered small if it was limited to the pelvic cavity and large if it extended beyond the pelvic cavity. The presence and location of lymphadenopathy were assessed. Our size criterion for lymphadenopathy was a lymph node with a dimension of 1 cm at the longest axis. Consensus was required for the assessment of mass shape in three and lymphadenopathy in two of eight patients.
In the seven of eight patients who underwent serial CT examinations, we evaluated progression of disease process and/or its response to antileukemic therapy. Endoscopic images, available in four patients, were evaluated and correlated with CT findings by one investigator (E.K.C.).
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RESULTS
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Clinical Findings
The most common presenting symptom (Table 1) was abdominal pain (five of eight patients). Other presenting signs included GI bleeding (one patient), diarrhea, and vomiting. At presentation, five of eight patients did not have any known history of hematologic malignancy, two patients were known to have a history of AML, and one patient had chronic myelogenous leukemia. Of the five patients without a known history of leukemia, AML was ultimately diagnosed in four: on the day of presentation in patient 7 and 2 weeks, 1 month, and 1 month after presentation in patients 2, 5, and 8, respectively. The remaining patient did not have any evidence of systemic disease after a follow-up of 4 years, despite repeated bone marrow examinations. Granulocytic sarcoma was the presenting sign of acute leukemia in four patients (patients 2, 5, 7, and 8).
CT Findings
A total of 13 lesions in the bowel, presumed to represent granulocytic sarcoma, were noted in the eight patients (Table 2). The sites of bowel involvement included the duodenum (n = 1), jejunum (n = 2), ileum (n = 5), sigmoid colon (n = 1), and rectum (n = 4). Of those 13 lesions, five in the small intestine of five patients and three in the rectum of three patients were pathologically confirmed. The rectum was the primary site of involvement in only one patient; in the other three patients, it was the site of secondary tumor spread through the peritoneum. The bowel was the only abdominal solid organ involved, with the exception of the pancreas in one patient. (Complete resolution of a focal pancreatic mass after chemotherapy was highly suggestive of pancreatic involvement.) Multifocal bowel lesions were noted in four of eight patients.
Lesions in the GI tract were highly variable in shape (Figs 1–4), manifesting predominantly as wall thickening alone in three of 13 lesions, as an intraluminal polypoid mass in four, as an exophytic mass in one, and as a combination of these shapes in five. In two patients with multifocal lesions of the bowel, the individual lesions differed in shape. The enhancement of the lesions in the bowel was variable as well, with isoattenuation relative to the back musculature in seven lesions, hyperattenuation in four lesions, and hypoattenuation in two. Bowel obstruction was present in one patient, and bowel wall perforation was present in two.
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Figure 1: Patient 4. Contrast-enhanced transverse CT scan in 38-year-old man with no known history of leukemia and abdominal pain and diarrhea at presentation shows an exophytic mass (arrowheads) with bowel wall thickening causing small-bowel obstruction in the jejunum with a dilated duodenum (D) and proximal jejunum. This patient never had blood or bone marrow evidence of acute leukemia during 3 years of follow-up and was therefore considered to have isolated granulocytic sarcoma of the small bowel. Microscopic examination (results not shown) revealed leukemic tumor cell infiltration of mucosal surface. Immunohistochemical staining was positive for myeloperoxidase but negative for T-cell and B-cell markers (ie, CD3, CD20), indicating that the tumor cells were of myeloid origin and thus compatible with the diagnosis of granulocytic sarcoma.
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Figure 2a: Patient 2. Contrast-enhanced transverse CT scans in 48-year-old man with no known history of acute leukemia who presented with diffuse abdominal pain. (a) Initial CT scan shows a mass (arrow) and tumor infiltration of the mesentery. A mesenteric vessel (arrowhead) is situated within the mass. An intraluminal polypoid mass of high attenuation (not shown) was noted in the ileum. Exploratory laparotomy was performed for obstructive symptoms, and open lesion biopsy enabled diagnosis of granulocytic sarcoma. (b, c) Follow-up scans obtained 1 month later show large amount of ascites with enhancement of the peritoneum (black arrowheads in b), diffuse bowel wall thickening (white arrowhead in b), infiltration of the mesentery, and rapid interval development of diffuse mesenteric infiltration by soft tissue (arrowheads in c). (d, e) Second set of follow-up scans obtained 1 month after b and c, after chemotherapy, shows marked reduction of tumor dissemination with substantial resolution of ascites, infiltration of bowel wall and mesentery, and the tumor mass, which had once largely occupied the pelvic cavity. There remains some thickening of the bowel (arrowheads) and residual infiltration of the mesentery.
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Figure 2b: Patient 2. Contrast-enhanced transverse CT scans in 48-year-old man with no known history of acute leukemia who presented with diffuse abdominal pain. (a) Initial CT scan shows a mass (arrow) and tumor infiltration of the mesentery. A mesenteric vessel (arrowhead) is situated within the mass. An intraluminal polypoid mass of high attenuation (not shown) was noted in the ileum. Exploratory laparotomy was performed for obstructive symptoms, and open lesion biopsy enabled diagnosis of granulocytic sarcoma. (b, c) Follow-up scans obtained 1 month later show large amount of ascites with enhancement of the peritoneum (black arrowheads in b), diffuse bowel wall thickening (white arrowhead in b), infiltration of the mesentery, and rapid interval development of diffuse mesenteric infiltration by soft tissue (arrowheads in c). (d, e) Second set of follow-up scans obtained 1 month after b and c, after chemotherapy, shows marked reduction of tumor dissemination with substantial resolution of ascites, infiltration of bowel wall and mesentery, and the tumor mass, which had once largely occupied the pelvic cavity. There remains some thickening of the bowel (arrowheads) and residual infiltration of the mesentery.
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Figure 2c: Patient 2. Contrast-enhanced transverse CT scans in 48-year-old man with no known history of acute leukemia who presented with diffuse abdominal pain. (a) Initial CT scan shows a mass (arrow) and tumor infiltration of the mesentery. A mesenteric vessel (arrowhead) is situated within the mass. An intraluminal polypoid mass of high attenuation (not shown) was noted in the ileum. Exploratory laparotomy was performed for obstructive symptoms, and open lesion biopsy enabled diagnosis of granulocytic sarcoma. (b, c) Follow-up scans obtained 1 month later show large amount of ascites with enhancement of the peritoneum (black arrowheads in b), diffuse bowel wall thickening (white arrowhead in b), infiltration of the mesentery, and rapid interval development of diffuse mesenteric infiltration by soft tissue (arrowheads in c). (d, e) Second set of follow-up scans obtained 1 month after b and c, after chemotherapy, shows marked reduction of tumor dissemination with substantial resolution of ascites, infiltration of bowel wall and mesentery, and the tumor mass, which had once largely occupied the pelvic cavity. There remains some thickening of the bowel (arrowheads) and residual infiltration of the mesentery.
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Figure 2d: Patient 2. Contrast-enhanced transverse CT scans in 48-year-old man with no known history of acute leukemia who presented with diffuse abdominal pain. (a) Initial CT scan shows a mass (arrow) and tumor infiltration of the mesentery. A mesenteric vessel (arrowhead) is situated within the mass. An intraluminal polypoid mass of high attenuation (not shown) was noted in the ileum. Exploratory laparotomy was performed for obstructive symptoms, and open lesion biopsy enabled diagnosis of granulocytic sarcoma. (b, c) Follow-up scans obtained 1 month later show large amount of ascites with enhancement of the peritoneum (black arrowheads in b), diffuse bowel wall thickening (white arrowhead in b), infiltration of the mesentery, and rapid interval development of diffuse mesenteric infiltration by soft tissue (arrowheads in c). (d, e) Second set of follow-up scans obtained 1 month after b and c, after chemotherapy, shows marked reduction of tumor dissemination with substantial resolution of ascites, infiltration of bowel wall and mesentery, and the tumor mass, which had once largely occupied the pelvic cavity. There remains some thickening of the bowel (arrowheads) and residual infiltration of the mesentery.
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Figure 2e: Patient 2. Contrast-enhanced transverse CT scans in 48-year-old man with no known history of acute leukemia who presented with diffuse abdominal pain. (a) Initial CT scan shows a mass (arrow) and tumor infiltration of the mesentery. A mesenteric vessel (arrowhead) is situated within the mass. An intraluminal polypoid mass of high attenuation (not shown) was noted in the ileum. Exploratory laparotomy was performed for obstructive symptoms, and open lesion biopsy enabled diagnosis of granulocytic sarcoma. (b, c) Follow-up scans obtained 1 month later show large amount of ascites with enhancement of the peritoneum (black arrowheads in b), diffuse bowel wall thickening (white arrowhead in b), infiltration of the mesentery, and rapid interval development of diffuse mesenteric infiltration by soft tissue (arrowheads in c). (d, e) Second set of follow-up scans obtained 1 month after b and c, after chemotherapy, shows marked reduction of tumor dissemination with substantial resolution of ascites, infiltration of bowel wall and mesentery, and the tumor mass, which had once largely occupied the pelvic cavity. There remains some thickening of the bowel (arrowheads) and residual infiltration of the mesentery.
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Figure 3: Patient 3. Contrast-enhanced transverse CT scan in 71-year-old man. Chronic myelogenous leukemia had been diagnosed 18 months after a work-up of splenomegaly with abdominal pain and diarrhea. Scan shows 7.8-cm exophytic isoattenuating mass (white arrowheads) in duodenum, resulting in a compressed lumen (black arrow) with infiltration of the overlying omentum (curved white arrow). There is also evidence of ascites (black arrowhead) and peritoneal thickening (straight white arrow). Note enlarged spleen (*). Endoscopic view (not shown) of duodenal lesion demonstrated an irregular, exophytic fungating mass without any evidence of mucosal ulcerations.
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Figure 4a: Patient 5. Contrast-enhanced transverse CT scans in 42-year-old man without any known history of leukemia who presented with a palpable abdominal mass. (a) Initial CT scan shows jejunal lesion characterized by bowel wall thickening (black arrowheads) and an exophytic component (white arrowhead). There is also a soft-tissue mass (*) on mesenteric side of lumen that is continuous with primary lesion. This patient underwent surgical resection for suspected GI stromal tumor, and pathologic examination revealed granulocytic sarcoma. (b) CT scan at level of rectum shows soft-tissue mass (arrowheads) anterior to rectum in rectovescical pouch. Microscopic examination (results not shown) demonstrated leukemic cell infiltration of small bowel. (c, d) Follow-up CT scans obtained 2 months after a demonstrate worsening of leukemic dissemination with substantial omental (arrowheads in c) and mesenteric infiltration and rapid enlargement of the rectal soft-tissue mass (arrowheads in d). The patient did not receive any antileukemic treatment between the two CT examinations.
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Figure 4b: Patient 5. Contrast-enhanced transverse CT scans in 42-year-old man without any known history of leukemia who presented with a palpable abdominal mass. (a) Initial CT scan shows jejunal lesion characterized by bowel wall thickening (black arrowheads) and an exophytic component (white arrowhead). There is also a soft-tissue mass (*) on mesenteric side of lumen that is continuous with primary lesion. This patient underwent surgical resection for suspected GI stromal tumor, and pathologic examination revealed granulocytic sarcoma. (b) CT scan at level of rectum shows soft-tissue mass (arrowheads) anterior to rectum in rectovescical pouch. Microscopic examination (results not shown) demonstrated leukemic cell infiltration of small bowel. (c, d) Follow-up CT scans obtained 2 months after a demonstrate worsening of leukemic dissemination with substantial omental (arrowheads in c) and mesenteric infiltration and rapid enlargement of the rectal soft-tissue mass (arrowheads in d). The patient did not receive any antileukemic treatment between the two CT examinations.
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Figure 4c: Patient 5. Contrast-enhanced transverse CT scans in 42-year-old man without any known history of leukemia who presented with a palpable abdominal mass. (a) Initial CT scan shows jejunal lesion characterized by bowel wall thickening (black arrowheads) and an exophytic component (white arrowhead). There is also a soft-tissue mass (*) on mesenteric side of lumen that is continuous with primary lesion. This patient underwent surgical resection for suspected GI stromal tumor, and pathologic examination revealed granulocytic sarcoma. (b) CT scan at level of rectum shows soft-tissue mass (arrowheads) anterior to rectum in rectovescical pouch. Microscopic examination (results not shown) demonstrated leukemic cell infiltration of small bowel. (c, d) Follow-up CT scans obtained 2 months after a demonstrate worsening of leukemic dissemination with substantial omental (arrowheads in c) and mesenteric infiltration and rapid enlargement of the rectal soft-tissue mass (arrowheads in d). The patient did not receive any antileukemic treatment between the two CT examinations.
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Figure 4d: Patient 5. Contrast-enhanced transverse CT scans in 42-year-old man without any known history of leukemia who presented with a palpable abdominal mass. (a) Initial CT scan shows jejunal lesion characterized by bowel wall thickening (black arrowheads) and an exophytic component (white arrowhead). There is also a soft-tissue mass (*) on mesenteric side of lumen that is continuous with primary lesion. This patient underwent surgical resection for suspected GI stromal tumor, and pathologic examination revealed granulocytic sarcoma. (b) CT scan at level of rectum shows soft-tissue mass (arrowheads) anterior to rectum in rectovescical pouch. Microscopic examination (results not shown) demonstrated leukemic cell infiltration of small bowel. (c, d) Follow-up CT scans obtained 2 months after a demonstrate worsening of leukemic dissemination with substantial omental (arrowheads in c) and mesenteric infiltration and rapid enlargement of the rectal soft-tissue mass (arrowheads in d). The patient did not receive any antileukemic treatment between the two CT examinations.
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Multiple peritoneal masses were demonstrated in five of eight patients; peritoneal thickening was also present in most of these patients. Six patients had tumor infiltration of the mesentery beyond the region of leukemic bowel involvement. Diffuse infiltration of the omentum was seen in six patients, and mass replacement of the omentum (omental cake) was seen in three of these six patients. Serial CT examinations showed clear progression from an isolated bowel lesion to rapid infiltration of the mesentery and subsequent massive soft-tissue formation in three patients.
Ascites was present in six of eight patients, and the amount of ascites was considered large in two. Lymphadenopathy was demonstrated in six of eight patients, with the most commonly involved nodes being those in the mesentery (n = 5). Two patients with massive tumor involvement of the mesentery and peritoneum showed marked response to antileukemic therapy at follow-up CT (Figs 2, 4).
Endoscopic Findings
Endoscopic findings were available in one patient with granulocytic sarcoma of the duodenum and in all three patients with rectal involvement. The duodenal tumor appeared as a protruding, fungating mass, whereas the rectal tumors appeared either as a nodular thickening of the rectal wall or as an intraluminal polypoid mass.
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DISCUSSION
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Recognition of granulocytic sarcoma is clinically important because the condition affects the treatment regimen. If patients with no discernible hematologic abnormality at the time of diagnosis are treated with surgery in the absence of systemic chemotherapy, acute leukemia develops in up to 80%–90% of them at a mean of 11 months after diagnosis of granulocytic sarcoma (4). If patients are treated with standard induction chemotherapy at diagnosis, however, there is a substantially lower probability of AML, along with prolonged survival (9–11). There is evidence that addition of radiation therapy may also prolong survival (10). In addition, in accordance with findings of previous studies (4,7), the temporal association between the presentation of acute leukemia and granulocytic sarcoma was variable in our study. In our series, five patients did not have a history of leukemia at presentation, and granulocytic sarcoma was a presenting manifestation of leukemia in four of eight patients.
The most common primary site of involvement in our study was the small bowel, specifically the ileum; this is consistent with the finding of a previous study (3). On the other hand, isolated primary involvement of the colon and rectum is exceedingly rare; the colon and rectum seem to be more commonly involved through secondary extension from the peritoneum. To our knowledge, only three patients with isolated colonic (2,13,14) and two with rectal granulocytic sarcoma (12,17) have been described in the English-language literature.
The CT features of granulocytic sarcoma of the bowel are variable. Lesions appeared as an intraluminal or exophytic polypoid mass, as bowel wall thickening, or as a combination of these manifestations. The enhancement patterns of these lesions were also variable. Therefore, leukemic lesions of the bowel itself cannot be differentiated at CT from lymphoma or other neoplastic conditions or inflammatory bowel diseases.
Rather than bowel involvement patterns, the striking CT feature in our series was the rapidity and widespread extent of infiltration of the peritoneum, omentum, and mesentery, with subsequent soft-tissue mass formation. Six of our eight patients (75%) had CT evidence of diffuse infiltration or masses in the omentum and mesentery adjacent to the involved bowel. Despite our limited number of patients, our findings suggest that leukemia with primary bowel involvement has a high likelihood of diffuse peritoneal and omental involvement. However, because two of our six patients who presented with diffuse mesenteric or omental infiltration and peritoneal thickening also had CT evidence of bowel perforation, we could not rule out the possibility that peritonitis accounted for the CT findings, at least in part. In patients with leukemic peritoneal spread, secondary involvement of other areas of the GI tract is also common. Three of our four patients with rectal granulocytic sarcoma, for example, seemed to have secondary neoplasms arising from peritoneal involvement.
Lymphomatous involvement of the peritoneum has been termed peritoneal lymphomatosis, but a counterpart term for myeloid leukemic involvement is not known. Granulocytic sarcomatosis may be an appropriate term to describe the diffuse malignant changes of the peritoneum secondary to myeloid leukemic dissemination. It is important to understand the propensity of intestinal granulocytic sarcoma to engage the overlying peritoneum, given that the presence of multiple disseminated peritoneal masses, especially in a patient without a known history of leukemia, may be misdiagnosed as another condition (eg, peritoneal carcinomatosis, tuberculous peritonitis, or peritoneal lymphomatosis). Despite the aggressiveness of the tumor, it is highly responsive to antileukemic therapy (9–11), making its early recognition clinically important.
In our series, lymphadenopathy was most commonly noted in the mesentery, but enlarged nodes were small and discrete and did not adopt the bulky conglomerate soft-tissue masses that tend to encircle (but not obstruct) normal anatomic structures and are characteristically observed in B-cell non-Hodgkin lymphoma of the bowel (18).
The most common complications of intestinal granulocytic sarcoma reported in the literature include hemorrhage, perforation, necrosis, obstruction, and intussusception (5). In our series, bowel perforation was noted in two patients, and CT also demonstrated bowel hemorrhage in one of these patients. Both patients, however, had a history of chemotherapy. Bowel perforation in a patient with leukemia may result from weakening of the bowel wall secondary to leukemic invasion and/or toxic GI effects of chemotherapy followed by subsequent bacterial, fungal, or viral overgrowth (19). Bowel obstruction occurred in one patient. According to a review of the literature describing patients with granulocytic sarcoma of the small intestine through 1998 (3), symptoms of small-bowel obstruction occurred in eight of 10 patients, suggesting that such symptoms may be more common than in lymphomatous involvement of the bowel.
Our study had limitations. First, it included a small number of patients because of the rarity of the tumor in the GI tract. Second, pathologic confirmation was not obtained for every mass lesion observed in the bowel. However, the presence of at least one pathology-proved granulocytic sarcoma in the bowel in each patient provided compelling evidence that other morphologically similar bowel lesions represented the same disease. Finally, the absence of correlated imaging studies (ie, small-bowel follow-through studies, barium enema studies) makes it difficult to clarify the precise location and shape (in particular, the intraluminal component) of the bowel lesions. In conclusion, granulocytic sarcoma of the bowel is characterized by variability in shape and contrast enhancement and has a high predilection for mesenteric and peritoneal spread.
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ADVANCES IN KNOWLEDGE
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- Granulocytic sarcoma of the bowel is characterized by variability in shape and contrast enhancement and has a high predilection for mesenteric and peritoneal spread.
- Mesenteric infiltration by leukemic cells is characterized by rapid soft-tissue formation that shows marked resolution with antileukemic therapy.
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FOOTNOTES
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Abbreviations: AML = acute myelogenous leukemia • GI = gastrointestinal
2 Current address: Department of Radiology, Weill Medical College of Cornell University, New York, NY. 
Authors stated no financial relationship to disclose.
Author contributions: Guarantors of integrity of entire study, E.K.C., S.S.L.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, E.K.C.; clinical studies, all authors; and manuscript editing, all authors
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J. Skucas, E. K. Choi, and H. K. Ha
Granulocytic Sarcoma of Bowel
Radiology,
February 1, 2008;
246(2):
651 - 651.
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ABSTRACT
INTRODUCTION
