A Case of Sporadic Desmoid Fibromatosis of the Appendix: A Rare Site of Presentation

Nuclear staining for beta-catenin by immunohistochemistry is being used increasingly to diagnose desmoid tumours (deep fibromatoses), especially where the differential diagnosis includes other abdominal spindle cell neoplasms. This study aimed to define the prevalence of beta-catenin positivity in desmoid tumours and other morphologically similar spindle cell neoplasms. Nuclear beta-catenin expression was evaluated by immunohistochemistry in 270 soft tissue tumours. Nuclear immunopositivity was detected in 80% of cases of sporadic desmoid fibromatosis (24/30) and in 67% of tumours in patients with familial adenomatous polyposis (8/12). Nuclear positivity was also present in 14/25 superficial fibromatoses (56%), 3/10 low-grade myofibroblastic sarcomas (30%), 5/23 solitary fibrous tumours (22%), 1/5 infantile fibrosarcomas (20%), 1/18 desmoplastic fibroblastomas (6%) and 1/21 gastrointestinal stromal tumours (5%). No nuclear immunoreactivity was present in neurofibromas (0/26), schwannomas (0/25), nodular fasciitis (0/19), leiomyosarcomas (0/16), inflammatory myofibroblastic tumours (0/12), fibromas of tendon sheath (0/9), lipofibromatoses (0/5), Gardner fibromas (0/4), calcifying aponeurotic fibromas (0/4) or fibromatosis colli (0/1). Nuclear staining for beta-catenin is supportive, but not definitive, of the diagnosis of desmoid fibromatosis. No significant difference in immunoreactivity was observed between sporadic and familial desmoid fibromatoses. beta-Catenin negativity does not preclude the diagnosis of fibromatosis.

10568 Background: Desmoid Fibromatosis (DF) is one of a group of rare fibrous tissue proliferations (2–4 cases per year per million) which tend to be locally aggressive but have no propensity for metastasis. Gastrointestinal Stromal Tumor (GIST) is the most common mesenchymal tumors of the gastrointestinal tract and also rare (15–20 cases per year per million). Anecdotal reports of individuals with both diseases led us to investigate the number of patients at our institute with both types of cancer and their clinical, and histopathologic features. Methods: We identified four cases of GIST associated with DF at the M. D. Anderson Cancer Center between 1995 and 2008 using an IRB-approved protocol. Two more cases were identified from the patient database at the University of Helsinki. Results: Our patients were three men and three women aged from 39 to 66. Two patients were African Americans and 3 were Caucasians. In 5 cases, the GIST was diagnosed prior to the DF while one case had both tumors synchronous at presentation. The primary site of the GIST was gastric in 4 cases and the others were jejunal and mesenteric. Three patients had their DF occur in the surgical incision site mimicking a recurrence of GIST. The 3 others were intra-abdominal DF. There were no cases of DF occurring outside of the GI tract. One GIST patient was metastatic at presentation and one developed metastasis before DF was diagnosed. In 5 cases, imatinib mesylate was administered to the patients with partial response. In all cases KIT expression was observed immunohistochemically for GIST and but not for DF. Additionally, all cases of DF but no cases of GIST were found to have beta-catenin expression by immunohistochemistry. Conclusions: Our findings suggest that concurrent DF may occur in patients with GIST. Additionally, DF may mimic the recurrence of GIST or imatinib resistance. The association of these two sarcomas should be further explored. No significant financial relationships to disclose.

Background The gastrointestinal tract can be affected by both epithelial and non-epithelial tumors. When considering non-epithelial tumors, gastrointestinal stromal tumors (GISTs) are the most common with an incidence of 7–15 cases per million per year. Fibroblastic desmoid tumors, originating from mesenchymal cells, are rarer with an incidence of 2–4 cases per million per year. Despite being distinct lesions, these tumors may appear similar on imaging when they involve the stomach wall or bowel. As a result, they may be confused with one another when initially diagnosed. Aims This report aims to present a case where a desmoid tumor was mistaken for a gastric GIST despite extensive investigation prior to laparotomy. Methods Retrospective review of one patient. Results A 27-year-old gentleman presented with acute left-sided abdominal pain and postprandial fullness that began 2 days prior. A CT-abdomen/pelvis demonstrated a large exophytic mass arising from the lesser sac of the stomach, in keeping with an aggressive gastrointestinal stromal tumor (GIST). He was admitted and was further investigated with an endoscopic ultrasound, which demonstrated an exophytic hemorrhagic mass arising from the muscularis propria of the gastric wall. Again, this was most consistent with a GIST and urgent surgical resection was recommended. An exploratory laparotomy was organized the following day. There were no signs of a GIST intraoperatively, but rather a soft tissue tumor of the left mesentery of the transverse colon. This mass was resected, and a biopsy of the peritoneum was collected. Pathology identified a low-grade spindle cell tumor, CD117/CD34 negative with patchy cytoplasmic and nuclear β-catenin staining, in keeping with desmoid fibromatosis. Conclusions This case illustrates how GISTs and desmoid tumors are often mistaken for one another when associated with the stomach wall or bowel. Despite morphologic features of both tumors outlined in the literature, pathology, with focus on specific staining patterns, is necessary in many cases to distinguish the two. This distinction is paramount for appropriate prognostication and management, including timely investigation for associated diseases such as Familial Adenomatous Polyposis in patients with desmoid tumors. Funding Agencies None

Pediatric Jejunal Gastrointestinal Stromal Tumor Diagnosed by Wireless Capsule Endoscopy

The College of American Pathologists offers these protocols to assist pathologists in providing clinically useful and relevant information when reporting results of surgical specimen examinations. The College regards the reporting elements in the “Surgical Pathology Cancer Case Summary (Checklist)” portion of the protocols as essential elements of the pathology report. However, the manner in which these elements are reported is at the discretion of each specific pathologist, taking into account clinician preferences, institutional policies, and individual practice. The College developed these protocols as an educational tool to assist pathologists in the useful reporting of relevant information. It did not issue the protocols for use in litigation, reimbursement, or other contexts. Nevertheless, the College recognizes that the protocols might be used by hospitals, attorneys, payers, and others. Indeed, effective January 1, 2004, the Commission on Cancer of the American College of Surgeons mandated the use of the checklist elements of the protocols as part of its Cancer Program Standards for Approved Cancer Programs. Therefore, it becomes even more important for pathologists to familiarize themselves with these documents. At the same time, the College cautions that use of the protocols other than for their intended educational purpose may involve additional considerations that are beyond the scope of these documents.

Desmoid fibromatosis (DF) is a clonal proliferative disorder of myofibroblasts, which arises, with a low incidence, in soft tissue, including within the abdomen. The incidence of DF is associated with familial adenomatous polyposis (FAP), and is more common following FAP surgery. It is rare for a patient to make his/her first visit to hospital due to DF symptoms associated with FAP. In the present report, a case of mesenteric DF associated with FAP is described. This case also had incomplete intestinal obstruction due to DF. By summarizing previous studies examining DF and FAP treatment, combined with the disease characteristics of this patient, the clinical treatment strategy for DF associated with FAP was explored.

Desmoid fibromatosis (DF) involving the gastrointestinal tract is extremely rare. Its intramural location and occasional expansile growth pattern within the bowel wall may mimic a gastrointestinal stromal tumor (GIST). Due to the different disease behaviors and management, it is important to make a correct diagnosis before further treatment. We present an extremely rare case of a gastric DF that on imaging appeared as a discrete intramural mass mimicking a GIST and that was preoperatively correctly diagnosed as a DF based on its cytomorphologic, immunohistochemical, and molecular profiles.The patient is a 71-year-old female who presented with dysphagia and unintentional weight loss. A mass was identified at the gastric fundus. Endoscopic ultrasound-guided fine-needle aspirate (FNA) and biopsy (FNB) were performed. The FNA showed a few small aggregates of cytologically bland spindle-shaped cells with elongated nuclei. The FNB yielded small fragments of tissue composed of bland spindle cells demonstrating nuclear and cytoplasmic immunostain for β-catenin and focal stain for smooth muscle actin (SMA) and desmin. CD117, DOG1, CD34, caldesmon, S100, cytokeratin AE1/AE3, signal transducer and activator of transcription 6 (STAT6), MUC4, progesterone receptor (PR), and anaplastic lymphoma kinase (ALK) were negative, and MIB-1 showed a very low proliferation activity index. Molecular studies performed by targeted next-generation sequencing showed activating mutations in CTNNB1. These results excluded a GIST and confirmed the diagnosis of a gastric DF.Although it is very rare, DF must be included in the differential diagnosis of discrete intramural gastric spindle cell lesions. A definitive diagnosis can be made preoperatively if enough lesional material is available for appropriate immunohistochemical and molecular studies.

Introduction/Objective Small bowel Schwannoma is a benign neoplasm of nerve sheath cells. The Gastrointestinal stromal tumor (GIST) constitutes only about 1-2% of small bowel spindle cell tumors. The simultaneous presence of two tumors in the small bowel is extremely uncommon. Methods/Case Report We report a case of small bowel GIST co-existing with Schwannoma. A 64-year-old female with a known history of Neurofibromatosis was admitted for excision of a small bowel tumor. MRI of the abdomen revealed two enhancing lesions in the left upper quadrant adjacent to the small bowel. Differential considerations included GIST versus Neurofibroma. Left hemicolectomy with small bowel resection was performed. The proximal small bowel revealed GIST, spindle cell type, low risk (3.5 cm), low grade (<5 mitoses/ 5mm2). Tumor cells were diffusely reactive to CD34, CD117, and DOG1 immunostains and were nonreactive to S100 and SOX10 immunostains confirming the diagnosis of GIST. Another segment of the small bowel revealed a 1.5 cm well-circumscribed, predominantly spindle cell tumor with abundant myxoid stroma and prominent cyst formation. Tumor cells were diffusely reactive to S100 and SOX10 immunostains but nonreactive to CD34, CD117, and DOG1, favoring a diagnosis of Schwannoma. Gastrointestinal Schwannomas may be associated with Neurofibromatosis in some cases. GIST, a KIT- or PGDFRA-signaling driven mesenchymal tumor has also rarely been reported to be associated with Neurofibromatosis type 1. However, synchronous small bowel Schwannoma and GIST represent a rare co-existence of two different histopathologic subtypes of spindle cell tumors. Results (if a Case Study enter NA) NA Conclusion In summary, we present the rare co-existence of two different spindle cell lesions in Neurofibromatosis patient.

Recurrent plexiform angiomyxoid myofibroblastic tumour (PAMT) of the stomach with aggressive behaviour

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the gastrointestinal (GI) tract. GISTs account for approximately 80% of the clinically relevant GI mesenchymal tumors. Although most GISTs show spindle cell morphology, 10-15% of GISTs show pure epithelioid configuration. Therefore, not only spindle cell tumors but also epithelioid cell ones developing in the GI tract are subject to the differential diagnoses of GISTs. GISTs are basically positive for KIT, a receptor tyrosine kinase (RTK) encoded by protooncogene c-kit, by immunohistochemistry, but approximately 5% of GISTs are only weakly or barely positive for KIT. Since almost all spindle cell type GISTs are strongly and diffusely positive for KIT regardless of different genetic subtypes, diagnosis of the spindle cell type GISTs is not difficult. On the other hand, epithelioid cell type GISTs show different staining patterns of KIT in different genetic backgrounds. Approximately half of the epithelioid cell type GISTs with platelet-derived growth factor receptor alpha (PDGFRA) gene mutation might show weak or undetectable staining of KIT. On the other hand, almost all GISTs are negative for desmin, which is a positive marker for mature smooth muscle cells, and S100 protein, which is a Schwann cell marker. Smooth muscle tumors such as leiomyomas and leiomyosarcomas, which usually show the spindle cell morphology, consist of approximately 10% of the clinically relevant GI mesenchymal tumors and are almost positive for desmin and negative for KIT and S100 protein. Schwannomas which nearly always show the spindle cell pattern, comprise up to 5% of the GI mesenchymal tumors, and almost all of them are positive for S100 protein and negative for KIT and desmin. Thus, most GI mesenchymal tumors are differentially diagnosed by immunohistochemistry (IHC) of KIT, desmin and S100 protein. However, mesenchymal tumors such as desmoids, solitary fibrous tumors (SFTs), inflammatory myofibroblastic tumors (IMTs), perivascular epithelioid cell tumors (PEComas), inflammatory fibroid polyps (IFPs), rarely develop in the GI tract, and have to be correctly diagnosed through detection of specific immunohistochemical markers and/or unique genetic aberrations.

Cutaneous epithelioid and spindle cell neoplasms occasionally pose a significant diagnostic challenge on purely histologic grounds. Given the substantial clinicopathologic overlap between these lesions, especially in small biopsies, the use of immunohistochemical studies are essential. We evaluated the utility of a battery of immunohistochemical markers, including podoplanin (D2-40), CD10, p63, and wide-spectrum cytokeratin, for distinguishing cutaneous epithelioid and spindle cell tumors. A total of 81 cases, including 42 atypical fibroxanthoma (AFX), 13 spindle cell melanoma, 10 sarcomatoid carcinoma, 9 leiomyosarcoma (LMS), and 7 leiomyoma, formed the basis of our study. Immunohistochemical results were as follows-AFX: CD10 (35 of 42), p63 (1 of 42), CK (1 of 42), and podoplanin (19 of 42); spindle cell melanoma: CD10 (7 of 13), p63 (0 of 13), CK (0 of 13), and podoplanin (2 of 13); sarcomatoid carcinoma: CD10 (5 of 10), p63 (7 of 10), CK (4 of 10), and podoplanin (7 of 10); LMS: CD10 (4 of 9), p63 (0 of 9), CK (2 of 9), and podoplanin (1 of 9); and leiomyoma: CD10 (0 of 7), p63 (0 of 7), CK (0 of 7), and podoplanin (1 of 7). Our findings showed that the combination of certain immunohistochemical markers may be a useful adjunct in the evaluation of epithelioid and spindle cell tumors of the skin. In this study, we found that a combination of wide-spectrum cytokeratin and p63 are most helpful in the distinction of sarcomatoid carcinomas from other tumors; however, there remains a substantial minority of cases of sarcomatoid carcinoma that will consistently demonstrate negative staining for these markers. We also found that CD10 and podoplanin (D2-40) have limited diagnostic utility in epithelioid and spindle cell tumors of the skin; however, a strong and diffuse pattern of staining will favor the diagnosis of AFX. Caution should also be observed in the diagnosis of spindle cell malignant melanoma because some cases may express CD10, p63, and podoplanin while being nonreactive to S100 protein. Awareness of the limitations of the use of these stains and familiarity with their staining patterns in spindle and epithelioid cell tumors of the skin are extremely important because the prognostic and therapeutic implications for such neoplasms may be quite different.

There is sparse published information on computed tomographic (CT) characteristics of canine gastrointestinal tumors. The purposes of this multi-center, retrospective, descriptive study were to describe the CT features of histologically-confirmed canine gastrointestinal spindle cell, epithelial, and round cell tumorsand, when available, describe the corresponding ultrasound findings. The inclusion criteria were as follows: availability of pre-and post-contrast CT study, and a histopathological diagnosis of the lesions. Recorded parameters were tumor size, location, gastrointestinal wall layers involvement, lesion's growth and enhancement patterns, tumor margination, presence of stenosis, mineralization, ulcerations, lymphadenopathy, or other lesions in the abdomen/thorax. When available, ultrasound images were evaluated. Forty-one dogs met the inclusion criteria and had the following histological diagnoses: 21/41 (51%) spindle cells (7 leiomyomas, 14 leiomyosarcomas/gastrointestinal stromal tumors (GISTs)), 13/41 (32%) epithelial (adenocarcinoma), and 7/41 (17%) round cell (lymphoma) tumors. The growth pattern was concentric, eccentric, and mixed in epithelial, spindle cell, and round cell tumors, respectively. Spindle cell tumors had the largest main volume and involved the outer gastrointestinal layer with an unaffected inner layer. Leiomyosarcomas/GISTs showed irregular margins compared to leiomyomas. Only lymphomas showed multifocal gastrointestinal involvement. Nine carcinomas and six spindle cell tumors caused partial stenosis with secondary sub-obstruction. Mineralizations were more frequent in spindle cell tumors (10/21) and absent in lymphomas. Lymphadenomegaly was widespread in lymphomas, regional in leiomyosarcomas-GISTs and adenocarcinomas, and absent in leiomyomas. The reported CT features may be useful in prioritizing the differential diagnosis between spindle cell, epithelial, and round cell tumors, similar to those reported on ultrasound.

Canine gastrointestinal stromal tumors (GISTs) are a recent subtype of gastrointestinal spindle cell tumor recognized with the increasing use of immunohistochemistry. To our knowledge, no imaging features have been described in immunostochemically confirmed canine GISTs. The objective of this retrospective, cross-sectional study was to describe ultrasonographic features of canine GISTs compared with other spindle cell tumors. Thirty-seven dogs with an ultrasonographically visible gastrointestinal mass and a histopathologic diagnosis of spindle cell neoplasia were examined. Immunohistochemistry staining was performed for retrieved tissue samples to further differentiate the tumor type and each sample was interpreted by a single veterinary pathologist. Ultrasonographic features recorded examined included mass echogenicity, homogeneity, presence of cavitation, layer of origin, bowel wall symmetry, and loss of wall layering, location, size, vascularity, and evidence of perforation or ulceration. Tumor types included 19 GISTs, eight leiomyosarcomas, six leiomyomas, and four nonspecified sarcomas. Gastrointestinal stromal tumors were significantly more likely to be associated (P < 0.03) with abdominal effusion than other tumor types. There was overlap between the anatomical locations of all tumors types with the exception of the cecum where all eight tumors identified were GISTs. Besides location, there were no unique ultrasound features of GISTs that would allow distinction from other gastrointestinal spindle cell tumors. Similar to previous studies, GISTs appeared to be the most common spindle cell tumor associated with the cecum in our sample of dogs. The high frequency of abdominal effusion with GIST's was of unknown etiology could possibly have been due to septic peritonitis.

Background: Spindle cell lesions of gastro-intestinal tract (GIT) are relatively uncommon tumours compared to epithelial tumours. The anatomic location of spindle cell tumour is important, whether the tumour is located in mucosa, submucosa or muscularis propria.Methods: Authors endeavoured to study the histopathological spectrum of spindle cell lesions for a period of one year from January 2018 to December 2018 in our hospital.Results: This was a prospective study of 1 year starting from January 2018 to December 2018. A total of 30 cases of spindle cell lesions of gastrointestinal tract were seen. Out of 30 cases 23 were gastrointestinal stromal tumours (GIST), 2 cases were schwannomas, 2 cases were of leiomyomas, 1 case was fibromatosis, 1 case was inflammatory fibroid polyp, and one case was inflammatory myofibroblast tumour.Conclusion: GISTs are the commonest spindle cell tumours of GIT. Besides GIST, there are other spindle cell tumours which range from benign to malignant, and need to be differentiated from GIST for proper management.

An Unusual Cause of Recurrent Subepithelial Mass in the Stomach