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Thread: Colonic Leiomyoma (Stromal Tumor) Pictures - Atlas of Colon and Ileum

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    Default Colonic Leiomyoma (Stromal Tumor) Pictures - Atlas of Colon and Ileum

    INTRODUCTION
    Stromal or mesenchymal neoplasms affecting the gastrointestinal (GI) tract are divided into two groups. The most common are neoplasms that are collectively referred to as gastrointestinal stromal tumors (GISTs). They are most often located in the stomach and proximal small intestine, but can occur in any portion of the alimentary tract and occasionally in the omentum, mesentery, and peritoneum .

    A far less common group of mesenchymal GI tract neoplasms is comprised of a spectrum of tumors that are identical to those that might arise in the soft tissues throughout the rest of the body. These include lipomas, liposarcomas, leiomyomas, leiomyosarcomas, desmoid tumors, schwannomas, and peripheral nerve sheath tumors.

    Local treatment options for GIST, leiomyomas, and leiomyosarcomas of the GI tract will be discussed here. The epidemiology, classification, molecular pathogenesis, clinical presentation, and diagnostic workup of GISTs, leiomyomas, and leiomyosarcomas of the GI tract, and the use of tyrosine kinase inhibitors (TKIs), both in the adjuvant and neoadjuvant setting, and for patients with metastatic GIST, are discussed elsewhere.
    Colonic Leiomyoma (Stromal Tumor) Pictures attachment.php?s=ba6c1f10d9f6a850506ccd3ccc74c62e&attachmentid=2092&d=1442251078

    GENERAL SURGICAL PRINCIPLES
    The management of GISTs, leiomyomas, and leiomyosarcomas involving the GI tract depends upon the confidence in the preoperative diagnosis, tumor location and size, extent of spread, and clinical presentation (eg, whether there is evidence of tumor obstruction, perforation, or uncontrolled hemorrhage)


    Case Material and Follow-Up
    Mesenchymal tumors from the colon and rectum that were coded as leiomyomas, leiomyosarcomas, smooth muscle tumors, or stromal tumors were retrieved from the files of the Armed Forces Institute of Pathology and the Haartman Institute of the University of Helsinki, Helsinki, Finland from 1970 to 1998 (total of 522 tumors).
    Eighty-eight tumors arose from or involved the muscularis mucosae only, and they all were composed of well-differentiated smooth muscle cells. There were no GISTs among the tumors limited to muscularis mucosae. In the same material in the two institutions, there were 37 colonic and 133 rectal primary GISTs, and 51 additional GISTs secondarily involving these sites. The series of colonic GISTs has been previously published . All except 2 of the 88 leiomyomas originally were diagnosed as leiomyomas; two tumors with atypia were diagnosed as smooth muscle tumors of uncertain malignant potential. Hematoxylin and eosin-stained slides (one to two slides of each case) were reviewed. Mitoses were searched for in each lesion.

    Clinical data were reviewed from the records, and the follow-up information was obtained from the contributing pathologists, hospital records, tumor registries and sometimes from the patients themselves. If clinical records were not available, the cause of death was obtained from the state death certificates.

    Immunohistochemistry
    Immunostains were performed on freshly cut sections on 15 tumors and of variable numbers of available unstained slides on 9 tumors; of the latter group, partial results were reviewed from the files. Also, normal colon segments from surgery for diverticulitis or carcinoma (n = 12) were evaluated immunohistochemically to find the normal distribution of CD117-, actin, desmin and CD34-positive cells. Antibodies to the following antigens were used: CD34 (QBEND-10, monoclonal, diluted at 1:80, Biogenex laboratories, San Ramon, Ca), CD117 (c-kit pro-oncogene product, a polyclonal antibody sc-168 at 1:400, Santa Cruz Biotechnology, Santa Cruz, Ca), -smooth muscle actin (1A4 monoclonal at 1:800 [Sigma Chemicals, St. Louis, Mo], desmin D33, monoclonal at 1:100 [DAKO]), and S100-protein (polyclonal antibody at 1:1600, DAKO). Studies were performed on one representative block of each case by using the avidin biotin peroxidase complex detection system with diaminobenzidine as the chromogen. Microwave epitope retrieval in sodium EDTA-buffer (372 mg/L, pH 8.0) was used before immunostaining for CD34 and CD117. The staining for CD34, CD117, smooth muscle actin and S100-protein were interpreted only when positive normal cells were present (endothelial cells, mast cells or Cajal cells, vascular pericytes, dendritic cells or nerves, respectively). This rule was not followed in the case of desmin, because normal muscle tissue was sometimes absent in the available slides. Three authors evaluated the results, and consensus was reached in each case.
    Colonic Leiomyoma (Stromal Tumor) Pictures attachment.php?s=ba6c1f10d9f6a850506ccd3ccc74c62e&attachmentid=2093&d=1442251089

    Clinical Features
    There were 88 patients with leiomyoma of muscularis mucosae. There was a significant, nearly identical male predominance in both institutions (AFIP M:F 2.6:1 and Helsinki M:F 2.4:1) suggesting that the male predominance of the military population did not skew the gender distribution. The patients' ages ranged 38 to 85 years (median 62 years). Only two patients were under 40 years of age. The age and sex distribution of the 85 cases with complete data is shown
    The leiomyomas were predominantly distally located: 21 in rectum, 36 in sigmoid, 12 in descending colon, two in transverse colon and two in hepatic flexure. The exact location in colon of 15 tumors was not available. The single hospital material from Helsinki had a ratio of colonic to rectal tumors of 12:6, whereas this ratio in AFIP material was 55:15, indicating that more tumors were located in the colon than in the rectum.

    The ratio of leiomyomas of muscularis mucosae to GISTs in colon was 12:1 in the Helsinki single hospital material and 55:36 in the AFIP material. The ratio of leiomyomas of muscularis mucosae to GISTs in the rectum was 6:6 in the Helsinki single hospital material and 15:127 in the AFIP material indicating the leiomyomas of muscularis mucosae are more common than GISTs in the colon, but equally or less common than GISTs in the rectum (although referral bias likely caused relative overrepresentation of the GISTs in the AFIP material).

    The lesions typically appeared as small sessile polyps, and were removed by endoscopic snare polypectomy. Sometimes they had a pedicle, which occasionally was as long as 7 cm. Endoscopic snare polypectomy resulted in complete tumor removal in virtually all cases. The lesional diameter ranged from 1 to 22 mm (median 4 mm). The three largest tumors measured 22 mm, 14 mm, and 13 mm. There was no evidence of specific symptoms. The colonoscopy indications were not clear from the records in all cases, but most commonly included adenoma surveillance, cancer screening or follow-up of occult blood in stool. One tumor was incidentally detected in a surgical specimen of rectum that was excised because of a mucinous adenocarcinoma.
    Colonic Leiomyoma (Stromal Tumor) Pictures attachment.php?s=ba6c1f10d9f6a850506ccd3ccc74c62e&attachmentid=2094&d=1442251100

    Pathologic Features
    The lesions were grossly described as white, firm, circumscribed nodules that formed the majority of the polyps covered by a grossly intact colonic mucosa. Histologically the lesions were composed of well-differentiated smooth muscle cells that were immediately bordering the overlying epithelium . The epithelium often showed slight pressure atrophy, with focal ulceration in one case. The lesions completely merged with the muscularis mucosae layer and appeared to originate from it . In almost all specimens, there was normal submucosa underneath the lesions, but elements of muscularis propria were never present in the endoscopic specimens. Two tumors showed marked atypia with hyperchromatic nuclei , and one of these lesions also showed a single mitosis.
    Immunohistochemically all 24 tumors that were studied were positive for smooth muscle actin and desmin with global, diffuse staining . All 20 tumors studied were negative for CD34 and CD117 (KIT), but moderate numbers of intralesional mast cells were positive for the latter. S100-protein positive elements included only small nerve twigs adjacent to tumors and scattered dendritic antigen presenting cells.
    Normal colonic tissue contained CD117-positive Cajal cell-like elements only in and around the myenteric plexus; such cells were not identified in the muscularis mucosae layer. Both muscularis mucosae and muscularis propria were uniformly positive for smooth muscle actin and desmin. In addition to endothelia, scattered fibroblasts between the smooth muscle fibers were CD34-positive.
    Colonic Leiomyoma (Stromal Tumor) Pictures attachment.php?s=ba6c1f10d9f6a850506ccd3ccc74c62e&attachmentid=2095&d=1442251111

    Follow-Up
    Information available on 29 patients showed no recurrences (median follow-up of 46 months [range 2 to 145 months]). Thirteen patients died of unrelated causes. One of the two patients whose leiomyoma had significant atypia and a mitosis, was alive and well after 5 years. Another patient whose leiomyoma showed significant atypia died of hypertensive heart disease 43 months later.

    References:
    Modern Pathology - Mesenchymal Tumors of Muscularis Mucosae of Colon and Rectum are Benign Leiomyomas that Should be Separated from Gastrointestinal Stromal Tumors[mdash]A Clinicopathologic and Immunohistochemical Study of Eighty-Eight Cases
    Local treatment for gastrointestinal stromal tumors, leiomyomas, and leiomyosarcomas of the gastrointestinal tract











    Last edited by Medical Photos; 09-14-2015 at 05:18 PM.

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