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A 53-year-old male veteran with a history of heavy tobacco and alcohol use presented with abdominal pain, emesis, and no bowel movements for 2 days. He had no history of surgical procedures, malignancies, diverticulitis, inflammatory bowel disease, traveling abroad, parasitic infections, tuberculosis exposure, or hospital admissions for abdominal pain. He reported experiencing no flushing, diarrhea, or cardiac symptoms. His medical history included hypertension, depression, and osteoarthritis. His vital signs were within normal limits.
A physical examination revealed a distended abdomen with mild tenderness. He had no inguinal or ventral hernias. He also had no abnormal skin lesions. A rectal examination did not reveal any masses or blood. His laboratory values were normal. X-ray and computed tomography (CT) scan revealed dilated loops of proximal small bowel, mild wall thickening in a segment of the midileum, and narrowing of the distal small bowel suggestive of a partial small bowel obstruction (Figure 1). A 1-cm nonspecific omental nodule also was seen on the CT scan, but no enlarged lymph nodes or mesenteric calcifications were seen. There was no thickening of the terminal ileum.
The patient underwent an exploratory laparotomy, which revealed no adhesions. In the midileum there was an area of thickened bowel with some nodularity associated with the thickness, but no discrete mass. In the mesentery there were multiple hard, white, calcified nodules, with the majority clustered near the thickened ileal segment. There also was a 1-cm hard, peritoneal mass on the anterior abdominal wall. The segment of thickened ileum, the adjacent mesentery, and the peritoneal nodule were resected.
Pathologic examination of the resected tissue showed immunohistochemical stains that were positive for CD79a, CD10, and BCL-2 and negative for CD23, CD5, and CD3. Nineteen mesenteric lymph nodes were negative for malignancy. The postoperative staging positron emission tomography (PET) scan did not reveal any fluorodeoxyglucose avid masses anywhere else, and bone marrow biopsy showed no infiltration.
- What is your diagnosis?
- How would you treat this patient?
Diagnosis
Based on the pathologic examination of the resected tissue and immunohistochemical stains, this patient was diagnosed with malignant non-Hodgkin B-cell lymphoma, follicular type, grade 1. PET scan and bone marrow biopsy revealed no other lesions, making this a primary lymphoma of the small intestine. The resected tissue showed negative margins and negative lymph nodes, indicating the full extent of the patient’s tumor was removed. He then underwent nasogastric tube decompression and IV fluid resuscitation. Two days later, he had a large bowel movement, and his abdominal pain resolved. He was provided the treatment options of observation only, radiation therapy, or rituximab treatment. Based on the high risk of enteritis following radiation therapy, the patient elected for observation only, with a repeat scan in 6 months. He also was counseled on alcohol and tobacco cessation. At the 6-month oncology follow-up, the patient showed no evidence of disease recurrence.
Discussion
Small bowel obstruction accounts for about 350,000 hospitalizations annually in the US.1 The incidence is equal in men and women and can present at any age.2,3 Patients typically present nonspecifically, with intermittent, colicky abdominal pain, nausea, vomiting, and constipation.2 A physical examination may reveal abdominal distention, rigidity, and hypoactive or absent bowel sounds.1 The 2 most common etiologies of small bowel obstruction are adhesions from prior abdominal surgery (65%) and incarcerated inguinal hernias (10%).1 However, in a patient presenting with a small bowel obstruction in a surgically naïve abdomen with no hernias, a more detailed history covering current malignancies, past hospital admissions for abdominal pains, pelvic inflammatory disease, diverticulitis, inflammatory bowel disease, and risks for parasite infection must be taken. The differential should include intraluminal causes, including small bowel malignancy, which accounts for 5% of small bowel obstructions,1 as well as extraluminal causes, including adhesions from diverticulitis, Meckel diverticulum, Ladd bands, and undiagnosed prior appendicitis.
To provide a tissue diagnosis and definitive treatment, surgical exploration was needed for this patient. Exploratory laparotomy revealed an area of thickened ileum and calcified nodules in its mesentery. Pathologic examination of the resected tissue revealed large lymphoid nodules in a follicular pattern with coarse chromatin (Figure 2). Taken together with the immunohistochemical stains, this was consistent with malignant B-cell non-Hodgkin lymphoma, follicular type, grade 1.
Small bowel malignancy accounts for > 5% of all gastrointestinal tumors.4 Of these, small bowel neuroendocrine tumors are the most common, followed by adenocarcinomas, lymphomas, and stromal tumors.4 Primary follicular lymphoma (PFL) is a B-cell non-Hodgkin lymphoma, and comprises between 3.8% and 11% of gastrointestinal lymphomas, commonly in the duodenum and terminal ileum.5
PFL typically occurs in middle-aged females and can be difficult to diagnose, as most patients are asymptomatic or present with unspecified abdominal pain. Many are diagnosed incidentally when endoscopy biopsies are performed for other reasons.4,5 Histologically, PFL is composed of a mixed population of small (centrocytes) and large (centroblasts) lymphoid cells, with higher proportions of centroblasts corresponding to a higher grade lymphoma.6 The classic immunophenotype of PFL shows coexpression of CD79a (or CD20), CD10, and BCL-2; however, in rare cases, low-grade PFL may stain negative for BCL-2 and have diminished staining for CD10 in interfollicular areas.7
PFL generally carries a favorable prognosis. Most patients achieving complete disease regression or stable disease following treatment and a low recurrence rate. Treatment can include surgical resection, radiation, rituximab therapy, chemotherapy, or observation.8 Patient also should be counseled in alcohol and tobacco cessation to reduce recurrence risk.
Other small bowel malignancies may present as small bowel obstructions as well. Neuroendocrine tumors and adenocarcinomas are both more common than small bowel lymphomas and can present as small bowel obstruction. However, neuroendocrine tumors are derived from serotonin-expressing enterochromaffin cells of the midgut and often present with classic carcinoid syndrome symptoms, including diarrhea, flushing, and right heart fibrosis, which the patient lacked.9 Immunohistology of small bowel adenocarcinoma often shows expression of MUC1 or MUC5AC with tumor markers CEA and CA 19-9.10
Primary intestinal melanoma, another small bowel malignancy, is extremely rare. More commonly, the etiology of intestinal melanoma is cutaneous melanoma that metastasizes to the gastrointestinal tract.11 This patient had no skin lesions to suggest metastatic melanoma. With intestinal melanoma, immunohistochemical evaluation may show S-100, the most sensitive marker for melanoma, or HMB-45, MART-1/Melan-A, tyrosinase, and MITF.12
Conclusion
This case is notable because it highlights the importance of examining the cause of small bowel obstruction in a surgically naïve abdomen, as exploration led to the discovery and curative treatment of a primary intestinal malignancy. It also underscores the nonspecific presentation that PFLs of the small intestine can have and the importance of understanding the different histopathology and immunohistochemical profiles of small bowel malignancies.
1. Rami Reddy SR, Cappell MS. A systematic review of the clinical presentation, diagnosis, and treatment of small bowel obstruction. Curr Gastroenterol Rep. 2017;19(6):28.
2. Smith DA, Nehring SM. Bowel obstruction. https://www.ncbi.nlm.nih.gov/books/NBK441975. Updated November 12, 2019. Accessed February 6, 2020.
3. Popoola D, Lou MA, Mansour AY, Sims EH. Small bowel obstruction: review of nine years of experience. J Natl Med Assoc. 1984;76(11):1089-1094.
4. Bilimoria KY, Bentrem DJ, Wayne JD, Ko CY, Bennett CL, Talamonti MS. Small bowel cancer in the United States: changes in epidemiology, treatment, and survival over the last 20 years. Ann Surg. 2009;249(1):63-71.
5. Freedman AS. Clinical presentation and diagnosis of primary gastrointestinal lymphomas. https://www.uptodate.com/contents/clinical-presentation-and-diagnosis-of-primary-gastrointestinal-lymphomas. Updated March 26, 2019. Accessed February 6, 2020.
6. Moy BT, Wilmot J, Ballesteros E, Forouhar F, Vaziri H. Primary follicular lymphoma of the gastrointestinal tract: casereport and review. J Gastrointest Cancer. 2016;47(3):255-263.
7. Choi SM, Betz BL, Perry AM. Follicular lymphoma diagnostic caveats and updates. Arch Pathol Lab Med. 2018;142(11):1330-1340.
8. Schmatz AI, Streubel B, Kretschmer-Chott E, et al. Primary follicular lymphoma of the duodenum is a distinct mucosal/submucosal variant of follicular lymphoma: a retrospective study of 63 cases. J Clin Oncol. 2011;29(11):1445-1451.
9. Grin A, Streutker CJ. Neuroendocrine tumors of the luminal gastrointestinal tract. Arch Pathol Lab Med. 2015;139(6):750-756.
10. Chang H-K, Yu E, Kim J, et al; Korean Small Intestinal Cancer Study Group. Adenocarcinoma of the small intestine: a multi-institutional study of 197 surgically resected cases. Hum Pathol. 2010;41(8):1087-1096.
11. Lens M, Bataille V, Krivokapic Z. Melanoma of the small intestine. Lancet Oncol. 2009;10(5):516-521.
12. Ohsie SJ, Sarantopoulos GP, Cochran AJ, Binder SW. Immunohistochemical characteristics of melanoma. J Cutan Pathol. 2008;35(5):433-444.
A 53-year-old male veteran with a history of heavy tobacco and alcohol use presented with abdominal pain, emesis, and no bowel movements for 2 days. He had no history of surgical procedures, malignancies, diverticulitis, inflammatory bowel disease, traveling abroad, parasitic infections, tuberculosis exposure, or hospital admissions for abdominal pain. He reported experiencing no flushing, diarrhea, or cardiac symptoms. His medical history included hypertension, depression, and osteoarthritis. His vital signs were within normal limits.
A physical examination revealed a distended abdomen with mild tenderness. He had no inguinal or ventral hernias. He also had no abnormal skin lesions. A rectal examination did not reveal any masses or blood. His laboratory values were normal. X-ray and computed tomography (CT) scan revealed dilated loops of proximal small bowel, mild wall thickening in a segment of the midileum, and narrowing of the distal small bowel suggestive of a partial small bowel obstruction (Figure 1). A 1-cm nonspecific omental nodule also was seen on the CT scan, but no enlarged lymph nodes or mesenteric calcifications were seen. There was no thickening of the terminal ileum.
The patient underwent an exploratory laparotomy, which revealed no adhesions. In the midileum there was an area of thickened bowel with some nodularity associated with the thickness, but no discrete mass. In the mesentery there were multiple hard, white, calcified nodules, with the majority clustered near the thickened ileal segment. There also was a 1-cm hard, peritoneal mass on the anterior abdominal wall. The segment of thickened ileum, the adjacent mesentery, and the peritoneal nodule were resected.
Pathologic examination of the resected tissue showed immunohistochemical stains that were positive for CD79a, CD10, and BCL-2 and negative for CD23, CD5, and CD3. Nineteen mesenteric lymph nodes were negative for malignancy. The postoperative staging positron emission tomography (PET) scan did not reveal any fluorodeoxyglucose avid masses anywhere else, and bone marrow biopsy showed no infiltration.
- What is your diagnosis?
- How would you treat this patient?
Diagnosis
Based on the pathologic examination of the resected tissue and immunohistochemical stains, this patient was diagnosed with malignant non-Hodgkin B-cell lymphoma, follicular type, grade 1. PET scan and bone marrow biopsy revealed no other lesions, making this a primary lymphoma of the small intestine. The resected tissue showed negative margins and negative lymph nodes, indicating the full extent of the patient’s tumor was removed. He then underwent nasogastric tube decompression and IV fluid resuscitation. Two days later, he had a large bowel movement, and his abdominal pain resolved. He was provided the treatment options of observation only, radiation therapy, or rituximab treatment. Based on the high risk of enteritis following radiation therapy, the patient elected for observation only, with a repeat scan in 6 months. He also was counseled on alcohol and tobacco cessation. At the 6-month oncology follow-up, the patient showed no evidence of disease recurrence.
Discussion
Small bowel obstruction accounts for about 350,000 hospitalizations annually in the US.1 The incidence is equal in men and women and can present at any age.2,3 Patients typically present nonspecifically, with intermittent, colicky abdominal pain, nausea, vomiting, and constipation.2 A physical examination may reveal abdominal distention, rigidity, and hypoactive or absent bowel sounds.1 The 2 most common etiologies of small bowel obstruction are adhesions from prior abdominal surgery (65%) and incarcerated inguinal hernias (10%).1 However, in a patient presenting with a small bowel obstruction in a surgically naïve abdomen with no hernias, a more detailed history covering current malignancies, past hospital admissions for abdominal pains, pelvic inflammatory disease, diverticulitis, inflammatory bowel disease, and risks for parasite infection must be taken. The differential should include intraluminal causes, including small bowel malignancy, which accounts for 5% of small bowel obstructions,1 as well as extraluminal causes, including adhesions from diverticulitis, Meckel diverticulum, Ladd bands, and undiagnosed prior appendicitis.
To provide a tissue diagnosis and definitive treatment, surgical exploration was needed for this patient. Exploratory laparotomy revealed an area of thickened ileum and calcified nodules in its mesentery. Pathologic examination of the resected tissue revealed large lymphoid nodules in a follicular pattern with coarse chromatin (Figure 2). Taken together with the immunohistochemical stains, this was consistent with malignant B-cell non-Hodgkin lymphoma, follicular type, grade 1.
Small bowel malignancy accounts for > 5% of all gastrointestinal tumors.4 Of these, small bowel neuroendocrine tumors are the most common, followed by adenocarcinomas, lymphomas, and stromal tumors.4 Primary follicular lymphoma (PFL) is a B-cell non-Hodgkin lymphoma, and comprises between 3.8% and 11% of gastrointestinal lymphomas, commonly in the duodenum and terminal ileum.5
PFL typically occurs in middle-aged females and can be difficult to diagnose, as most patients are asymptomatic or present with unspecified abdominal pain. Many are diagnosed incidentally when endoscopy biopsies are performed for other reasons.4,5 Histologically, PFL is composed of a mixed population of small (centrocytes) and large (centroblasts) lymphoid cells, with higher proportions of centroblasts corresponding to a higher grade lymphoma.6 The classic immunophenotype of PFL shows coexpression of CD79a (or CD20), CD10, and BCL-2; however, in rare cases, low-grade PFL may stain negative for BCL-2 and have diminished staining for CD10 in interfollicular areas.7
PFL generally carries a favorable prognosis. Most patients achieving complete disease regression or stable disease following treatment and a low recurrence rate. Treatment can include surgical resection, radiation, rituximab therapy, chemotherapy, or observation.8 Patient also should be counseled in alcohol and tobacco cessation to reduce recurrence risk.
Other small bowel malignancies may present as small bowel obstructions as well. Neuroendocrine tumors and adenocarcinomas are both more common than small bowel lymphomas and can present as small bowel obstruction. However, neuroendocrine tumors are derived from serotonin-expressing enterochromaffin cells of the midgut and often present with classic carcinoid syndrome symptoms, including diarrhea, flushing, and right heart fibrosis, which the patient lacked.9 Immunohistology of small bowel adenocarcinoma often shows expression of MUC1 or MUC5AC with tumor markers CEA and CA 19-9.10
Primary intestinal melanoma, another small bowel malignancy, is extremely rare. More commonly, the etiology of intestinal melanoma is cutaneous melanoma that metastasizes to the gastrointestinal tract.11 This patient had no skin lesions to suggest metastatic melanoma. With intestinal melanoma, immunohistochemical evaluation may show S-100, the most sensitive marker for melanoma, or HMB-45, MART-1/Melan-A, tyrosinase, and MITF.12
Conclusion
This case is notable because it highlights the importance of examining the cause of small bowel obstruction in a surgically naïve abdomen, as exploration led to the discovery and curative treatment of a primary intestinal malignancy. It also underscores the nonspecific presentation that PFLs of the small intestine can have and the importance of understanding the different histopathology and immunohistochemical profiles of small bowel malignancies.
A 53-year-old male veteran with a history of heavy tobacco and alcohol use presented with abdominal pain, emesis, and no bowel movements for 2 days. He had no history of surgical procedures, malignancies, diverticulitis, inflammatory bowel disease, traveling abroad, parasitic infections, tuberculosis exposure, or hospital admissions for abdominal pain. He reported experiencing no flushing, diarrhea, or cardiac symptoms. His medical history included hypertension, depression, and osteoarthritis. His vital signs were within normal limits.
A physical examination revealed a distended abdomen with mild tenderness. He had no inguinal or ventral hernias. He also had no abnormal skin lesions. A rectal examination did not reveal any masses or blood. His laboratory values were normal. X-ray and computed tomography (CT) scan revealed dilated loops of proximal small bowel, mild wall thickening in a segment of the midileum, and narrowing of the distal small bowel suggestive of a partial small bowel obstruction (Figure 1). A 1-cm nonspecific omental nodule also was seen on the CT scan, but no enlarged lymph nodes or mesenteric calcifications were seen. There was no thickening of the terminal ileum.
The patient underwent an exploratory laparotomy, which revealed no adhesions. In the midileum there was an area of thickened bowel with some nodularity associated with the thickness, but no discrete mass. In the mesentery there were multiple hard, white, calcified nodules, with the majority clustered near the thickened ileal segment. There also was a 1-cm hard, peritoneal mass on the anterior abdominal wall. The segment of thickened ileum, the adjacent mesentery, and the peritoneal nodule were resected.
Pathologic examination of the resected tissue showed immunohistochemical stains that were positive for CD79a, CD10, and BCL-2 and negative for CD23, CD5, and CD3. Nineteen mesenteric lymph nodes were negative for malignancy. The postoperative staging positron emission tomography (PET) scan did not reveal any fluorodeoxyglucose avid masses anywhere else, and bone marrow biopsy showed no infiltration.
- What is your diagnosis?
- How would you treat this patient?
Diagnosis
Based on the pathologic examination of the resected tissue and immunohistochemical stains, this patient was diagnosed with malignant non-Hodgkin B-cell lymphoma, follicular type, grade 1. PET scan and bone marrow biopsy revealed no other lesions, making this a primary lymphoma of the small intestine. The resected tissue showed negative margins and negative lymph nodes, indicating the full extent of the patient’s tumor was removed. He then underwent nasogastric tube decompression and IV fluid resuscitation. Two days later, he had a large bowel movement, and his abdominal pain resolved. He was provided the treatment options of observation only, radiation therapy, or rituximab treatment. Based on the high risk of enteritis following radiation therapy, the patient elected for observation only, with a repeat scan in 6 months. He also was counseled on alcohol and tobacco cessation. At the 6-month oncology follow-up, the patient showed no evidence of disease recurrence.
Discussion
Small bowel obstruction accounts for about 350,000 hospitalizations annually in the US.1 The incidence is equal in men and women and can present at any age.2,3 Patients typically present nonspecifically, with intermittent, colicky abdominal pain, nausea, vomiting, and constipation.2 A physical examination may reveal abdominal distention, rigidity, and hypoactive or absent bowel sounds.1 The 2 most common etiologies of small bowel obstruction are adhesions from prior abdominal surgery (65%) and incarcerated inguinal hernias (10%).1 However, in a patient presenting with a small bowel obstruction in a surgically naïve abdomen with no hernias, a more detailed history covering current malignancies, past hospital admissions for abdominal pains, pelvic inflammatory disease, diverticulitis, inflammatory bowel disease, and risks for parasite infection must be taken. The differential should include intraluminal causes, including small bowel malignancy, which accounts for 5% of small bowel obstructions,1 as well as extraluminal causes, including adhesions from diverticulitis, Meckel diverticulum, Ladd bands, and undiagnosed prior appendicitis.
To provide a tissue diagnosis and definitive treatment, surgical exploration was needed for this patient. Exploratory laparotomy revealed an area of thickened ileum and calcified nodules in its mesentery. Pathologic examination of the resected tissue revealed large lymphoid nodules in a follicular pattern with coarse chromatin (Figure 2). Taken together with the immunohistochemical stains, this was consistent with malignant B-cell non-Hodgkin lymphoma, follicular type, grade 1.
Small bowel malignancy accounts for > 5% of all gastrointestinal tumors.4 Of these, small bowel neuroendocrine tumors are the most common, followed by adenocarcinomas, lymphomas, and stromal tumors.4 Primary follicular lymphoma (PFL) is a B-cell non-Hodgkin lymphoma, and comprises between 3.8% and 11% of gastrointestinal lymphomas, commonly in the duodenum and terminal ileum.5
PFL typically occurs in middle-aged females and can be difficult to diagnose, as most patients are asymptomatic or present with unspecified abdominal pain. Many are diagnosed incidentally when endoscopy biopsies are performed for other reasons.4,5 Histologically, PFL is composed of a mixed population of small (centrocytes) and large (centroblasts) lymphoid cells, with higher proportions of centroblasts corresponding to a higher grade lymphoma.6 The classic immunophenotype of PFL shows coexpression of CD79a (or CD20), CD10, and BCL-2; however, in rare cases, low-grade PFL may stain negative for BCL-2 and have diminished staining for CD10 in interfollicular areas.7
PFL generally carries a favorable prognosis. Most patients achieving complete disease regression or stable disease following treatment and a low recurrence rate. Treatment can include surgical resection, radiation, rituximab therapy, chemotherapy, or observation.8 Patient also should be counseled in alcohol and tobacco cessation to reduce recurrence risk.
Other small bowel malignancies may present as small bowel obstructions as well. Neuroendocrine tumors and adenocarcinomas are both more common than small bowel lymphomas and can present as small bowel obstruction. However, neuroendocrine tumors are derived from serotonin-expressing enterochromaffin cells of the midgut and often present with classic carcinoid syndrome symptoms, including diarrhea, flushing, and right heart fibrosis, which the patient lacked.9 Immunohistology of small bowel adenocarcinoma often shows expression of MUC1 or MUC5AC with tumor markers CEA and CA 19-9.10
Primary intestinal melanoma, another small bowel malignancy, is extremely rare. More commonly, the etiology of intestinal melanoma is cutaneous melanoma that metastasizes to the gastrointestinal tract.11 This patient had no skin lesions to suggest metastatic melanoma. With intestinal melanoma, immunohistochemical evaluation may show S-100, the most sensitive marker for melanoma, or HMB-45, MART-1/Melan-A, tyrosinase, and MITF.12
Conclusion
This case is notable because it highlights the importance of examining the cause of small bowel obstruction in a surgically naïve abdomen, as exploration led to the discovery and curative treatment of a primary intestinal malignancy. It also underscores the nonspecific presentation that PFLs of the small intestine can have and the importance of understanding the different histopathology and immunohistochemical profiles of small bowel malignancies.
1. Rami Reddy SR, Cappell MS. A systematic review of the clinical presentation, diagnosis, and treatment of small bowel obstruction. Curr Gastroenterol Rep. 2017;19(6):28.
2. Smith DA, Nehring SM. Bowel obstruction. https://www.ncbi.nlm.nih.gov/books/NBK441975. Updated November 12, 2019. Accessed February 6, 2020.
3. Popoola D, Lou MA, Mansour AY, Sims EH. Small bowel obstruction: review of nine years of experience. J Natl Med Assoc. 1984;76(11):1089-1094.
4. Bilimoria KY, Bentrem DJ, Wayne JD, Ko CY, Bennett CL, Talamonti MS. Small bowel cancer in the United States: changes in epidemiology, treatment, and survival over the last 20 years. Ann Surg. 2009;249(1):63-71.
5. Freedman AS. Clinical presentation and diagnosis of primary gastrointestinal lymphomas. https://www.uptodate.com/contents/clinical-presentation-and-diagnosis-of-primary-gastrointestinal-lymphomas. Updated March 26, 2019. Accessed February 6, 2020.
6. Moy BT, Wilmot J, Ballesteros E, Forouhar F, Vaziri H. Primary follicular lymphoma of the gastrointestinal tract: casereport and review. J Gastrointest Cancer. 2016;47(3):255-263.
7. Choi SM, Betz BL, Perry AM. Follicular lymphoma diagnostic caveats and updates. Arch Pathol Lab Med. 2018;142(11):1330-1340.
8. Schmatz AI, Streubel B, Kretschmer-Chott E, et al. Primary follicular lymphoma of the duodenum is a distinct mucosal/submucosal variant of follicular lymphoma: a retrospective study of 63 cases. J Clin Oncol. 2011;29(11):1445-1451.
9. Grin A, Streutker CJ. Neuroendocrine tumors of the luminal gastrointestinal tract. Arch Pathol Lab Med. 2015;139(6):750-756.
10. Chang H-K, Yu E, Kim J, et al; Korean Small Intestinal Cancer Study Group. Adenocarcinoma of the small intestine: a multi-institutional study of 197 surgically resected cases. Hum Pathol. 2010;41(8):1087-1096.
11. Lens M, Bataille V, Krivokapic Z. Melanoma of the small intestine. Lancet Oncol. 2009;10(5):516-521.
12. Ohsie SJ, Sarantopoulos GP, Cochran AJ, Binder SW. Immunohistochemical characteristics of melanoma. J Cutan Pathol. 2008;35(5):433-444.
1. Rami Reddy SR, Cappell MS. A systematic review of the clinical presentation, diagnosis, and treatment of small bowel obstruction. Curr Gastroenterol Rep. 2017;19(6):28.
2. Smith DA, Nehring SM. Bowel obstruction. https://www.ncbi.nlm.nih.gov/books/NBK441975. Updated November 12, 2019. Accessed February 6, 2020.
3. Popoola D, Lou MA, Mansour AY, Sims EH. Small bowel obstruction: review of nine years of experience. J Natl Med Assoc. 1984;76(11):1089-1094.
4. Bilimoria KY, Bentrem DJ, Wayne JD, Ko CY, Bennett CL, Talamonti MS. Small bowel cancer in the United States: changes in epidemiology, treatment, and survival over the last 20 years. Ann Surg. 2009;249(1):63-71.
5. Freedman AS. Clinical presentation and diagnosis of primary gastrointestinal lymphomas. https://www.uptodate.com/contents/clinical-presentation-and-diagnosis-of-primary-gastrointestinal-lymphomas. Updated March 26, 2019. Accessed February 6, 2020.
6. Moy BT, Wilmot J, Ballesteros E, Forouhar F, Vaziri H. Primary follicular lymphoma of the gastrointestinal tract: casereport and review. J Gastrointest Cancer. 2016;47(3):255-263.
7. Choi SM, Betz BL, Perry AM. Follicular lymphoma diagnostic caveats and updates. Arch Pathol Lab Med. 2018;142(11):1330-1340.
8. Schmatz AI, Streubel B, Kretschmer-Chott E, et al. Primary follicular lymphoma of the duodenum is a distinct mucosal/submucosal variant of follicular lymphoma: a retrospective study of 63 cases. J Clin Oncol. 2011;29(11):1445-1451.
9. Grin A, Streutker CJ. Neuroendocrine tumors of the luminal gastrointestinal tract. Arch Pathol Lab Med. 2015;139(6):750-756.
10. Chang H-K, Yu E, Kim J, et al; Korean Small Intestinal Cancer Study Group. Adenocarcinoma of the small intestine: a multi-institutional study of 197 surgically resected cases. Hum Pathol. 2010;41(8):1087-1096.
11. Lens M, Bataille V, Krivokapic Z. Melanoma of the small intestine. Lancet Oncol. 2009;10(5):516-521.
12. Ohsie SJ, Sarantopoulos GP, Cochran AJ, Binder SW. Immunohistochemical characteristics of melanoma. J Cutan Pathol. 2008;35(5):433-444.