Therapeutic Value of Sentinel Lymph Node Biopsy in Patients With Melanoma: A Randomized Clinical Trial.

Importance: Sentinel lymph node (SLN) biopsy is a standard staging procedure for cutaneous melanoma. Regional disease control is a clinically important therapeutic goal of surgical intervention, including nodal surgery. Objective: To determine how frequently SLN biopsy without completion lymph node dissection (CLND) results in long-term regional nodal disease control in patients with SLN metastases. Design, Setting, and Participants: The second Multicenter Selective Lymphadenectomy Trial (MSLT-II), a prospective multicenter randomized clinical trial, randomized participants with SLN metastases to either CLND or nodal observation. The current analysis examines observation patients with regard to regional nodal recurrence. Trial patients were aged 18 to 75 years with melanoma metastatic to SLN(s). Data were collected from December 2004 to April 2019, and data were analyzed from July 2020 to January 2022. Interventions: Nodal observation with ultrasonography rather than CLND. Main Outcomes and Measures: In-basin nodal recurrence. Results: Of 823 included patients, 479 (58.2%) were male, and the mean (SD) age was 52.8 (13.8) years. Among 855 observed basins, at 10 years, 80.2% (actuarial; 95% CI, 77-83) of basins were free of nodal recurrence. By univariable analysis, freedom from regional nodal recurrence was associated with age younger than 50 years (hazard ratio [HR], 0.49; 95% CI, 0.34-0.70; P < .001), nonulcerated melanoma (HR, 0.36; 95% CI, 0.36-0.49; P < .001), thinner primary melanoma (less than 1.5 mm; HR, 0.46; 95% CI, 0.27-0.78; P = .004), axillary basin (HR, 0.61; 95% CI, 0.44-0.86; P = .005), fewer positive SLNs (1 vs 3 or more; HR, 0.32; 95% CI, 0.14-0.75; P = .008), and SLN tumor burden (measured by diameter less than 1 mm [HR, 0.39; 95% CI, 0.26-0.60; P = .001] or less than 5% area [HR, 0.36; 95% CI, 0.24-0.54; P < .001]). By multivariable analysis, younger age (HR, 0.57; 95% CI, 0.39-0.84; P = .004), thinner primary melanoma (HR, 0.40; 95% CI, 0.22-0.70; P = .002), axillary basin (HR, 0.55; 95% CI, 0.31-0.96; P = .03), SLN metastasis diameter less than 1 mm (HR, 0.52; 95% CI, 0.33-0.81; P = .007), and area less than 5% (HR, 0.58; 95% CI, 0.38-0.88; P = .01) were associated with basin control. When looking at the identified risk factors of age (50 years or older), ulceration, Breslow thickness greater than 3.5 mm, nonaxillary basin, and tumor burden of maximum diameter of 1 mm or greater and/or metastasis area of 5% or greater and excluding missing value cases, basin disease-free rates at 5 years were 96% (95% CI, 88-100) for patients with 0 risk factors, 89% (95% CI, 82-96) for 1 risk factor, 86% (95% CI, 80-93) for 2 risk factors, 80% (95% CI, 71-89) for 3 risk factors, 61% (95% CI, 48-74) for 4 risk factors, and 54% (95% CI, 36-72) for 5 or 6 risk factors. Conclusions and Relevance: This randomized clinical trial was the largest prospective evaluation of long-term regional basin control in patients with melanoma who had nodal observation after removal of a positive SLN. SLN biopsy without CLND cleared disease in the affected nodal basin in most patients, even those with multiple risk factors for in-basin recurrence. In addition to its well-validated value in staging, SLN biopsy may also be regarded as therapeutic in some patients. Trial Registration: ClinicalTrials.gov Identifier: NCT00297895.

Peritoneal MRI in patients undergoing cytoreductive surgery and HIPEC: History, clinical applications, and implementation.

MR imaging provides considerable advantages in the evaluation of patients with peritoneal metastases. A standardized peritoneal MRI protocol, including diffusion-weighted and gadolinium-enhanced sequences, allows an efficient exploration of small peritoneal tumors that are often missed on other imaging tests. In experienced hands, a dedicated reading allows producing a quantitative and qualitative evaluation of lesional localization to better assist surgeons in the selection of candidates for curative surgery by evaluating the possibility of complete resection, and to plan the surgical procedure. Based on a close collaboration between oncologic surgeon and radiologist, MRI provides a powerful tool for accurate preoperative imaging in patients being considered for curative surgery but also in their surveillance to detect an early recurrence.

Detection of Mesenteric Tumor Using Dynamic Contrast Enhanced MRI.

PURPOSE: This study was designed to evaluate the use of a novel imaging technique, dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), for detecting mesenteric peritoneal metastases. METHODS: Thirty-four patients underwent preoperative conventional MRI, including T1, T2, diffusion-weighted (DWI), and delayed gadolinium MRI, as well as DCE MRI. DCE MRI involved imaging the peritoneal cavity every 9 s for 6 min. DCE images were processed to generate parametric maps of tumor vascularity. Two oncologic surgeons and a radiologist reviewed conventional MRI for all tumor and then later reviewed the conventional MRI plus the DCE parametric maps. Images were reviewed for tumor of the parietal peritoneum, porta hepatis, bowel serosa, upper small bowel mesentery, lower small bowel mesentery, and pelvis. Conventional MRI and DCE + MRI findings were compared to operative and histopathologic reports for tumor detection. PCI scores were calculated for surgery, MRI, and DCE. RESULTS: Upper mesenteric tumor was present in 21 patients. DCE images showed a sensitivity of 100%, specificity of 92%, and accuracy of 97% compared with conventional MRI sensitivity of 24%, specificity of 93%, and accuracy of 50% (p = 0.006). Lower mesenteric tumor was present in 22 patients. DCE images showed a sensitivity of 100%, specificity of 92%, and accuracy of 97% compared with conventional MRI sensitivity of 45%, specificity of 92%, and accuracy of 62% (p = 0.008). The mean surgical PCI for all 34 patients was 23.4 compared with MRI 20.0 (p = 0.003) and DCE MRI 24.1 (p = 0.26). The addition of the DCE images improved the accuracy of total PCI by > 10% in 16 (0.46) patients. For PCI regions 9-12, the mean surgical PCI was 6.0 compared with MRI 4.8 (p = 0.08) and DCE 6.6 (p = 0.02). The addition of DCE images improved the accuracy of the regional PCI > 10% in 15 (0.43) patients. CONCLUSIONS: DCE MRI provides a novel contrast tool that improves detection of mesenteric tumor. Depicting small-volume mesenteric tumor is better on DCE MRI compared with conventional MRI.

Does Primary Tumor Side Matter in Patients with Metastatic Colon Cancer Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy?

BACKGROUND: Primary tumor location has been shown to be prognostic of overall survival (OS) in patients with both locally advanced and metastatic colorectal cancer. The impact of sidedness on prognosis has not been evaluated in the setting of peritoneal-only metastases treated with cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). METHODS: A retrospective review of prospectively maintained databases of patients with peritoneal surface malignancy undergoing CRS/HIPEC from three high-volume centers was performed. RESULTS: A total of 115 patients with metastatic colon cancer to the peritoneum who underwent CRS/HIPEC with mitomycin C were identified. Fifty-one patients (45%) had left-sided primary tumors, and 64 (55%) had right-sided primary tumors. Patients with right-sided tumors were more likely to be older (median age 56 vs. 49 years, p = 0.007) and to have signet ring cell histology (17% vs. 4%, p = 0.026). Patients with right-sided tumors had median disease-free survival (DFS) and OS of 14 months (95% confidence interval [CI] 10.5-17.5) and 36 months (95% CI 27.4-44.6), respectively, versus 16 months (95% CI 11.0-21.0) and 69 months (95% CI 24.3-113.7) for those patients with left-sided tumors. On multivariate analysis, primary tumor side was an independent predictor of both DFS and OS. CONCLUSIONS: In this study, there was a dramatic, clinically significant difference in OS between patients with right- and left-sided tumors, and primary tumor side was an independent predictor of DFS and OS. Primary tumor side should be considered in patient selection for CRS with or without HIPEC.

Imaging for Peritoneal Metastases.

MRI provides considerable advantages for imaging of patients with peritoneal tumor. Its inherently superior contrast resolution compared with computed tomography allows MRI to more accurately depict small peritoneal tumors that are often missed on other imaging tests. Combining different contrast mechanisms, including diffusion-weighted MRI and gadolinium-enhanced MRI, provides a powerful tool for preoperative and surveillance imaging in patients being considered for cytoreductive surgery and heated intraperitoneal chemotherapy.

Comparison of MRI and CT for predicting the Peritoneal Cancer Index (PCI) preoperatively in patients being considered for cytoreductive surgical procedures.

PURPOSE: To compare the accuracy of MRI and CT for predicting the Peritoneal Cancer Index (PCI) preoperatively compared with the PCI tabulated at surgery. METHODS: Twenty-two patients underwent preoperative MRI and CT scanning followed by cytoreductive surgery for appendiceal (n = 17) and ovarian (n = 5) cancer. MR and CT examinations were retrospectively reviewed to determine the PCI. The results of these scores were compared with PCI tabulated at surgery. Patients were categorized as small volume tumor (PCI 0-9), moderate volume (PCI 10-20), and large volume (PCI > 20). Respective anatomic site scores for MRI and CT were compared with surgical findings. RESULTS: Compared with surgical PCI, MRI correctly categorized tumor volume in 20 (0.91) of 22 patients, including 3 of 4 patients with small volume tumor, 2 of 2 patients with moderate volume tumor, and 15 of 16 patients with large volume tumor. CT correctly categorized tumor volume in 11 of 22 (0.50) patients, including 2 of 4 patients with small-volume tumor, 2 of 2 patients with moderate volume tumor, and 7 of 16 patients with large-volume tumor. In 19 of 22 patients, CT underestimated the volume of tumor found at surgery. For all patients, the median PCI score at surgery was 33 compared with 36 for MRI and 15 for CT. Surgery confirmed 222 sites of tumor. MRI demonstrated per site sensitivity of 0.95, specificity 0.70, and accuracy 0.88. CT showed a corresponding per site sensitivity 0.55, specificity 0.86, and accuracy 0.63. CONCLUSIONS: MRI more accurately predicts PCI preoperatively in patients undergoing evaluation for cytoreductive surgery.

Surveillance MR imaging is superior to serum tumor markers for detecting early tumor recurrence in patients with appendiceal cancer treated with surgical cytoreduction and HIPEC.

BACKGROUND: The purpose of this study was to determine if MRI surveillance is better than serum tumor makers in detecting early recurrence in patients with mucinous appendiceal neoplasm. MATERIALS AND METHODS: A total of 50 patients with appendiceal neoplasm (DPAM 11, PMCA 39) underwent abdominal and pelvic MRI prior to surgical cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC). Patients then entered follow-up surveillance with serial MRI every 6 months and serial laboratory studies including CA 125, CEA, and CA19-9. Written reports for surveillance MRI exams were reviewed for tumor recurrence and compared with results of serial laboratory tests. Proof of tumor recurrence was by a consensus of surgery and histopathology, as well as clinical and imaging findings on serial examinations. RESULTS: During surveillance tumor recurrence was documented in 30 patients (60 %) with median time to recurrence of 13 months (range 3-56 months). MRI detected recurrent tumor in 28 patients, including 11 patients with normal laboratory values (sensitivity 0.93, specificity 0.95, accuracy 0.94, PPV 0.97, and NPV 0.90). Serial laboratory values showed tumor recurrence in 14 patients (sensitivity 0.48, specificity 1.00, accuracy 0.69, PPV 1.0, and NPV 0.57). Median survival was 50 months for 11 patients with earlier MRI detection of recurrence vs 33 months for the other 19 patients with recurrence. CONCLUSIONS: Following cytoreductive surgery and HIPEC MRI detects tumor recurrence earlier and with greater accuracy than serial tumor markers alone.

Combined diffusion-weighted and gadolinium-enhanced MRI can accurately predict the peritoneal cancer index preoperatively in patients being considered for cytoreductive surgical procedures.

PURPOSE: To determine whether abdominal and pelvic magnetic resonance imaging (MRI) with diffusion-weighted and dynamic gadolinium-enhanced imaging can be used to accurately calculate the peritoneal cancer index (PCI) before surgery compared to the PCI tabulated at surgery. METHODS: Thirty-three patients underwent preoperative MRI followed by cytoreductive surgery for primary tumors of the appendix (n = 25), ovary (n = 5), colon (n = 2), and mesothelioma (n = 1). MRIs were retrospectively reviewed to determine the MRI PCI. These scores were then compared to PCI tabulated at surgery. Patients were categorized as having small-volume tumors (PCI 0­9), moderate-volume tumors (PCI 10­20), and large-volume tumors (PCI > 20). The respective anatomic site scores for both MRI and surgery were compared. RESULTS: There was no significant difference between the MRI PCI and surgical PCI for the 33 patients (P = 0.12). MRI correctly predicted the PCI category in 29 (0.88) of 33 patients. Compared to surgical findings, MRI correctly predicted small-volume tumor in 6 of 7 patients, moderate-volume tumor in 3 of 4 patients, and large-volume tumor in 20 of 22 patients. MRI and surgical PCI scores were identical in 8 patients (24%). A difference of <5 was noted in 16 patients (49%) and of 5­10 in 9 patients (27%). Compared to surgical-site findings, MRI depicted 258 truly positive sites of peritoneal tumor, 35 falsely negative sites, 35 falsely positive sites, and 101 truly negative sites, with a corresponding sensitivity of 0.88, specificity of 0.74, and accuracy of 0.84. CONCLUSIONS: Combined diffusion-weighted and gadolinium-enhanced peritoneal MRI accurately predicts the PCI before surgery in patients undergoing evaluation for cytoreductive surgery.

Diffusion-weighted MRI of peritoneal tumors: comparison with conventional MRI and surgical and histopathologic findings--a feasibility study.

OBJECTIVE: The purpose of our study was to evaluate the utility of single-shot spin-echo echo-planar diffusion-weighted imaging (DWI) using a b value of 400-500 s/mm(2) for depicting peritoneal tumors. MATERIALS AND METHODS: Thirty-four consecutive oncology patients underwent preoperative abdominal and pelvic MRI for tumor staging. MRI included breath-hold DWI with a b value of 400-500 s/mm(2), T1-weighted spoiled gradient-echo, T2-weighted fast spin-echo, and 0- and 5-minute delayed gadolinium-enhanced imaging. At three separate sessions, two observers independently reviewed images for peritoneal tumors at 16 anatomic sites. First DWI alone was reviewed, followed by conventional MRI alone, and then conventional MRI, including DWI, was reviewed. Results of laparotomy and histopathologic evaluation were compared with MRI results. Sensitivity, specificity, and accuracy were calculated for DWI, conventional MRI, and combined DWI and conventional MRI for peritoneal tumor depiction. RESULTS: Two-hundred fifty-five sites of peritoneal tumor were proven by surgical and histopathologic findings. The combination of DWI and conventional MRI was most sensitive and accurate for peritoneal tumors, depicting 230 and 214 tumor sites for the two observers (sensitivity, 0.90, 0.84; and accuracy, 0.91, 0.88) compared with DWI alone, which depicted 182 and 182 tumor sites with sensitivity (0.71, 0.71; and accuracy, 0.81, 0.81), and conventional MRI alone, which depicted 185 and 132 tumor sites (sensitivity, 0.73, 0.52; and accuracy, 0.81, 0.72). Peritoneal tumor showed restricted diffusion on DWI and ascites was of low signal intensity, increasing tumor conspicuity. CONCLUSION: Adding DWI to routine MRI improves the sensitivity and specificity for depicting peritoneal metastases. Breath-hold DWI is now routinely used in all oncology patients referred for abdominal MRI at our institution.

Mucinous appendiceal neoplasms: preoperative MR staging and classification compared with surgical and histopathologic findings.

OBJECTIVE: The objective of our study was to determine the accuracy of MRI in the preoperative staging and classification of mucinous appendiceal neoplasms and to describe the MRI features that are useful for selecting patients for surgical resection. MATERIALS AND METHODS: Twenty-two patients underwent preoperative MRI including T1-weighted, T2-weighted, immediate gadolinium-enhanced, and delayed gadolinium-enhanced imaging. Two observers reviewed the images for peritoneal tumor at 13 sites, tumor size and distribution, and degree of tumor enhancement. Peritoneal tumor sites were recorded at surgery. Cytoreduction was categorized as complete or suboptimal. Surgical specimens were classified as disseminated peritoneal adenomucinosis tumors, intermediate-grade tumors, or peritoneal mucinous carcinomatosis tumors. RESULTS: Surgery confirmed 232 tumor sites. Delayed gadolinium-enhanced MRI was the most accurate of the MR techniques, with a sensitivity, specificity, and accuracy of 89%, 87%, and 89%, respectively, for observer 1 and 82%, 87%, and 83% for observer 2 (p < 0.001). Surgical cytoreduction was complete in 14 patients and suboptimal in eight. MRI findings predicting suboptimal cytoreduction included a large (> 5 cm) mesenteric mass, which was present in 75% of the patients in the suboptimal cytoreduction group and 0% of those in the complete cytoreduction group; diffuse mesenteric tumor (88% and 0%, respectively); tumor encasement of mesenteric vessels (88% and 0%); or diffuse small-bowel serosal tumor (75% and 0%). Histopathology results showed six disseminated peritoneal adenomucinosis tumors, four intermediate tumors, and 11 peritoneal mucinous carcinomatosis tumors. The specimens for the remaining patient were not available for histopathologic analysis. Qualitatively, the 11 peritoneal mucinous carcinomatosis tumors showed greater enhancement than the liver, whereas six disseminated peritoneal adenomucinosis and the four intermediate tumors showed less enhancement than the liver. Quantitatively, the mean tumor-to-liver contrast for disseminated peritoneal adenomucinosis and intermediate tumors was 0.67 compared with 1.53 for peritoneal mucinous carcinomatosis tumors (p < 0.0001). CONCLUSION: Of the MR techniques evaluated, delayed gadolinium-enhanced MRI was the most accurate for the staging and classification of mucinous appendiceal neoplasms and provided prognostic information useful for patient selection.

Anterior exposure of the spine for removal of lumbar interbody devices and implants.

STUDY DESIGN: A retrospective review of a consecutive series of 14 patients operated on between March 1998 and April 2005. OBJECTIVES: To report on patients having undergone revision lumbar surgery anteriorly to remove interbody devices placed anteriorly or posteriorly and to determine the incidence of associated complications. SUMMARY OF BACKGROUND DATA: The popularity of interbody lumbar surgery has grown in recent years. Consequently, the number of anterior revision procedures has increased. The risks associated with anterior approach for revision procedures and interbody device removal, in particular, have not been reported. METHODS: The results of 13 consecutive patients who had removal of interbody devices through an anterior approach and 1 patient with removal of anterior fixation (7 males, 7 females; mean age 43 years) were reviewed. The procedure during which the original implant was placed was a posterior lumbar interbody fusion in 4, transforaminal lumbar interbody fusion in 5, and anterior lumbar interbody fusion in 5 patients. Four attending spine surgeons performed the procedures with the assistance of 4 experienced access surgeons. RESULTS: Ten of 14 (71%) patients had complications associated with anterior exposure of revision surgery. Vascular injury is the most common complication (57%). Vascular complications occurred in 100% (4/4) of the revisions of previous posterior lumbar interbody fusions and 80% (4/5) of previous anterior lumbar interbody fusions. The complication rate at L4-5 and L5-S1 was 89% and 40%, respectively. There was 1 postoperative mortality. CONCLUSIONS: Anterior removal of lumbar interbody devices placed anteriorly or posteriorly has a high incidence of complication. Average blood loss and hospital stay are increased with revision anterior surgery. The vascular complication rate is 2-fold higher at L4-L5 level compared to L5-S1.

Combined thigh flap for closure of massive trunk defect.

A massive trunk defect resulting from resection of recurrent sarcoma was reconstructed with a combined free flap incorporating medial, anterior, and lateral thigh tissues. This flap included the tensor fasciae latae, lateral thigh perforator, and rectus femoris, all based on the lateral femoral circumflex pedicle. A saphenous vein conduit enabled this flap to replace resected tissues at the lower thorax. Combining the three different commonly used thigh flaps on a single large pedicle enabled transfer of a 47.5 x 33.5-cm mega-flap.

Treated ovarian cancer: MR imaging, laparotomy reassessment, and serum CA-125 values compared with clinical outcome at 1 year.

PURPOSE: To compare retrospectively the use of magnetic resonance (MR) imaging, laparotomy reassessment, and serum CA-125 values in predicting the presence of residual tumor in women who have been treated for ovarian cancer. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was waived. The study was compliant with the Health Insurance Portability and Accountability Act. Seventy-six women (mean age, 59 years) with treated ovarian cancer underwent preoperative MR imaging of the abdomen and pelvis with intravenous gadolinium-based and intraluminal barium contrast material. MR findings were compared with surgical and histopathologic findings, serial and static serum CA-125 values, and clinical follow-up results. Tumor absence was proved with normal surgical results and by following up patients for at least 1 year, with no evidence of residual tumor at serial CA-125 analysis or subsequent laparotomy. McNemar test for correlated proportions was used for statistical analysis. RESULTS: Sixty-eight women had residual tumor proved at laparotomy and biopsy or at clinical follow-up. Eight patients had no evidence of residual tumor. Gadolinium-enhanced MR imaging depicted residual tumor in 61 patients (sensitivity, 90%; specificity, 88%; accuracy, 89%) compared with laparotomy, which demonstrated residual tumor in 60 patients (sensitivity, 88%; specificity, 100%; accuracy, 89%) and CA-125 values, which demonstrated residual tumor in 44 patients (sensitivity, 65%; specificity, 88%; accuracy, 67%) (P < .01). The positive predictive values for MR imaging, laparotomy, and serum CA-125 values were 98%, 100%, and 98%, respectively, whereas the corresponding negative predictive values were 50%, 50%, and 23%, respectively. In 14 patients, there was a discrepancy between the results of MR imaging and those of laparotomy. In seven patients, MR imaging depicted residual tumor that was not found at laparotomy but was proved at subsequent biopsy or clinical and imaging follow-up, with an increasing serum CA-125 level. In six patients, MR findings were normal, and subsequent laparotomy revealed small-volume residual tumor. Residual tumor was incorrectly predicted with MR imaging in one patient who had no surgical or clinical evidence of residual tumor for 1 year. CONCLUSION: Gadolinium-enhanced spoiled gradient-echo MR imaging depicts residual tumor in women with treated ovarian cancer, with an accuracy, positive predictive value, and negative predictive value that are comparable to those of laparotomy and superior to those of serum CA-125 values alone.

The rationale of perioperative intraperitoneal chemotherapy in the treatment of peritoneal surface malignancies.

In summary, the use of perioperative intraperitoneal chemotherapy is a rational and scientifically sound treatment option for patients with peritoneal carcinomatosis. By delivering chemotherapeutic agents directly into the peritoneal cavity in the perioperative period, after cytoreductive procedures resulting in minimal residual tumor load, the cytotoxicity, efficacy, and safety of these agents can be maximized. The use of this treatment strategy in the intraoperative or perioperative period ensures that the efficacy of the chemotherapeutic agents is not reduced by limitations of abdominal compartmentalization and scarring. Treating patients under hyperthermic conditions may confer an additional benefit. Although the use of perioperative chemotherapy or hyperthermic intraperitoneal chemotherapy is not yet part of the standard of care for the treatment of advanced abdominal malignancies, both basic science and clinical investigations have confirmed the validity of these regimens. Further clinical studies in a cooperative group setting are necessary to prove the efficacy of perioperative intraperitoneal chemotherapy in both the treatment and prevention of peritoneal surface malignancy.

Distinguishing benign from malignant bowel obstruction in patients with malignancy: findings at MR imaging.

PURPOSE: To retrospectively evaluate the features of benign versus malignant bowel obstruction on unenhanced and gadolinium-enhanced spoiled gradient-echo magnetic resonance (MR) images in patients with malignancy. MATERIALS AND METHODS: Forty-eight patients with malignancy and bowel obstruction underwent abdominal and pelvic MR imaging. Two blinded radiologists independently evaluated each study for dilated bowel, transition point, level of obstruction, obstructing mass, mural thickening and enhancement, and peritoneal disease. Benign obstruction was recorded if no mass was present and if mural thickening (when present) was segmental or diffuse. Malignant bowel obstruction was recorded if there was a mass, a disseminated abdominal tumor, or focal mural thickening. MR images were compared with surgical findings, follow-up imaging studies, and clinical outcome. chi2 test and Fisher exact test were used to assess the relationship between the MR features and benign versus malignant obstruction. RESULTS: Bowel obstruction had a benign cause in 19 patients and a malignant cause in 29 patients. Observer 1 correctly characterized benign bowel obstruction in 17 of 19 patients and malignant bowel obstruction in 27 of 29 patients. The sensitivity of observer 1 for characterizing malignant obstruction was 93%, specificity was 89%, and accuracy was 92%. Observer 2 correctly characterized benign bowel obstruction in 18 of 19 patients and malignant bowel obstruction in 26 of 29 patients. The sensitivity of observer 2 for characterizing malignant obstruction was 90%, specificity was 95%, and accuracy was 92%. Malignant bowel obstruction was present in 24 of 25 patients with an obstructing mass (P <.001). All 16 patients with focal mural thickening had malignant obstruction. Benign obstruction was present in four of five patients with diffuse mural thickening. Segmental mural thickening occurred in four patients with serosal metastases and in 11 patients with benign bowel obstruction. More extensive peritoneal thickening and enhancement correlated with malignant obstruction. CONCLUSION: In patients with malignancy who have symptoms indicative of bowel obstruction, gadolinium-enhanced MR imaging can help distinguish benign from malignant causes of bowel obstruction.

Secondary amyloidosis and gastrointestinal stromal tumors. A case report and discussion of pathogenesis.

A 69-year-old man presented with a malignant gastrointestinal stromal tumor associated with secondary amyloidosis. The tumor had classic features of a malignant gastrointestinal stromal tumor with interlacing fascicles and whorls of spindled cells, numerous and conspicuous mitotic figures, and extensive coagulative necrosis. The cells stained diffusely for CD117 (c-Kit), confirming the diagnosis of gastrointestinal stromal tumor. The spleen, 1 adrenal gland, and part of the pancreas were removed en block with the stomach. By microscopy, the spleen and adrenal gland were partially replaced with amyloid deposits confirmed by Congo red staining, electron microscopy, and immunohistochemistry. In contrast, neither the tumor nor the surrounding vasculature showed amyloid deposition. To our knowledge, this represents only the second case of systemic amyloidosis associated with a gastrointestinal stromal tumor. This case is unique in that extensive, diffuse amyloid deposits were observed in the spleen, adrenal gland, and liver.