Spindle-shaped Mesenchymal Cells Research Articles

A Rare Case Of Early Gastrointestinal Stromal Tumor In 34-Year-Old Woman: A Caution For Adnexal Tumor Mimicry

Introduction: Gastrointestinal Stromal Tumors (GISTs) are the leading type of mesenchymal tumor in the gastrointestinal (GI) tract, constituting 80% of these tumors and 0.1% to 3% of all gastrointestinal malignancies. They arise from spindle-shaped mesenchymal cells known as interstitial cells of Cajal. Its onset can be at any age, with the peak occurring in the sixth decade. Case Presentation: We report the case of a 34-year-old woman with a complaint about a lump in her lower abdomen that has been progressively enlarging over the past year without any significant symptoms following the lump. Findings in the ultrasound suggest an ovarian mass. Laparotomy was carried out, and while no ovarian mass was found, instead a mass was identified in the mesentery of the small bowel. As a result, a complete excision of the tumor was performed, with histopathologic and immunohistochemical results confirming a GIST diagnosis. Conclusion: Representing a tiny percentage of gastrointestinal tumors, GISTs are rare. GISTs may be asymptomatic or present without any typical symptoms. Sole reliance on clinical and radiological investigations can cause them to be easily overlooked. Awareness of GIST is critical and care must be taken in diagnosis since other tumor can mimic GISTs in endoscopic, imaging, and histological findings.

Central giant cell granuloma in the posterior region of mandible mimicking a fibro-osseous lesion and hemangioma: a case report

BackgroundA central giant cell granuloma (CGCG) is a benign, proliferative, intraosseous, and non-odontogenic lesion occurring primarily in children and young adults. On the histological level, it is characterized by numerous multinucleated giant cells scattered randomly throughout a sea of spindle-shaped mesenchymal stromal cells which are dispersed throughout the fibrovascular connective tissue stroma containing areas of haemorrhage. When it comes to radiographic features, CGCG can have an array of variations, ranging from well-defined expansile lesions to ill-defined and destructive lesions, with or without expansion.Case presentationThis case report reviews an 11-year-old Caucasian patient with a chief complaint of slow-growing swelling involving the right posterior mandibular region. The cone beam computed tomography (CBCT) revealed an ill-defined mixed lesion mimicking both fibro-osseous lesion and hemangioma. However, microscopic examination revealed multinucleated giant cells in a fibrous stroma suggestive of central giant cell granuloma.ConclusionOur intent in reporting this case is to highlight the importance of thorough clinical, radiographical and histopathological examination for accurate diagnosis and therapeutic interventions as well as to emphasize the importance of taking different possibilities into consideration when examining bony swellings in the head and neck region.

Sphingomyelin is involved in regulating UCP1-mediated nonshivering thermogenesis

Adipogenesis is one of the major mechanisms for adipose tissue expansion, during which spindle-shaped mesenchymal stem cells commit to the fate of adipocyte precursors and differentiate into round-shaped fat-laden adipocytes. Here, we investigated the lipidomic profile dynamics of ex vivo-differentiated brown and white adipocytes derived from the stromal vascular fractions of interscapular brown (iBAT) and inguinal white adipose tissues. We showed that sphingomyelin was specifically enriched in terminally differentiated brown adipocytes, but not white adipocytes. In line with this, freshly isolated adipocytes of iBAT showed higher sphingomyelin content than those of inguinal white adipose tissue. Upon cold exposure, sphingomyelin abundance in iBAT gradually decreased in parallel with reduced sphingomyelin synthase 1 protein levels. Cold-exposed animals treated with an inhibitor of sphingomyelin hydrolases failed to maintain core body temperature and showed reduced oxygen consumption and iBAT UCP1 levels. Conversely, blockade of sphingomyelin synthetic enzymes resulted in enhanced nonshivering thermogenesis, reflected by elevated body temperature and UCP1 levels. Taken together, our results uncovered a relation between sphingomyelin abundance and fine-tuning of UCP1-mediated nonshivering thermogenesis.

Solitary fibrous tumor: Two cases report with a focus on the differential diagnosis

Solitary fibrous tumor (SFT) is a neoplasm of fibroblastic/myofibroblastic origin with intermediate biological behavior. We report here two cases of SFT affecting an unusual anatomical site in 58-year-old and 40-year-old female patients and discuss the differential diagnosis of this lesion. In case 01, the lesion showed the clinical appearance of an asymptomatic “blister” with normal color, rubbery consistency, measuring 0.3 cm, and affected the lower lip; while in case 02, a symptomatic red nodular lesion with a soft consistency and measuring 0.5 cm affected the floor of the mouth. Excisional biopsies were performed. Microscopically, two well-delimited benign neoplasms were observed, exhibiting the proliferation of ovoid to spindle-shaped mesenchymal cells, vascular spaces with staghorn arrangement, and the absence of mitosis figures. Immunohistochemistry was performed in case 01 to assist in the diagnosis. Weak and diffuse immunostaining was observed for α-SMA and intense and diffuse immunopositivity for Bcl-2 and CD34. Based on histopathological and immunohistochemical features, a diagnosis of SFT was rendered in both cases. The low occurrence and nonspecific clinical features of oral SFT may make its clinical diagnosis difficult. Also, morphological and immunohistochemical are essential for differential diagnosis with other mesenchymal neoplasms.

Case report on aggressive central giant cell granuloma of mandible

Central giant cell granuloma (CGCG) is an uncommon, benign but aggressive osteolytic neoplasm of the craniomaxillofacial region, histologically characterized by an abundance of evenly distributed multinucleated giant cells within a sea of spindle-shaped mesenchymal stromal cells, scattered throughout the fibrovascular connective tissue stroma containing areas of hemorrhage. A rapid diagnostic assessment, together with an adequate histopathologic verification, is essential to improve the management and the prognosis of this locally destructive lesion. A rare case of a large destructive CGCG involving the entire right side of mandible, causing extensive bony resorption, and buccal, medial as well as inferior border cortical expansion, in a young female is presented. It was treated successfully by surgical excision under general anesthesia.

Digestive pseuodpolyposis as a form of presentation of digestive metastases of primary gastric leiomyosarcoma.

A 71-year-old male was diagnosed with gastric leiomyosarcoma in 2020 after biopsies of an ulcerated gastric lesion. Despite oncological treatment, he presented bone, liver and lung progression. Fourth line treatment with Pazopanib was started in 2022 with no evidence of intestinal or peritoneal metastases. He was attended in the Emergency Department in February 2023 due to symptoms of gastrointestinal bleeding with clinical and analytical repercussion with hemoglobin 5.8g/dl. Initially he presented hematemesis and subsequently hematochezia. An upper and lower endoscopic study was performed, revealing multiple sessile polypoid lesions with an irregular mucosal pattern of between 5-30 mm distributed throughout all explored sections at the gastric, duodenal and colic mucosal; some of them ulcerated with fibrin deposits on the surface and signs of recent hemostasis. The histological study demonstrated infiltration by spindle-shaped mesenchymal cells with atypical nuclei, a Ki-67 proliferation index >80%, and an immunohistochemical profile consistent with digestive metastases of primary gastric leiomyosarcoma. CT scan was performed confirming tumor progression with pulmonary, digestive, hepatic, bone, muscle and peritoneal dissemination of gastric leiomyosarcoma.

AGGRESSIVE MANDIBULAR OSTEOLYTIC LESION IN A CHILD: A DIAGNOSIS CHALLENGE AND MANAGEMENT

Benign osteolytic lesions are common in children and include true neoplasms and tumor-like lesions. A 7-year-old female patient presented with swelling in the left hemiface with 3 months of evolution. Facial asymmetry and mouth opening limitation were observed on extraoral examination. Intraorally, the lesion had a normal color and firm consistency. Computed tomography revealed an osteolytic isodense lesion in the left posterior mandible and zygomatic arch. The patient's medical history was not contributory. The diagnosis of incisional biopsy was suggestive of ossifying fibroma with osteosarcoma-like areas. The patient underwent resection of the lesion and rehabilitation. Microscopically, the surgical specimen showed proliferation of multinucleated giant cells and ovoid to spindle-shaped mononuclear mesenchymal cells as well as immature bone trabeculae exhibiting osteocytes and osteoblastic pavimentation, both atypical, in connective tissue with variables density. The final diagnosis was central giant cell granuloma. The patient has been followed up, showing no signs of local complications. Benign osteolytic lesions are common in children and include true neoplasms and tumor-like lesions. A 7-year-old female patient presented with swelling in the left hemiface with 3 months of evolution. Facial asymmetry and mouth opening limitation were observed on extraoral examination. Intraorally, the lesion had a normal color and firm consistency. Computed tomography revealed an osteolytic isodense lesion in the left posterior mandible and zygomatic arch. The patient's medical history was not contributory. The diagnosis of incisional biopsy was suggestive of ossifying fibroma with osteosarcoma-like areas. The patient underwent resection of the lesion and rehabilitation. Microscopically, the surgical specimen showed proliferation of multinucleated giant cells and ovoid to spindle-shaped mononuclear mesenchymal cells as well as immature bone trabeculae exhibiting osteocytes and osteoblastic pavimentation, both atypical, in connective tissue with variables density. The final diagnosis was central giant cell granuloma. The patient has been followed up, showing no signs of local complications.

PERIPHERAL GIANT CELL LESION ASSOCIATED WITH PERIPHERAL OSSIFYING FIBROMA: A RARE CASE REPORT

Lesions formed by the combination of microscopic aspects of peripheral giant cell lesion (PGCL) and peripheral ossifying fibroma (POF) are rare. Whether they represent true hybrid lesions or part of a disease spectrum is debatable. A 38-year-old woman was referred for evaluation of a painless, slow-growing swelling on the mandible that had been identified 6 months earlier. Intraoral examination revealed a pinkish nodule with whitish, erythematous, and ulcerated areas located on the buccal gingiva of teeth #37 and #38. Computed tomography revealed hyperdense foci in the lesion and erosion of the underlying bone cortex. Under the diagnostic hypothesis of POF, an excisional biopsy was performed. Histopathologic analysis revealed proliferation of oval to spindle-shaped mononucleated mesenchymal cells, interspersed with multinucleated giant cells. Extensive deposition of trabecular bone intermixed by cellular fibroblastic tissue could also be observed. The definitive diagnosis was PGCL associated with POF. The patient remains under close follow-up. Lesions formed by the combination of microscopic aspects of peripheral giant cell lesion (PGCL) and peripheral ossifying fibroma (POF) are rare. Whether they represent true hybrid lesions or part of a disease spectrum is debatable. A 38-year-old woman was referred for evaluation of a painless, slow-growing swelling on the mandible that had been identified 6 months earlier. Intraoral examination revealed a pinkish nodule with whitish, erythematous, and ulcerated areas located on the buccal gingiva of teeth #37 and #38. Computed tomography revealed hyperdense foci in the lesion and erosion of the underlying bone cortex. Under the diagnostic hypothesis of POF, an excisional biopsy was performed. Histopathologic analysis revealed proliferation of oval to spindle-shaped mononucleated mesenchymal cells, interspersed with multinucleated giant cells. Extensive deposition of trabecular bone intermixed by cellular fibroblastic tissue could also be observed. The definitive diagnosis was PGCL associated with POF. The patient remains under close follow-up.

A case of ovarian carcinosarcoma composed of endometrioid carcinoma and endometrial stromal sarcoma

Ovarian carcinosarcoma (OCS) is a rare malignancy accounting for only 1‒4% of all ovarian cancers. A 44-year-old premenopausal woman presented at the Obstetrics and Gynecology Department of the University Hospital of Saga, with the chief complaint of sudden abdominal pain. Tumor markers present in her serum were cancer antigen (CA) 19-9 (103U/mL), and CA 125 (114U/mL). Transvaginal ultrasound examination showed a complex mass (74×71×67mm) with solid and cystic components in the left abdominal area. Abdominopelvic computed tomography images showed a polycystic mass with a long diameter of 94 mm in the left adnexal area. The patient underwent a laparotomy immediately after the appropriate evaluation of examinations, leading to total abdominal hysterectomy, bilateral salpingo-oophorectomy and partial omentectomy. Due to the emergency surgery, intraoperative histological diagnosis for ovarian tumor was not performed. The preoperative evaluation of radiological imaging revealed no evidence of lymph node swelling, therefore lymph node resection was omitted. The left ovarian tumor already showed a partial rupture. Pathological examination following surgery revealed tubular and solid growth of the epithelial component and fascicular growth of spindle-shaped mesenchymal cells. Immunohistochemistry identified the epithelial component as endometrioid carcinoma (EC) and the mesenchymal component as endometrial stromal sarcoma (ESS). Endometriotic tissue was attached to the malignant tumor. The patient was successfully treated with adjuvant chemotherapy (paclitaxel plus carboplatin) after surgery. The patient is still alive without recurrence at 9 months after surgery. Considering the rarity of OCS with EC and ESS, we present an overview of the literature and discuss several histological and clinical issues. The etiology and pathogenesis of such tumors require further investigation (words; 228).

Repair of rat cranial bone defect by using amniotic fluid-derived mesenchymal stem cells in polycaprolactone fibrous scaffolds and platelet-rich plasma

Introduction: Tissue regenerative medicine strategies, as a promising alternative has become of major interest to the reconstruction of critical size bone defects. This study evaluated the effects of the simultaneous application of polycaprolactone (PCL), amniotic fluid mesenchymal stem cells (AF-MSCs) and platelet-rich plasma (PRP) on the repair of rat cranial bone defects. Methods: The AF-MSCs were isolated at the end of the second week of pregnancy in rats. PRP obtained from rat blood and the random PCL fibrous scaffolds were prepared using the electrospinning method. Circular full thickness (5 mm) bone defects were developed on both sides of the parietal bones (animal number=24) and the scaffolds containing AF-MSCs and PRP were implanted in the right lesions. Thereafter, after eight weeks the histological and immunohistochemistry studies were performed to evaluate the bone formation and collagen type I expression. Results: The spindle-shaped mesenchymal stem cells were isolated and the electron microscope images indicated the preparation of a random PCL scaffold. Immunohistochemical findings showed that collagen type I was expressed by AF-MSCs cultured on the scaffold. The results of hematoxylin and eosin (H&E) staining indicated the formation of blood vessels in the presence of PRP. Additionally, immunofluorescence findings suggested that PRP had a positive effect on collagen type I expression. Conclusion: The simultaneous application of fibrous scaffold + AF-MSCs + PRP has positive effects on bone regeneration. This study showed that PRP can affect the formation of new blood vessels in the scaffold transplanted in the bone defect.

Chondromesenchymal hamartomas in a 24-year-old male mimicking a posterior mediastinal tumor and a 5-month-old boy with postoperative disseminated intravascular coagulation: two case reports

BackgroundChondromesenchymal hamartoma of the chest wall is a rare, benign disease that usually presents at birth or in early infancy. It typically involves one or more ribs, forming a unilateral or bilateral extrapleural mass. Patients may be asymptomatic or complain of mild respiratory distress depending on tumor size and location. To the best of our knowledge, only two of the approximately 100 cases reported so far are adults.Case presentationWe present two cases of chondromesenchymal hamartoma. The first case involved the left fifth rib in a 24-year-old male, in close proximity to the fifth vertebral body in the left posterior mediastinum, mimicking a posterior mediastinal tumor on imaging. The tumor was excised via thoracoscopy and the patient had an uneventful postoperative course. The second case was that of a 5-month-old boy, who had a tumor involving the left fifth and sixth ribs which caused thoracic cage collapse. Following en bloc resection of the tumor and the involved rib segments, the patient was transferred to the intensive care unit for treatment of pulmonary infection and disseminated intravascular coagulation (DIC). He was discharged from the hospital in stable condition 11 days later. On histopathology, the tumor was found to be a chondromesenchymal hamartoma with immature spindle-shaped mesenchymal cells, plate-like hyaline cartilage, areas of woven bone formation, endochondral ossification and calcification, osteoclastic giant cells, and secondary aneurysmal bone cysts.ConclusionsAlthough the presently reported cases have morphological characteristics similar to previously reported ones, they had distinct radiological and clinical characteristics. Patient 1 is only the third report of an adult with chondromesenchymal hamartoma. His case was characterized by its radiological appearance mimicking a posterior mediastinal tumor. Patient 2 represents the first documentation of DIC as a postoperative complication following excision of a chondromesenchymal hamartoma. We present these two cases to provide clinicopathological insights regarding this extremely rare tumor that are relevant to both pathologists and clinicians.

DESMOPLASTIC FIBROMA OF THE MANDIBLE: A DIAGNOSTIC CHALLENGE

Desmoplastic fibroma (DF) is a rare benign myofibroblastic tumor with a locally aggressive behavior and high recurrence rate. We describe a case of DF in a 27-year-old woman presenting a painful, soft exophytic lesion on the mandible with approximately 7 months of evolution. Panoramic radiograph showed a radiolucent unilocular lesion with sclerotic borders involving teeth 44, 45, and 47. Clinical diagnosis was ossifying fibroma, and incisional biopsy was performed. Histopathologic analysis revealed a neoplasm characterized by proliferation of round, ovoid, and spindle-shaped mesenchymal cells with indistinct borders and no atypia. Intense deposition of collagen fibers, interspersed with areas of low-to-moderate cellularity, were also found. Neoplastic cells showed immunopositivity for α–smooth muscle actin, S-100, synaptophysin, neuron-specific enolase, and Ki-67 but no immunoexpression of desmin. The patient was referred for tumor excision. This case reinforces the importance of associating clinical, radiographic, histopathologic, and immunohistochemical findings for the correct diagnosis and management of DF.

Undifferentiated myxoid lipoblastoma with PLAG1 gene rearrangement in infant

ObjectivesTo analyze the clinicopathologic feature, diagnosis and differential diagnosis of undifferentiated myxoid lipoblastoma in infant. MethodsThe study included 2 cases of undifferentiated myxoid lipoblastoma in infant according to the molecular genetic diagnosis. The relevant clinicopathologic feature was investigated. ResultsWe describe 2 cases of undifferentiated myxoid lipoblastoma in infant. The both large circumscribed masses are located in deep soft tissue. Unlike most lipoblastoma, lobulated appearance was not obvious in one case and completely absent in another. The both cases presented prominent myxoid change with a plexiform vascular pattern. There were some spindle-shaped or stellate mesenchymal cells, while no any mature adipocytes. The initial suggestion of case 1 was myxoid liposarcoma, and case 2 was aggressive angiomyxoma. However, few S-100 positive lipoblasts suggested the origin of the tumor. FISH analysis using a PLAG1 break apart probe confirmed a PLAG1 rearrangment. The final diagnosis was undifferentiated myxoid lipoblastoma. ConclusionsThe undifferentiated myxoid lipoblastoma is a very rare tumor in infant. Histologically, prominent myxoid change, a plexiform vascular pattern and lacking of mature adipocytes make it indistinguishable from myxoid liposarcoma, PMMTI and aggressive angiomyxoma. The S-100 positive lipoblasts and genetic rearrangement of PLAG1 helps in confirming the diagnosis. Even if there were no mature adipocytes, myxoid lipoblastoma was still a diagnosis that can not be ignored in myxoid tumors in children.

Management of Central Giant Cell Granulomas of the Jaws: An Unusual Case Report with Critical Appraisal of Existing Literature.

Central giant cell granuloma (CGCG) is an uncommon, benign but aggressive osteolytic neoplasm of the craniomaxillofacial region, histologically characterized by an abundance of evenly distributed multinucleated giant cells within a sea of spindle-shaped mesenchymal stromal cells, scattered throughout the fibrovascular connective tissue stroma containing areas of hemorrhage. A rapid diagnostic assessment, together with an adequate histopathologic verification, is essential to improve the management and the prognosis of this locally destructive lesion. A rare case of a large destructive CGCG involving the entire right angle of mandible, causing extensive bony resorption, and buccal, medial as well as inferior border cortical expansion with multiple perforations, in a young child is presented. It was treated successfully by enucleation and aggressive curettage followed by peripheral ostectomy preserving the continuity of the mandible. Two adjunctive measures were employed; first, chemical cauterization of the residual bony walls to prevent possible recurrence, for which this tumor is notorious, and second, placement of fresh autologous platelet-rich fibrin within the bony defect to hasten bone fill and reossification, thus obviating the need for a bone graft.

Invasiveness-triggered state transition in malignant melanoma cells.

Cancer cells are considered to have high morphological heterogeneity in human melanoma tissue. Here, we report that epithelial cancer cells are dominant in different development stages of human melanoma tissues. The cellular and molecular mechanisms that maintain melanoma cells in the epithelial state are further investigated in the A2058 cell line. We find that micropore (8 µm) transwell invasion, but not superficial migration in the scratch assay, can induce remarkable morphological changes between epithelial and mesenchymal melanoma cells within 4 days. The morphological switch is associated with dynamic changes of epithelial-mesenchymal transition (EMT) hallmarks E-cadherin and vimentin. Further immunoflurencent staining and co-immunoprecipitation assay showed the uncoupling of the M3 muscarinic acetylcholine receptor (mAChR) and the p75 neurotrophin receptor (p75NTR) in epithelial melanoma cells. Specific knockdown of M3 mAChR by small interfering RNA (siRNA) significantly abrogates the transition of spindle-shaped mesenchymal cells to epithelial cells. Collectively, we report a cellular model of invasiveness-triggered state transition (ITST) in which melanoma cell invasion can induce morphological changes between epithelial and mesenchymal cells. ITST is one of the biological basis for maintaining metastatic melanoma cells in the epithelial state. Furthermore, M3 mAChR receptor-mediated ITST provides a novel therapeutic strategy to inhibit the development ofmalignant melanoma.

Myolipoma associated with hyperadrenocorticism and diabetes mellitus in a female poodle

ABSTRACT: This report provides an unpublished account of an intra-abdominal myolipoma in a 11-year-old female Poodle with hyperadrenocorticism and diabetes mellitus. The patient was well controlled for both endocrine diseases; however, was suffering for severe abdominal discomfort. Ultrasound scan revealed a huge abdominal mass. At necropsy a pinkish mass (35cm x 28cm x 12cm) of elastic consistency attached to the broad ligament of the left uterine horn was reported. Histologically, this mass was constituted of a mixed population of well-differentiated adipocytes and of spindle-shaped mesenchymal cells. Both tumor cells were positive for vimentin at immunohistochemistry, while the spindle-shaped cells were positive for desmin and actin, compatible with smooth muscle cells. Immunohistochemistry was crucial for myolipoma characterization.

Potential Role of microRNA-183 as a Tumor Suppressor in Hepatocellular Carcinoma

Background/Aims: Disseminated tumors, known as metastases, are responsible for ninety-percent of mortality due to cancer. Epithelial to mesenchymal transition, a phenomenon required for morphological conversion of non-motile discoid shaped epithelial cells to highly motile spindle-shaped mesenchymal cells, is thought to be a pre-requisite for metastatic progression. Metastasis-associated 1 (MTA1) protein is a prime inducer of EMT and metastatic progression in all solid tumors including hepatocellular carcinoma (HCC). However, the molecular mechanisms that regulate the expression and function of MTA1 in HCC have not been elucidated. Methods: In silico prediction algorithms were used to find microRNAs (miRNAs) that may target MTA1. We examined the relationship between the expression of MTA1 and miR-183 using quantitative real time PCR. We also determined the levels of the MTA1 protein using immunohistochemistry. Reporter assays, in the presence and absence of the miR-183 mimic, were used to confirm MTA1 as a bona fide target of miR183. The effect of miR-183 on HCC pathogenesis was determined using a combination of in vitro migration and invasion assay, together with in vivo xenograft experiments. The correlation between miR-183 and MTA1 expression was also studied in samples from HCC patients, and in The Cancer Genome Atlas dataset. Results: Analysis of the sequence database revealed that MTA1 is a putative target of miR-183. MTA1 protein and RNA expression showed opposite trends to miR-183 expression in breast, renal, prostate, and testicular tissue samples from cancer patients, and in the metastatic HCC cell line HepG2. An inverse correlation was also observed between MTA1 (high) and miR-183 (low) expression within samples from HHC patients and in the TCGA dataset. Reporter assays in HepG2 cells showed that miR-183 could inhibit translation of a reporter harboring the wild-type, but not the mutant miR-183 3’-untranslated region (UTR). In addition, miR-183 significantly inhibited in vitro migration and invasion in HepG2 cells, and in vivo hepatic metastasis. Conclusion: Our results reveal a novel post-transcriptional regulatory mechanism for MTA1 expression via miR-183, which is suppressed during HCC pathogenesis.

Inflammatory myofibroblastic tumors of the lung carrying a chimeric A2M-ALK gene: report of 2 infantile cases and review of the differential diagnosis of infantile pulmonary lesions

We report 2 infantile cases of pulmonary tumor carrying a chimeric A2M-ALK gene. A2M-ALK is a newly identified anaplastic lymphoma kinase (ALK)-related chimeric gene from a tumor diagnosed as fetal lung interstitial tumor (FLIT). FLIT is a recently recognized infantile pulmonary lesion defined as a mass-like lesion that morphologically resembles the fetal lung. Grossly, FLIT characteristically appears as a well-circumscribed spongy mass, whereas the tumors in these patients were solid and firm. Histologically, the tumors showed intrapulmonary lesions composed of densely proliferating polygonal or spindle-shaped mesenchymal cells with diffuse and dense infiltrations of inflammatory cells forming microcystic or micropapillary structures lined by thyroid transcription factor 1-positive pneumocytes, favoring inflammatory myofibroblastic tumor rather than FLIT. The proliferating cells were immunoreactive for ALK, and A2M-ALK was identified in both tumors with reverse-transcription polymerase chain reaction. The dense infiltration of inflammatory cells, immunoreactivity for ALK, and identification of an ALK-related chimeric gene suggested a diagnosis of inflammatory myofibroblastic tumor. Histologically, most reported FLITs show sparse inflammatory infiltrates and a relatively low density of interstitial cells in the septa, although prominent infiltration of inflammatory cells and high cellularity of interstitial cells are seen in some FLITs. The present cases suggest that ALK rearrangements, including the chimeric A2M-ALK gene, may be present in these infantile pulmonary lesions, especially those with inflammatory cell infiltration. We propose that these infantile pulmonary lesions containing a chimeric A2M-ALK gene be categorized as a specific type of inflammatory myofibroblastic tumor that develops exclusively in neonates and infants.

Pathological Features and Pathogenesis of the Endomyocardial Form of Restrictive Cardiomyopathy in Cats

SummaryThis study reports pathological and molecular features in 41 cases of feline restrictive cardiomyopathy (RCM). Grossly, there were patchy or diffuse areas of endocardial thickening affecting the left ventricle. The more common patchy endocardial lesions occurred as large trabecular or irregular broad bands of fibrous tissue bridging the left ventricular free wall and ventricular septum. Microscopically, regardless of the gross pattern, the thickened endocardium contained various numbers of stellate, spindle-shaped or elongated mesenchymal cells surrounded by fibrous connective tissue. Immunohistochemical findings were indicative of smooth muscle differentiation in mesenchymal cells. These cells proliferated vigorously and produced alcian blue-positive ground substance and collagen fibres; it was considered that the mesenchymal cells contributed to the formation of the endocardial lesions. In addition, multiple left ventricular ‘false tendons’ were invariably included within the trabecular or broad fibrous bands, providing a framework for formation of those bands. Evidence of endocarditis or endomyocarditis was lacking in all 41 cases, and no viral genomes were detected in any of the DNA or RNA samples obtained from 14 of the hearts. These observations suggest that any relationship between feline RCM and a virus-induced inflammatory response seems unlikely.

Report of rare case of dermatofibrosarcoma protuberans in the buccal mucosa: review of diagnostic, histopathological and immunohistochemical criteria

Dermatofibrosarcoma protuberans (DFSP) is an uncommon intermediate-grade soft tissue sarcoma. The tumor is found preferentially on the trunk, whereas the head and neck region are affected in only 10% to 15% of cases. We report the case of a 44-year-old woman with a 5-month history of an asymptomatic, firm, yellow nodule in the mucosa of the right cheek measuring 2.5 cm. The clinical diagnosis was lipoma and an excisional biopsy was obtained. Histopathological analysis revealed a proliferation of spindle-shaped mesenchymal cells arranged in interlacing fascicles amidst fibrous stroma. Low mitotic activity (2 mitoses per field) and deep cell infiltration into adipose tissue were observed. These features led to the histopathological diagnosis of a malignant low-grade mesenchymal cell tumor. Immunohistochemical analysis revealed negative staining for α-SMA, S-100, and Bcl-2, but positive staining for Ki-67 (18%) and strong and diffuse staining for CD34. These findings were compatible with the diagnosis of DFSP. Only two cases of DFSP in the oral cavity, both involving the cheek mucosa, have been described so far, highlighting the rarity of the present case.