S-100 Reactivity Research Articles

Case Report: Schwannoma of the tongue

Schwannomas are benign neoplasms originating from Schwann cells of the peripheral nerve sheath. Intraoral lesions are uncommon. A 58-year-old female patient complained of discomfort at the apex of the tongue. Clinical examination revealed a fibrous, lobulated, delimited, and normochromatic nodular lesion, measuring 3 centimeters in diameter, with 10 years of evolution. Diagnostic hypotheses included schwannoma and neurofibroma, thus, an excisional biopsy was performed. Microscopic analysis showed a proliferation of fusiform cells organized in a more cellularized area, with a palisade arrangement around acellular areas, and a less cellularized area, with dispersed cells, intermingled with loose connective tissue. The neoplastic cells were positive for immunohistochemical reactions for S100, confirming the diagnosis of schwannoma. The patient remained without symptoms and with no signs of recurrence after 18 months of follow-up. The correlation of clinical signs and symptoms is essential for the elaboration of the differential diagnosis, treatment planning, and diagnosis confirmation. Schwannomas are benign neoplasms originating from Schwann cells of the peripheral nerve sheath. Intraoral lesions are uncommon. A 58-year-old female patient complained of discomfort at the apex of the tongue. Clinical examination revealed a fibrous, lobulated, delimited, and normochromatic nodular lesion, measuring 3 centimeters in diameter, with 10 years of evolution. Diagnostic hypotheses included schwannoma and neurofibroma, thus, an excisional biopsy was performed. Microscopic analysis showed a proliferation of fusiform cells organized in a more cellularized area, with a palisade arrangement around acellular areas, and a less cellularized area, with dispersed cells, intermingled with loose connective tissue. The neoplastic cells were positive for immunohistochemical reactions for S100, confirming the diagnosis of schwannoma. The patient remained without symptoms and with no signs of recurrence after 18 months of follow-up. The correlation of clinical signs and symptoms is essential for the elaboration of the differential diagnosis, treatment planning, and diagnosis confirmation.

EXTRANEURAL PERINEURIOMA OF THE MANDIBLE - A CASE REPORT

A 36-year-old female patient was referred to a private clinic presenting an asymptomatic, intraosseous lesion in the posterior right mandible. Itraoral examination revealed no significant alteration. X-rays and cone-beam computed tomography exams revealed a well-defined, radiolucent, hypodense lesion with a sclerotic border in the right side of the mandible. The tumor appeared to cause fusiform enlargement of the mandibular canal. After an incisional biopsy, histopathological analysis revealed a proliferation of slender, spindle-shaped cells with long cell processes arranged in storiform and short-fascicular patterns. The findings were suggestive of extraneural perineurioma. Immunohistochemical reactions for S100, EMA, and Glut-1 antigens confirmed the diagnosis. The tumor was resected under general anesthesia. Follow-up is still ongoing. Funding: CAPES/Brazil; FAPEMIG/Brazil; CNPq/Brazil. A 36-year-old female patient was referred to a private clinic presenting an asymptomatic, intraosseous lesion in the posterior right mandible. Itraoral examination revealed no significant alteration. X-rays and cone-beam computed tomography exams revealed a well-defined, radiolucent, hypodense lesion with a sclerotic border in the right side of the mandible. The tumor appeared to cause fusiform enlargement of the mandibular canal. After an incisional biopsy, histopathological analysis revealed a proliferation of slender, spindle-shaped cells with long cell processes arranged in storiform and short-fascicular patterns. The findings were suggestive of extraneural perineurioma. Immunohistochemical reactions for S100, EMA, and Glut-1 antigens confirmed the diagnosis. The tumor was resected under general anesthesia. Follow-up is still ongoing. Funding: CAPES/Brazil; FAPEMIG/Brazil; CNPq/Brazil.

A Rare Case of a Primary Leiomyoma of the Clivus in an Immunocompetent Patient and a Review of the Literature Regarding Clival Lesions

Leiomyomas are common lesions that are usually located in the genitourinary and gastrointestinal tracts. Primary leiomyomas at the skull base are uncommon. They are composed of well-differentiated smooth muscle cells without cellular atypia. The diagnosis of a leiomyoma has to be confirmed by immunohistochemistry. The tumor tissue is immunoreactive for SMA, S100 and cytokeratin. Leiomyomas mainly occur in immunocompromised patients. Most tumor tissues are positive for EBV. The presented case is that of a 56-year-old immunocompetent woman with a tumor on the clivus. The radiological images suggested chordoma or fibrous dysplasia. Transnasal transsphenoidal surgery was performed. The tumor tissue consisted of well-differentiated smooth muscle cells with elongated nuclei. Immunohistochemistry revealed a positive reaction for desmin, SMA and h-Caldesmon and a negative reaction for S100, beta-catenin, PGR and Ki67. The leiomyoma diagnosis was subsequently established. To the best of our knowledge, the case of a primary leiomyoma on the clivus of an immunocompetent patient is the first to be described. We also extensively reviewed the literature on the immunohistopathological and radiological differential diagnosis of clival lesions.

An NTRK-1-associated soft tissue tumor showing distinctive nodules with peripheral accentuation of cellularity.

Lipofibromatosis-like neural tumor is a recently described entity defined by a low-cellularity spindle cell infiltrate in the subcutaneous fat with admixed inflammatory cells. This tumor is histopathologically similar to lipofibromatosis, but unlike lipofibromatosis shows reactivity for S100 and has an NTRK-1 kinase fusion. These lesions are locally aggressive but appear to have a negligible metastatic potential. Subsequently, a more cellular variant has been described with generally low mitotic rate. This variant also displays S100 reactivity and kinase fusions (typically involving NTRK-1), but it has a low risk of metastasis. In this report, we describe a case that aligns with the more cellular variant of NTRK-1 kinase fusion tumors on histopathologic, immunohistochemical, and molecular grounds, but in addition has distinctive nodules with peripheral accentuation of cellularity, reminiscent of those present in epithelioid malignant peripheral nerve sheath tumors. This latter feature is previously undescribed in NTRK kinase fusion soft tissue tumors and offers further support for the presumed neural differentiation of this neoplasm.

S1788 Pancreatic Schwannoma: A Rare Pancreatic Tumor

Introduction: Schwannomas or Neurilemmomas are encapsulated tumors of the peripheral nerve sheath. Most schwannomas are sporadic but about 10% are associated with familial neurofibromatosis type 2. Schwannoma may occur in spinal nerve roots, internal organs, or soft tissues. The extrapancreatic nerve plexus may give rise to pancreatic schwannomas. Pancreatic schwannoma is a rare tumor that can mimic other pathologic entities with a more aggressive course such as neuroendocrine tumor or gastrointestinal stromal tumor making preoperative diagnosis critical. Case Description/Methods: A 21-year-old otherwise healthy female with a history of smoking presented with abdominal pain to the emergency department. She had no nausea, vomiting or fever and urine pregnancy test was negative. The abdomen was soft and non-tender with no masses or bruit and bowel sounds were normal. Given the unexplained pain, abdominopelvic computed tomography (CT) scan was performed. A 2.7 x 2.5 cm mass inferior to the pancreatic tail. The patient was referred for Endoscopic Ultrasonography (EUS). On EUS a round hypoechoic extraluminal lesion was visualized from the second portion of the duodenum. The lesion had a well-defined outer margin, with intact interface seen between the lesion and the pancreas. The lesion was abutting the portal vein with intact interface between the lesion and the vein. The rest of the pancreas showed no significant endosonographic abnormalities with normal pancreatic duct. Endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) was performed using a 25 gauge biopsy needle. Rapid on-site evaluation (ROSE) was suggestive of a stromal cell neoplasm. Final pathological examination showed groups of bland spindle cells with no nuclear atypia, mitotic activity or necrosis and immunohistochemistry revealed diffuse immunoreactivity for S100 and focal reactivity for SOX10, CD117, and SMA consistent with the diagnosis of schwannoma (Figure). Discussion: Pancreatic Schwannoma is rare, with less than 100 reported cases in the literature. Pancreatic Schwannoma most commonly presents with abdominal pain. EUS with tissue acquisition allows for a definitive diagnosis of solid pancreatic lesions. Preoperative diagnosis of pancreatic masses is critical for appropriate surgical planning and follow-up. This case showcases a typical clinical course for pancreatic schwannoma and serves as a reminder to keep a broad differential diagnosis and appropriate workup, particularly with incidental or unexpected findings on imaging.Figure 1.: A: EUS, B: H&E, C: S100.

Increased nuclear translation of YAP might act as a potential therapeutic target for NF1-related plexiform neurofibroma.

Plexiform neurofibroma (pNF) in the head and neck is a characteristic feature in patients with neurofibromatosis type 1 (NF1) and is associated with significant disfigurement and psychological distress. Yes-associated protein (YAP), the key molecule involved in the Hippo pathway, is a vital transductor that regulates the proliferation and remyelinating of Schwann cells. The functional status of YAP and its feasibility as a potential target are still unknown in pNF. A total of 17 pNF tumor tissue specimens from the head and neck were collected at the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine. Histologically, diagnosis of the Schwann cell region in pNF was achieved with hematoxylin-eosin staining, positive reactions for S100, SOX10, ERK and p-ERK, and low identification of Ki67 and SMA. Compared with normal nerve tissue, obviously increased nuclear YAP was detected in the Schwann cell region of pNF, with a mean nuclear staining rate of 67.11%. Based on the shNF1 Schwann cell model (the RSC96 cell line), with upregulated expression of RAS, ERK and p-ERK, p-YAP (Ser127) and p-YAP (Ser397) were significantly decreased and total YAP and nuclear YAP were increased. According to a confocal assay, the interference of shNF1 substantially promoted YAP nuclear translocation. Compared with control Schwann cells, the YAP inhibitor CA3 might have a more sensitive effect (IC50: NC=0.96±0.04, shNF1=0.71±0.02, P<0.05) on the shNF1 Schwann cell model than the classic MEK1/2 inhibitor selumetinib (IC50: NC=14.36±0.95, shNF1=24.83±0.98, P>0.05). For in vivo inhibition, the CA3 group and the selumetinib group displayed a similar inhibition effect with no significant difference. Increased nuclear translation and the functional state of YAP implies that the YAP-Hippo pathway might play an important role in the formation and remyelination of pNF. Compared with selumetinib, the YAP inhibitor can exhibit a similar but more sensitive effect on NF1-/- Schwann cells. These observations imply that YAP as a novel or adjuvant therapy target in the treatment of pNF.

Host tissue response to floating microelectrode arrays chronically implanted in the feline spinal nerve

Objective. Neural interfacing technologies could significantly improve quality of life for people living with the loss of a limb. Both motor commands and sensory feedback must be considered; these complementary systems are segregated from one another in the spinal nerve. Approach. The dorsal root ganglion-ventral root (DRG-VR) complex was targeted chronically with floating microelectrode arrays designed to record from motor neuron axons in the VR or stimulate sensory neurons in the DRG. Hematoxylin and eosin and Nissl/Luxol fast blue staining were performed. Characterization of the tissue response in regions of interest and pixel-based image analyses were used to quantify MAC387 (monocytes/macrophages), NF200 (axons), S100 (Schwann cells), vimentin (fibroblasts, endothelial cells, astrocytes), and GLUT1 (glucose transport proteins) reactivity. Implanted roots were compared to non-implanted roots and differences between the VR and DRG examined. Main results. The tissue response associated with chronic array implantation in this peripheral location is similar to that observed in central nervous system locations. Markers of inflammation were increased in implanted roots relative to control roots with MAC387 positive cells distributed throughout the region corresponding to the device footprint. Significant decreases in neuronal density and myelination were observed in both the VR, which contains only neuronal axons, and the DRG, which contains both neuronal axons and cell bodies. Notably, decreases in NF200 in the VR were observed only at implant times less than ten weeks. Observations related to the blood-nerve barrier and tissue integrity suggest that tissue remodeling occurs, particularly in the VR. Significance. This study was designed to assess the viability of the DRG-VR complex as a site for neural interfacing applications and suggests that continued efforts to mitigate the tissue response will be critical to achieve the overall goal of a long-term, reliable neural interface.

Cutaneous leiomyosarcoma /&#x0D; atypical smooth muscle sarcoma

Relevance: Cutaneous leiomyosarcoma is a rare primary&#x0D; dermal neoplasm, accounting for up to 2-3% of all superficial&#x0D; sarcomas. It can occur at any age, most likely between the ages&#x0D; of 50 and 70 years. This tumor has a high recurrence potential&#x0D; in case of insufficiently deep excision. Recurrent tumors are&#x0D; more aggressive and characterized by subsequent metastasis.&#x0D; The purpose of the study was to demonstrate the results&#x0D; of the histopathological examination of a cutaneous leiomyosarcoma / atypical smooth muscle tumor.&#x0D; Results: Cutaneous leiomyosarcoma was represented by&#x0D; spindle-shaped cells with high cellularity located in bundles&#x0D; and growing expansively, surrounded by a capsule. The nuclei&#x0D; of the cells were elongated, hyperchromic. Cells with atypical&#x0D; abnormal nuclei were present in smaller quantities. The mitoses, including atypical, were numerous. IHC staining for SMA,&#x0D; Desmin, H-Caldesmon – diffusely positive on tumor cells. The&#x0D; reaction for S100, Myogenin – negative.&#x0D; Conclusion: A cutaneous leiomyosarcoma can be finally&#x0D; diagnosed only after a pathomorphological examination of&#x0D; the specimen and differential diagnostics using additional research methods.

Cutaneous leiomyosarcoma/&#x0D; atypical smooth muscle sarcoma

Relevance: Cutaneous leiomyosarcoma is a rare primary dermal neoplasm, accounting for up to 2-3% of all superficial&#x0D; sarcomas. It can occur at any age, most likely between the ages of 50 and 70 years. This tumor has a high recurrence potential&#x0D; in case of insufficiently deep excision. Recurrent tumors are more aggressive and characterized by subsequent metastasis.&#x0D; The purpose of the study was to demonstrate the results of the histopathological examination of a cutaneous&#x0D; leiomyosarcoma / atypical smooth muscle tumor.&#x0D; Results: Cutaneous leiomyosarcoma was represented by spindle-shaped cells with high cellularity located in bundles&#x0D; and growing expansively, surrounded by a capsule. The nuclei of the cells were elongated, hyperchromic. Cells with atypical&#x0D; abnormal nuclei were present in smaller quantities. The mitoses, including atypical, were numerous. IHC staining for SMA,&#x0D; Desmin, H-Caldesmon – diffusely positive on tumor cells. The reaction for S100, Myogenin – negative.&#x0D; Conclusion: A cutaneous leiomyosarcoma can be finally diagnosed only after a pathomorphological examination of the&#x0D; specimen and differential diagnostics using additional research methods

Microglandular adenosis of the breast: A case report and a highlight on main diagnosis and management aspects

Microglandular adenosis (MA) is a basically benign–recently borderline-breast disease which mimics well differentiated breast carcinoma clinically and pathologically. The incidence of carcinoma associated with MA reaches up to 27%. In this manuscript, we present a 64-year-old female patient presented with a right breast swelling. Sonomammogram revealed a breast imaging, radiology, and data system IVa right breast architectural distortion. Breast magnetic resonance imaging showed a heterogeneous segmental non mass enhancement in the upper outer quadrant with less extension to lower outer quadrant. Core needle biopsy revealed small uniform glandular structures lined by single layer cuboidal cells with luminal eosinophilic secretions. The cells showed positivity for cytokeratin (CK) and S-100 while P63, smooth muscle actin and CK5/6 were negative. Wide local excision of the mass was done. Microscopic examination revealed proliferation of small glands surrounded by collagenous stroma, some of them infiltrated into the adipose tissue, these glands were lined by a single layer of epithelial cells that lacks a myoepithelial cell layer. They showed positive reaction for S100 and were negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. This led to the diagnosis of breast MA. MA should be considered as a precursor for malignancy rather than an innocent lesion. Adequate surgical excision is recommended.

Sinonasal mucosal melanoma: A 9-year experience from a tertiary-cancer centre in South India

Sinonasal tract malignancies are uncommon, representing not more than 5% of all head and neck neoplasm. Primary sinonasal mucosal melanomas (SNMM) are rare and constitute 1% of all melanomas and about 4% of all sinonasal tumors. Mucosal melanomas are biologically distinct from cutaneous melanomas. Etiology of mucosal melanomas is still under speculation. We retrieved nine cases of SNMM from our archives over a period of 9 years from 2010 to 2018. The aim was to identify the clinical characteristics, histopathological features, disease progression, and treatment of this disease. The most common symptom was epistaxis. The mean duration of symptoms was 3 months. Nasal cavity along with maxillary sinus was the most common site. The male to female ratio was 4:5 and the mean age was 63 years. The tumors showed varying histomorphology including epithelioid, spindle cell, and undifferentiated types. Immunohistochemical studies confirmed the diagnosis with positive reactions for S100 and melanocytic markers HMB45, Melan A. Surgery was the first line of management with postoperative radiotherapy (RT) for margin positive cases. Three inoperable cases were given palliative RT. Four cases developed recurrence. Recurrences were managed with RT in most cases. Three patients died due to disease. The 1 year recurrence-free survival (RFS) rate was 44% and 2 years' RFS rate was 22%. The 5-year overall survival rate was 28%. More studies are required to understand the utility of chemotherapy and immunotherapy in treatment of this rare entity. Multi-institutional studies are needed for better understanding this rare malignancy.

Canine Oral Osteocartilaginous Malignant Amelanotic Melanoma with Pulmonary Metastasis

Background: Melanomas are typically malignant neoplasms commonly observed in the oral cavity of dogs. The classical presentation of melanomas with characteristic melanin pigmentation is easy to diagnose; however, in some cases, the lack of melanin production in the amelanotic oral tumors cause a delay in establishing the precocious diagnosis and consequent treatment. The aim of this report was to evaluate the histopathological and immunohistochemical aspects of an oral amelanotic melanoma with osteocartilaginous formation and metastasis in a dog, in a temporal way.Case: A 10-year-old male German Shepherd dog, presenting mouth bleeding with an amelanotic melanoma located between the upper incisors was received at the Veterinary Hospital of the Catholic University Dom Bosco (UCDB), Campo Grande, MS, Brazil. The animal was clinically evaluated and radiography was performed. The tumor was surgically removed and a sample was collected for histopathological examination that revealed spindloid and some epithelioid morphological cell types surrounded by a fibromatous matrix with moderate amounts of fibrovascular stroma. Approximately 1 month after surgical removal, recovery of the tumor was observed, and a second clinical analysis and collection of sample were performed. These procedures were repeated three times showing the same histopathological characteristics added by myxoid, chondroid, fibromatous tissue, and small groups of chondrocytes as well as central areas of irregular mineralized spicules. X-ray examination revealed proliferative and lytic bone infiltration in the jaw. Immunohistochemical analysis for melanocytic differentiation markers was performed showing positivity to Melan-A, tyrosinase and HMB-45 immunoreactivity, while no S100 reactivity was detected. After 11 months of the first biopsy, pleural effusion and radiopaque disseminated nodules of 1cm in the lungs were detected by X-ray. The animal died and necropsy was conducted. Multiple masses were observed in the lung and at the parietal pleura, suggesting lung metastasis by the positivity for Melan-A.Discussion: The dog was first diagnosed with fibromatous epulis based on the observation of fibroblastic tissue and spindle cells with intense vascularization associated to the site of the tumor and its macroscopic aspect. In the subsequent follow-ups the tumor displayed malignant characteristics observed by recurrence after each surgery, as the tumor returned even larger, aggressive, and infiltrative. From the second biopsy, the histopathological analysis showed the undifferentiated character of epithelioid neoplastic cells, demonstrated by the increase of cartilage and osteoid tissue and the mineral deposit. The phenomenon of the tumor stroma to form cartilage and bone is highlighted here because myxoid change and cartilage formation were frequently observed at the site where amelanotic spindle cells were actively proliferating. It is possible that neoplastic melanocytic cells themselves were involved in the development of the osteocartilaginous areas. Although no cytoplasmic melanin pigmentation was found in the tumor fragments, specific melanocytic markers for melanoma detected neoplastic melanocytes and unmelanized melanosomes. The positive reaction for Melan-A, HMB-45, and tyrosinase in the epithelioid, spindle, and cartilaginous cell groups of the neoplasia indicated amelanotic melanoma with osteocartilaginous differentiation. The negative HMB-45, S100, and tyrosinase expression in lung metastasis may be due to the fact that melanomas express aberrant markers and are also known to display occasional loss of their classic immunophenotype. Amelanotic melanoma can be underdiagnosed due to rapid progression of the tumor allied to the dedifferentiation ability of melanocytes. Thus, the follow up study of cell morphology and immunohistochemical analysis for melanogenic factors can be important determinants in diagnosis.

Metaplastic breast carcinoma with chondroid differentiation: a rare variant of infiltrative carcinoma in a 38-year-old woman

Metaplastic breast carcinoma (MBC) is a rare type of invasive breast carcinoma, and chondroid differentiation is even rarer. Here we report a case of MBC with extensive chondroid differentiation in...

Expression of S100 Protein in CD4-positive T-cell Lymphomas Is Often Associated With T-cell Prolymphocytic Leukemia.

S100 T-cell lymphomas are infrequent, and except 1 all have been CD4 negative. On the basis of an index case of CD4 S100 T-cell prolymphocytic leukemia (T-PLL), we studied S100 protein expression in 19 additional T-PLLs and 56 other T-cell lymphomas that are usually CD4, including 15 angioimmunoblastic T-cell lymphomas, 24 anaplastic large cell lymphomas (16 ALK and 8 ALK), 7 mycosis fungoides/Sézary syndrome, and 10 peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS). Two additional S100 CD4 PTCL, NOS cases were also reviewed. Thirty percent (6/20) of T-PLLs were S100 compared with 0/56 other T-cell lymphomas with previously unstudied S100 reactivity (40 CD4, 2 CD8, 11 CD4/CD8, 3 unknown) (P=0.0007). There were no significant differences between the S100 and S100 T-PLLs with regard to the male:female ratio (2:1 vs. 1:1), age (71.6±7.7 vs. 65.4±9.3), peripheral blood lymphocyte count (67.2±116.6 vs. 101.1±159.7×10/L), or median survival (463 vs. 578 d, where known). The 2 S100 PTCL, NOS cases occurred in a 7-year-old boy and a 45-year-old woman. Both had involvement of the bone marrow and peripheral blood but were morphologically unlike T-PLL and lacked TCL1 gene rearrangement. These results demonstrate that S100 T-cell lymphomas include a subset that are CD4 and most often, but not exclusively, are T-PLL. Although having diagnostic implications, there were no documented clinical differences between the S100 and S100 T-PLLs.

Immunohistochemical Analysis and Electron Microscopy of Glial Cells in the Pancreas of Fetuses and Children.

Schwann cells forming peri-insular glial sheath of the pancreatic islets in some mammals can be involved in the pathogenesis of diabetes mellitus. Human pancreatic cells contain small elongated or oval cells of unknown origin with S100-immunopositive processes. We found that cells with processes located in pancreatic islets of human fetuses and children are similar to Schwann cells by their morphological and ultrastructural characteristics, immunopositive reaction for S100, and integration with nerve endings. In the pancreas of fetuses and children, Schwann cells are often seen in forming pancreatic islets and around the pancreatic ducts. The data suggests that Schwann cells can participate in the morphogenesis of human pancreatic islets.

A Case of Extra-Skeletal Intracranial Chondromass: Ultrastructure and Immunohistochemical Features

The discrete microvasculature environment of the perivascular plays a dominant role in regulating stem cell activity and its proliferation behavior. Mesenchymal stem cells (MSC) reside in perivascular compartment, hence have the potential to contribute to the pathogenesis of extra-skeletal intracranial chondroma (ESICC). In this case report, for the first time, the immunohistochemical (IHC) markers and transmission electron microscpoe (TEM) features of perivascular are presented in ESICC. Microscopic examination revealed a well-differentiated chondroma with foci of ossification and islands of vacuolated-cells encircling thin-walled capillaries. TEM showed transitional morphological features suggestive of transformation to chondrocytes, with vacuolated cells. A subpopulation of spindle vacuolated-cells displayed reaction for S-100, ferritin, trypsin-anti-chymotrypsin and Vimentin. As there was no evidence of transitional forms to arachnoid cells, it can be concluded that the origin of the recognized ICC is a perivascular multipotential mesenchymal cell, MSC.

Granular Cell Tumor of the Ascending Colon: A Case Report and Review

Introduction: Granular cell tumor (GT) is an uncommon benign soft tissue neoplasm that is typically located on the skin, tongue, breast, and gastrointestinal (GI) tract. The GI tract is involved in roughly 10% of the cases, with 65% of those arising in the esophagus. The duodenum and stomach are the next most common locations in the GI tract, with the colon and rectum having the least incidences of this type of soft tissue tumor. These tumors are often asymptomatic and are found incidentally during screening colonoscopy. Case Report: A 36-year-old man with 2 episodes of blood per rectum presented to the ambulatory surgical center for a diagnostic colonoscopy. On examination, the proximal ascending colon revealed a 2.5-cm submucosal, pale-colored, polypoid lesion on a talk. The surface of the polyp was smooth and a central depression was present (Figure 1). The polyp was resected using the endoscopic mucosal resection (EMR) technique. Histopathology of the polyp revealed many histiocyte-like cells with granular eosinophilic cytoplasm (Figure 2). The cells stained positive with periodic acid-Schiff. Immunohistochemistry showed S-100 reactivity, thus confirming the diagnosis of a GCT.Figure 1Discussion: Granular cell tumors were first described by Weber in 1854 as a gathering of large cells with granular eosinophilic cytoplasm. The neuronal origin of the tumor was first discovered in 1952 by Feyrter. On endoscopy, these tumors are typically sessile, have a yellow tint and a slight rough surface. Histopathology of the tumor has characteristic histiocyte-like cells with PAS positive granular eosinophilic cytoplasm and small uniform nuclei in which mitotic features are not present. They stain positive for S-100 protein. Endoscopic removal is often sufficient if the tumor is less than 2 cm. In the event that pathology specimen has positive margins, further surgical resection is required. If there are multiple tumors or if there is increased risk of malignancy, follow-up colonoscopy is highly recommended. Although exceedingly rare, GCT is an important consideration in the differential diagnosis of colonic lesions.

Localization of S-100 proteins in the testis and epididymis of poultry and rabbits.

The present investigation was conducted to demonstrate S-100 protein in the testis and epididymis of adult chickens, Sudani ducks, pigeons, and rabbits. This study may represent the first indication for the presence of S-100 in the male reproductive organs of these species and might therefore serve as a milestone for further reports. In the testis of chickens, pigeons and rabbits, intense S-100 was seen in Sertoli cells. S-100 was also seen in the endothelial lining of blood vessels in rabbit testis. On the contrary, no S-100 reaction was detected in the Sertoli cells of Sudani ducks. In epididymis, the localization of S-100 had varied according to species studied; it was seen in the basal cells (BC) of epididymal duct in duck, non-ciliated cells of the distal efferent ductules in pigeons and ciliated cells of the efferent ductules and BC of rabbit epididymis. Conversely, S-100 specific staining was not detected in the epithelial lining of the rooster and pigeon epididymal duct as well as the principal cells of the rabbit epididymis. In conclusion, the distribution of the S-100 proteins in the testis and epididymis might point out to its roles in the male reproduction.

PP017: Clinicopathologic factors affecting outcome in salivary gland Acinic Cell Carcinoma and newly described mammary analogue secretory carcinoma

Purpose Mammary Analogue Secretory Carcinoma (MASC) is a newly characterized neoplastic process commonly misdiagnosed as Acinic Cell Carcinoma. Although well-characterized genetically, little information exists regarding the clinicopathologic factors affecting outcome in patients with this disease process. Acinic Cell Carcinoma is a rare entity, and clinicopathologic data has been elucidated from studies with relatively small patient populations. We aim to better understand the characteristics affecting outcome in Acinic Cell Carcinoma patients, and to compare these with patients that have been re-classified with MASC. Materials and Methods Twenty-one patients diagnosed with Acinic Cell Carcinoma were identified from the Medical University of South Carolina cancer registry. Pathological specimens from each patient were then analyzed using fluorescence in situ hybridization (FISH) to detect the ETV6-NRTK3 (12;15) (p13;q25) translocation, which is diagnostic of MASC. Furthermore, radiographic findings were also reviewed for each patient. Demographic information, primary site, presenting symptoms and tumor staging characteristics were obtained along with treatment, recurrence and outcome data for each identified case. Results All patients were treated with primary surgical excision, eleven of which also received adjuvant treatment. The average age at diagnosis was 50.4 years. Parotid glad was the most common site (95%), with one patient demonstrating disease in a minor salivary gland. The majority of patients were female (76%), and most patients were stage I (48%). However, 60% of male patients, and 19% of female patients demonstrated Stage IV disease. Eight patients from our cohort showed increased s100 reactivity, thus making them candidates for FISH analysis. At this point, one case of MASC has been identified with two more cases still to be analyzed. Our confirmed case of MASC was Stage I, which received only primary surgical treatment. Conclusions Although thought to be slightly more aggressive, MASC may have similar clinical outcomes compared to Acinic Cell Carcinoma.

The Profile of Acinic Cell Carcinoma After Recognition of Mammary Analog Secretory Carcinoma

To determine the influence of the newly described mammary analog secretory carcinoma (MASC) with ETV6 translocation on our understanding of salivary acinic cell carcinoma (AciCC), we reviewed 81 cases of AciCC: 64 "classic" AciCCs, 11 AciCCs with high-grade transformation (HGT), and 17 zymogen granule poor AciCCs. ETV6 fluorescence in situ hybridization revealed that classic AciCC (7 of 7 tested) and AciCC-HGT (4 of 4 tested) have intact ETV6. However, 10 of 17 zymogen granule poor AciCCs showed ETV6 translocation and were reclassified as MASC; the diagnosis of AciCC was retained for cases with intact ETV6. MASCs were distinguished by the lack of zymogen granules, mucin production, and stronger S100 reactivity. MASC showed a striking male predilection (male-to-female ratio, 8:2) in contrast to AciCC (male-to-female ratio, 1:1.5; P<0.01). Compared with cases of confirmed AciCC, AciCC-HGT occurred in older patients (mean age of 66.2 y vs. 47.7 y, P=0.007) and showed a poorer mean overall survival [40.2 mo (95% confidence interval (CI), 7.5-73 mo) vs. 125 mo (95% CI: 98-151 mo); P<0.001]. Patients with confirmed AciCC without HGT showed a recurrence rate of 15% (9/60) and a 7.9% (3/38) incidence of regional lymph node involvement. It appears that more than half of zymogen granule poor AciCCs are likely to represent MASC. Even after excluding cases of MASC, the presence of HGT in AciCC predicts poorer overall survival.