Colorectal mesenchymal tumor: a clinicopathologic study of 25 cases

Unusual Mesenchymal Tumors of the Lower Gastrointestinal Tract: When You Hear Hoofbeats in the Night, Do Not Forget the Zebras

INTRODUCTION

Little information about clinical presentation of mesenchymal tumors of the lower gastrointestinal (GI) tract due to their extreme heterogeneity is available for clinical management. Usually, small solitary asymptomatic polyps are accidently found during a screening colonoscopy performed for hematochezia, abdominal pain, constipation, diarrhea, and bowel obstruction. In this case series, we illustrate our experience with mesenchymal tumors of the lower GI tract, which are a group of unusual and quite challenging lesions.

CASE PRESENTATION

We retrospectively collected mesenchymal tumors of the lower GI tract in our institution (Fondazione IRCSS Ca' Granda - Ospedale Maggiore Policlinico di Milano) during the last 10 years. We reviewed the histological slides, and, when necessary, we performed immunohistochemical analyses to better characterize the tumors. A total of 99 cases were identified: 45 GISTs, 42 lipomas, 4 leiomyomas, 3 Kaposi sarcomas, 1 schwannoma, 1 ganglioneuroma, 1 hemangioma, 1 inflammatory fibroid polyp, and 1 challenging case of spindle cell melanoma. We focused on the most rare entities excluding therefore all GISTs and lipomas from re-evaluation.

CONCLUSION

Mesenchymal tumors of the lower GI tract represent a highly heterogeneous group of lesions encompassing GISTs, lipomas, smooth muscle tumors (leiomyoma and leiomyosarcoma), GI schwannomas, inflammatory fibroid polyps, solitary fibrous tumors, and other unusual spindle cell tumors. Immunohistochemistry and, in selected cases, molecular biology remain a useful tool which, in addition to a meticulous study of the morphology, helps the pathologist in the tangled jungle of differential diagnosis.

Gastrointestinal stromal tumor of the rectum: results of surgical and multimodality therapy in the era of imatinib

BACKGROUND

The rectum is a rare site of gastrointestinal stromal tumor (GIST), and factors determining long-term outcome remain unclear. In a population study, we assessed the outcome of rectal GIST patients treated at two referral centers.

METHODS

A total of 39 patients diagnosed with rectal GIST between January 2002 and December 2010 were identified in prospective databases. Tumor and patient characteristics, treatment details, and outcome were evaluated. Median follow-up was 41 (3-110) months.

RESULTS

A male predominance was noticed (M/F = 29/10). Median age was 53 years (range, 32-80 years). The cohort included, of 39 patients, 12 low-risk, 26 high-risk, and 1 with M1 disease. Of 38 patients with nonmetastatic disease, 36 underwent surgery as transabdominal (15 of 36) or local (21 of 36) resection. There were 21 patients who received preoperative and/or postoperative imatinib treatment. Patients with preoperative imatinib (16 of 36) had a significantly higher rate of R0 resections (p = .02). Five patients developed local recurrences. All of them had undergone local tumor excision with positive margins and without perioperative imatinib. Also, five patients suffered from distant metastases. All belonged to the high-risk group and underwent tumor surgery (3 R0, 2 R1) without receiving perioperative imatinib. A total of three patients died of disease. Perioperative imatinib was associated with improved local disease-free, disease-free, and overall survival (p < .01, p < .01, and p = .03, respectively). Local disease-free survival was significantly improved by negative resection margins (p < .01).

CONCLUSIONS

Complete resection is recommended to achieve local disease control. Preoperative imatinib was associated with improved surgical margins. Perioperative imatinib was associated with improved local disease-free, disease-free, and overall survival.

Colorectal gastrointestinal stromal tumors: a brief review

Gastrointestinal stromal tumors (GISTs) are rare lesions that constitute the majority of mesenchymal tumors in the gastrointestinal tract. Within the colon and rectum, they represent 0.1% of all cancers. They can present with a variety of symptoms but are often asymptomatic. Although many lesions may be benign, up to half of patients develop recurrent disease within a few years. Almost all GISTs contain a mutation in the c-kit tyrosine kinase that leads to its constitutive activation and results in cell proliferation. This discovery has led to the immunostaining of the c-kit antigen (CD117) to distinguish GISTs from other malignancies. Radiologic examinations can be helpful in initial diagnosis and staging. Surgery is the best treatment for cure, but recent advances have led to the use of imatinib mesylate, a tyrosine kinase inhibitor, to treat metastatic or unresectable disease, or both. There are currently many clinical trials available to help treat GISTs.