Primary pulmonary myxoid sarcoma in the interlobar fissure of the left lung lobe: a case report.

BACKGROUND: Primary pulmonary myxoid sarcoma (PPMS) is a rare, low-grade malignant tumor, constituting approximately 0.2% of all lung tumors. Despite its rarity, PPMS possesses distinctive histological features and molecular alterations, notably the presence of EWSR1-CREB1 gene fusion. However, its precise tissue origin remains elusive, posing challenges in clinical diagnosis. CASE DEMONSTRATION: A 20-year-old male patient underwent a routine physical examination 6 months prior, revealing a pulmonary mass. Following surgical excision, microscopic evaluation unveiled predominantly short spindle-shaped tumor cells organized in a fascicular, beam-like, or reticular pattern. The stromal matrix exhibited abundant mucin, accompanied by lymphocytic and plasma cell infiltration, with Russell bodies evident in focal areas. Immunophenotypic profiling revealed positive expression of vimentin and epithelial membrane antigen in tumor cells, whereas smooth muscle actin and S-100, among others, were negative. Ki-67 proliferation index was approximately 5%. Subsequent second-generation sequencing identified the characteristic EWSR1-CREB1 gene fusion. The definitive pathological diagnosis established PPMS. The patient underwent no adjuvant chemotherapy or radiotherapy and remained recurrence-free during a 30-month follow-up period. CONCLUSIONS: We report a rare case of PPMS located within the left lung lobe interlobar fissure, featuring Russell body formation within the tumor stroma, a novel finding in PPMS. Furthermore, the histomorphological characteristics of this case highlight the diagnostic challenge it poses, as it may mimic inflammatory myofibroblastic tumor, extraskeletal myxoid chondrosarcoma, or hemangiopericytoma-like fibrous histiocytoma. Therefore, accurate diagnosis necessitates an integrated approach involving morphological, immunohistochemical, and molecular analyses.

Sclerosing epithelioid fibrosarcoma of bone with hybrid features: clinicopathologic, radiologic, and molecular analysis of three cases.

Sclerosing epithelioid fibrosarcoma (SEF) occurring as a primary bone tumor is exceptionally uncommon. Even more rare are cases of SEF that show morphologic overlap with low-grade fibromyxoid sarcoma (LGFMS). Such hybrid lesions arising within the bone have only rarely been reported in the literature. Due to their variegated histomorphology and non-specific radiologic features, these tumors may pose diagnostic difficulties. Herein we describe three molecularly confirmed primary bone cases of sclerosing epithelioid fibrosarcoma that demonstrated prominent areas showing the features of LGFMS and with areas resembling so-called hyalinizing spindle cell tumor with giant rosettes (HSCTGR). Two patients were female and one was male aged 26, 47, and 16, respectively. The tumors occurred in the femoral head, clavicle, and temporal bone. Imaging studies demonstrated relatively well-circumscribed radiolucent bone lesions with enhancement on MRI. Cortical breakthrough and soft tissue extension were present in one case. Histologically the tumors all demonstrated hyalinized areas with SEF-like morphology as well as spindled and myxoid areas with LGFMS-like morphology. Two cases demonstrated focal areas with rosette-like architecture as seen in HSCTGR. The tumors were all positive for MUC4 by immunohistochemistry and cytogenetics, fluorescence in-situ hybridization, and next-generation sequencing studies identified EWSR1 gene rearrangements confirming the diagnosis in all three cases.Hybrid SEF is exceedingly rare as a primary bone tumor and can be difficult to distinguish from other low-grade spindled and epithelioid lesions of bone. MUC4 positivity and identification of underlying EWSR1 gene rearrangements help support this diagnosis and exclude other tumor types.

Obstructive cardiac myxosarcoma of the right ventricular outflow tract with pulmonary embolism and concurrent right atrial hemangiosarcoma in a dog.

A 13-year-old spayed female rottweiler crossbreed dog was presented with an 8-day history of abnormal gait and collapse associated with excitement or physical activity. A cardiac gallop was noticed on thoracic auscultation, and a 1st-degree atrioventricular block and sinus tachycardia were noted on an electrocardiogram. Echocardiography identified a hypoechoic, irregularly marginated luminal mass in the right ventricle at the level of the pulmonic valves. Postmortem gross examination confirmed the presence of a soft, polypoid, and botryoid mass (9 × 3 × 3 cm) with a smooth and glistening surface attached to the endocardium of the right ventricular outflow tract and extending to the pulmonary artery. The histological findings were consistent with the diagnosis of myxosarcoma with pulmonary embolism. In addition, the dog in this report had a right atrial hemangiosarcoma and a cutaneous hemangioma unrelated to her clinical findings. Key clinical message: Cardiac myxosarcomas are very rare neoplasms in dogs and concomitant primary heart tumors of different histogenesis are even rarer in dogs. To the authors' knowledge, this is the first report of coexistent myxosarcoma and hemangiosarcoma in the heart of a dog. Cardiac myxosarcomas should be considered in the differential diagnosis of intracavitary heart masses associated with signs of cardiac obstruction and failure.

Myxosarcome cardiaque obstructif de la voie d'éjection du ventricule droit avec embolie pulmonaire et hémangiosarcome auriculaire droit concomitant chez un chien. Une chienne croisée rottweiler stérilisée âgée de 13 ans a été présentée avec une histoire de démarche anormale et d'effondrement associés à l'excitation ou à l'activité physique depuis 8 jours. Un galop cardiaque a été noté à l'auscultation thoracique, un bloc auriculo-ventriculaire du 1er degré et une tachycardie sinusale ont été notés à l'électrocardiogramme. L'échocardiographie a permis d'identifier une masse luminale hypoéchogène et irrégulièrement marginalisée dans le ventricule droit au niveau des valvules pulmonaires. L'examen macroscopique post-mortem a confirmé la présence d'une masse molle, polypoïde et botryoïde (9 × 3 × 3 cm) avec une surface lisse et brillante attachée à l'endocarde de la voie d'éjection du ventricule droit et s'étendant jusqu'à l'artère pulmonaire. Les résultats histologiques concordaient avec le diagnostic de myxosarcome avec embolie pulmonaire. De plus, la chienne dans ce rapport présentait un hémangiosarcome auriculaire droit et un hémangiome cutané sans rapport avec ses résultats cliniques.Message clinique clé :Les myxosarcomes cardiaques sont des néoplasmes très rares chez le chien et les tumeurs cardiaques primaires concomitantes d'histogenèse différente sont encore plus rares chez le chien. À la connaissance des auteurs, il s'agit du premier rapport de myxosarcome et d'hémangiosarcome coexistant dans le cœur d'un chien. Les myxosarcomes cardiaques doivent être pris en compte dans le diagnostic différentiel des masses cardiaques intracavitaires associées à des signes d'obstruction et d'insuffisance cardiaque.(Traduit par Dr Serge Messier).

A cardiac malignant primary tumor: Left atrium myxosarcoma-A case report.

Myxosarcoma only accounts for a very small proportion of primary malignant tumors of the heart. The disease has no specificity in clinical manifestations or features on medical images. In this case study, we report about a middle-aged female patient afflicted with cardiac myxosarcoma. The initial transthoracic echocardiography of the patient revealed a cardiac myxoma. However, the postoperative histopathology confirmed the presence of a malignant cardiac myxosarcoma. Post-surgery follow-up imaging examinations revealed local recurrence in the left atrium as well as soft-tissue and bone metastases. The recurrent tumor and metastases were subsequently treated with chemotherapy and radiotherapy. However, the tumor did not respond to treatment and the disease progressed.

T-regulatory cells predict clinical outcome in soft tissue sarcoma patients: a clinico-pathological study.

BACKGROUND: Soft tissue sarcomas (STS) are generally considered non-immunogenic, although specific subtypes respond to immunotherapy. Antitumour response within the tumour microenvironment relies on a balance between inhibitory and activating signals for tumour-infiltrating lymphocytes (TILs). This study analysed TILs and immune checkpoint molecules in STS, and assessed their prognostic impact regarding local recurrence (LR), distant metastasis (DM), and overall survival (OS). METHODS: One-hundred and ninety-two surgically treated STS patients (median age: 63.5 years; 103 males [53.6%]) were retrospectively included. Tissue microarrays were constructed, immunohistochemistry for PD-1, PD-L1, FOXP3, CD3, CD4, and CD8 performed, and staining assessed with multispectral imaging. TIL phenotype abundance and immune checkpoint markers were correlated with clinical and outcome parameters (LR, DM, and OS). RESULTS: Significant differences between histology and all immune checkpoint markers except for FOXP3+ and CD3-PD-L1+ cell subpopulations were found. Higher levels of PD-L1, PD-1, and any TIL phenotype were found in myxofibrosarcoma as compared to leiomyosarcoma (all p < 0.05). The presence of regulatory T cells (Tregs) was associated with increased LR risk (p = 0.006), irrespective of margins. Other TILs or immune checkpoint markers had no significant impact on outcome parameters. CONCLUSIONS: TIL and immune checkpoint marker levels are most abundant in myxofibrosarcoma. High Treg levels are independently associated with increased LR risk, irrespective of margins.

A clinicopathologic examination of myxofibrosarcoma. Do surgical margins significantly affect local recurrence rates in this infiltrative sarcoma subtype?

BACKGROUND AND OBJECTIVES: Myxofibrosarcoma (MFS) is an aggressive soft tissue tumor with an unpredictable recurrence pattern. We sought to (a) determine whether margin status in MFS is correlated to rates of local recurrence (LR) and (b) identify demographic and treatment variables associated with disease-related outcomes in this population. METHODS: This retrospective study identified 42 surgically treated patients with MFS over 10 years at a single institution. Patient demographics, tumor characteristics, intraoperative variables, and disease-related outcomes were recorded. RESULTS: Thirty-three (83%) patients had negative surgical margins and seven (18%) had positive margins. Four of 32 patients (13%) with negative margins developed subsequent LR compared to six of seven (86%) patients with positive margins (p < .001). Three patients (75%) with metastatic disease were deceased at the end of the study, while five (15%) without metastasis were deceased (p = .024). CONCLUSIONS: Positive margin procedures for MFS were associated with LR. However, negative surgical margins demonstrated a relatively high rate of LR compared to other soft tissue sarcoma subtypes. Furthermore, though MFS tends to locally recur and have a propensity for distant metastasis, patients are observed to have a higher probability of death from other causes.

Deep sequencing of myxoinflammatory fibroblastic sarcoma.

Myxoinflammatory fibroblastic sarcoma (MIFS) has recurrent genetic features in the form of a translocation t(1;10)(p22-31;q24-25), BRAF gene fusions, and/or an amplicon in 3p11-12 including the VGLL3 gene. The breakpoints on chromosomes 1 and 10 in the t(1;10) cluster in or near the TGFBR3 and OGA genes, respectively. We here used a combination of deep sequencing of the genome (WGS), captured sequences (Cap-seq), and transcriptome (RNA-seq) and genomic arrays to investigate the molecular outcome of the t(1;10) and the VGLL3 amplicon, as well as to assess the spectrum of other recurrent genomic features in MIFS. Apart from a ROBO1-BRAF chimera in a t(1;10)-negative MIFS-like tumor, no fusion gene was found at RNA-seq. This was in line with WGS and Cap-seq results, revealing variable breakpoints in chromosomes 1 and 10 and genomic breakpoints that should not yield functional fusion transcripts. The most common genomic rearrangements were breakpoints in or around the OGA, NPM3, and FGF8 genes in chromosome band 10q24, and loss of 1p11-p21 and 10q26-qter (all simultaneously present in 6/7 MIFS); a breakpoint in or near TGFBR3 in chromosome 1 was found in four of these tumors. Amplification and overexpression of VGLL3 was a consistent feature in MIFS and MIFS-like tumors with amplicons in 3p11-12. The significant molecular genetic outcome of the recurrent t(1;10) could be loss of genetic material from 1p and 10q. Other recurrent genomic imbalances in MIFS, such as homozygous loss of CDKN2A and 3p- and 13q-deletions, are shared with other sarcomas, suggesting overlapping pathogenetic pathways.

Neuropathogenicity of newly isolated avian leukosis viruses from chickens with osteopetrosis and mesenchymal neoplasms.

ABSTRACT The prototype fowl glioma-inducing virus (FGVp) causes fowl glioma and cerebellar hypoplasia in chickens. In this study, we investigated whether a strain of avian leukosis virus (ALV), associated with avian osteopetrosis and mesenchymal neoplasms, is able to induce fowl glioma. We encountered avian osteopetrosis and mesenchymal neoplasms, including myxosarcoma and rhabdomyosarcoma, in Japanese native chickens used for both egg-laying and meat production. These birds were also affected by non-suppurative encephalitis and glioma in their brains. Four ALV strains (GifN_001, GifN_002, GifN_004, GifN_005) were isolated, and a phylogenic analysis of envSU showed that these isolates were classified into different clusters from FGVp and the variants previously reported. Whereas the envSU shared a high identity (94.7%) with that of Rous sarcoma virus (strain Schmidt-Ruppin B) (RSV-SRB), the identity between envTM of GifN_001 and that of FGVp was high (94.5%), indicating that GifN_strains may emerge by recombination between FGVp and other exogenous ALVs. Specific-pathogen-free chickens inoculated in ovo with GifN_001 revealed fowl glioma and cerebellar hypoplasia. These results suggest that the newly isolated strains have acquired neuropathogenicity to chickens.

Myxosarcoma Associated with the Kidney in a Cat: Case Report.

A 12 yr old spayed female domestic shorthair with a history of lethargy, anorexia, and a pendulous abdomen was referred after a cranial abdominal mass was palpated on physical examination. Thoracic radiographs and an abdominal ultrasound revealed a mass associated with the kidney and moderate hemoperitoneum. Exploratory laparotomy revealed abdominal hemorrhage originating from a right renal mass that was adhered to the caudal vena cava. Following a right nephrectomy, histopathology diagnosed the mass as a perirenal/renal myxosarcoma. Based upon thoracic radiographs and abdominal ultrasound, the patient remains disease free at 14 mo postoperatively.

Canine myxosarcomas, a retrospective analysis of 32 dogs (2003-2018).

BACKGROUND: Myxosarcomas are known to be classified as soft tissue sarcomas. However, there is limited clinical characterization pertaining specifically to canine cutaneous myxosarcomas in the literature. The objective of this study is to evaluate the local recurrence rate, metastatic rate and prognosis of canine myxosarcoma. RESULTS: A total of 32 dogs diagnosed with myxosarcoma via histopathology were included in this retrospective study. All dogs had surgical resection. No adjunct treatments were performed in 9 dogs, while 22 dogs also received either radiation therapy or chemotherapy, or a combination of both. One dog received only NSAID after surgery. Overall median survival time (MST) was 730 days (range 20-2345 days). The MST of dogs with a tumor mitotic count < 10/10 HPF was 1393 days (range 20-2345 days). The dogs with a tumor mitotic count of 10 or greater/10 HPF had a MST of 433 days (range 169-831 days). There was no significant difference of MST among different treatment modalities. Local recurrence was noted in 13 cases (40.6%) and the median time to recurrence was 115.5 days (range 50-1610 days). The median time to local recurrence in dogs with mitotic count of < 10/10 HPF was 339 days (range 68-1610 days) and in dogs with mitotic count of 10 or greater/10 HPF was 119 days (range 50-378). Metastasis to local lymph node or lung was noted in 8 cases (25%) with median time to metastasis of 158.5 days (range 0-643 days). CONCLUSIONS: Based on the results of this retrospective study, myxosarcoma may have a higher local recurrence rate and risk of metastasis to the local lymph nodes compared to other soft tissue sarcomas.

Radiomic features from MRI distinguish myxomas from myxofibrosarcomas.

BACKGROUND: Myxoid tumors pose diagnostic challenges for radiologists and pathologists. All myxoid tumors can be differentiated from each other using fluorescent in-situ hybridization (FISH) or immunohistochemical markers, except for myxomas and myxofibrosarcomas. Myxomas and myxofibrosarcomas are rare tumors. Myxomas are benign and histologically bland, whereas myxofibrosarcomas are malignant and histologically heterogenous. Because of the histological heterogeneity, low grade myxofibrosarcomas may be mistaken for myxomas on core needle biopsies. We evaluated the performance of T1-weighted signal intensity (T1SI), tumor volume, and radiomic features extracted from magnetic resonance imaging (MRI) to differentiate myxomas from myxofibrosarcomas. METHODS: The MRIs of 56 patients (29 with myxomas, 27 with myxofibrosarcomas) were analyzed. We extracted 89 radiomic features. Random forests based classifiers using the T1SI, volume features, and radiomic features were used to differentiate myxomas from myxofibrosarcomas. The classifiers were validated using a leave-one-out cross-validation. The performances of the classifiers were then compared. RESULTS: Myxomas had lower normalized T1SI than myxofibrosaromas (p = 0.006) and the AUC using the T1SI was 0.713. However, the classification model using radiomic features had an AUC of 0.885 (accuracy = 0.839, sensitivity = 0.852, specificity = 0.828), and outperformed the classification models using T1SI (AUC = 0.713) and tumor volume (AUC = 0.838). The classification model using radiomic features was significantly better than the classifier using T1SI values (p = 0.039). CONCLUSIONS: Myxofibrosarcomas are on average higher in T1-weighted signal intensity than myxomas. Myxofibrosarcomas are larger and have shape differences compared to myxomas. Radiomic features performed best for differentiating myxomas from myxofibrosarcomas compared to T1-weighted signal intensity and tumor volume features.

Upper extremity myxofibrosarcoma mimicking an erosive inflammatory arthritis: a case report.

Myxofibrosarcoma is a malignant fibroblastic soft tissue neoplasm containing a variable amount of myxoid stroma that commonly presents as a slow-growing mass in elderly patients. The neoplasm may be superficial or deep to the muscle fascia and characteristically has an infiltrative growth pattern with a dominant or multinodular mass. We describe an unusual case of high-grade myxofibrosarcoma of the wrist and forearm that infiltrated the muscles, tendons, and wrist joint, causing bone erosions. The tumor was mistakenly diagnosed as synovitis and a chronic, erosive, inflammatory process. The diffuse nature, absence of a dominant mass, and radiographic appearance complicated the diagnosis. Although neoplasms of the synovial spaces are rare, this case demonstrates that tumors with a highly infiltrative growth pattern can mimic inflammatory synovitis and that neoplasms should be considered in the differential diagnosis when clinical and laboratory features are discordant with the imaging appearance.

Aggressive invasive recurrence of a right atrial myxofibrosarcoma.

A 58-year-old man presented with left-sided chest discomfort 9 years ago. At that time a 12-centimeter extrapleural mass was resected via left thoracotomy. Surgical pathology revealed a low-grade myxofibrosarcoma. Since that time, he had undergone three separate resections of recurrent left extrapleural masses with sternotomy and thoracotomy. He proceeded to have a five-year disease-free interval after which a pericardial mass invading into the right atrial free wall, the atrioventricular groove, and the right coronary artery was identified. Surgical resection was performed with negative margins and the right atrium and atrioventricular groove were reconstructed without any residual tricuspid regurgitation.

Expression of dog1 in low-grade fibromyxoid sarcoma: A study of 19 cases and review of the literature.

DOG1 is a highly-sensitive marker often included in the immunohistochemical panel for the diagnosis of gastrointestinal stromal tumors (GISTs). Recent research has shown that DOG1 may also be expressed by low-grade fibromyxoid sarcomas (LGFMSs); this may give rise to diagnostic error when the sarcoma is located in the abdominal cavity. This paper reports on immnohistochemical expression of DOG1 in 19 LGFMSs using two different monoclonal antibodies: K9 (Leica, Novocastra Laboratories, Newcastle upon Tyne, UK) and SP31 (Thermo Scientific, Freemont, USA). All LGFMSs displayed the standard histological pattern of alternating myxoid and fibrous areas, low cellularity and bland spindle-cell morphology. Positive staining for MUC4 was observed in 18/19 cases (94.7%), while there was rearrangement of the FUS gene in 14/19 (73.7%) cases and of the EWR1 gene in 2/19 (10.5%). The sarcoma staining negative for MUC4 displayed FUS gene rearrangement. Whole-section immunohistochemistry revealed positive staining for DOG1 in 8/19 cases (42.1%), though only with clone K9. Cytoplasmic as well as membrane staining was observed in all cases; staining was focal (10-30%) and of varying intensity (1+ to 2+). In conclusion, DOG1 clone K9 exhibited low sensitivity (42.1%) for the diagnosis of LGFMS, although higher than clone SP31. Since the two clones display similar sensitivity and specificity for GIST diagnosis, SP31 would appear to be more specific for this purpose, since no reaction was observed here with LGFMS, a GIST-mimicking lesion.

Soft tissue myxofibrosarcoma: A clinico-pathological analysis of a series of 75 patients with emphasis on the epithelioid variant.

BACKGROUND AND OBJECTIVES: The clinical course of soft tissue myxofibrosarcoma is characterized by a high incidence of recurrences and there is no agreement on how to identify patients at major risk. An epithelioid histological variant has been described, with a possible worse prognosis. We reviewed our series to identify prognostic factors and assess clinical significance of the epithelioid variant. METHODS: We examined the clinico-pathological features of a series of 75 patients affected by soft tissue myxofibrosarcoma at a mean follow-up of 63 months (range 17-132). RESULTS: Disease specific survival and local recurrence free survival were, respectively, 84.8% and 76.8% at 5 years. Seven patients (8.6%) presented with the epithelioid variant with a survival of 62.5%. High grade and epithelioid morphology were negative prognostic factors for patient survival, high grade, and inadequate surgical margins for local recurrence. Radiotherapy had a local protective effect in high grade tumors. CONCLUSIONS: Our experience confirms the difficulties in obtaining wide margins in myxofibrosarcoma and the high rate of recurrence. Local recurrences did not significantly affect survival and a limb-sparing approach can be chosen also in recurrences. Patients affected by the epithelioid variant showed a worse prognosis. Chemotherapy should be considered as adjuvant treatment in this subtype. J. Surg. Oncol. 2016;114:50-55. © 2016 Wiley Periodicals, Inc.

[Myxofibrosarcoma in the abdominal cavity]. / Myxofibrosarkom dutiny brisní.

A number of benign and malignant tumors may develop in the abdominal cavity. Sarcomas are rather rare tumors of the abdominal cavity. They are often diagnosed at advanced growth stages as their local growth can cause clinical problems to the patients. The author presents a case report of myxofibrosarcoma in the abdominal cavity.Key words: myxofibrosarcoma.

High-grade myxoinflammatory fibroblastic sarcoma: a report of 23 cases.

We describe 23 cases of high-grade myxoinflammatory fibroblastic sarcoma (MIFS). The patients were 15 women and 8 men, with the age ranging at the time of diagnosis from 39 to 93 years (mean, 64.3 years; median, 66 years). Follow-up was available for 18 patients, of whom 9 developed metastatic disease; 7 of these died. Most tumors showed a predilection for the soft tissues of the extremities, with 14 cases involving the lower limb and 5 the upper extremity. However, in both sites, the acral parts were affected in only 1 case each. Of the 4 remaining tumors, 2 were found in axilla, 1 was found in sacral area, and 1 developed in the scar on the breast, 14 years after previous excision of a mammary carcinoma and subsequent local irradiation. The tumor size ranged from 1.3 cm to as much as 30 cm in the largest dimension with a mean size of 8.3 cm. Histologically, the tumors were characterized by occurrence of 3 types of characteristic cells, including (1) lipoblast-like cells with an ample, distended, mucin-filled cytoplasm compartmentalized by a variable number of intracytoplasmic septa, thus remotely resembling soccer balls; (2) large, polygonal, bizarre ganglion-like cells similar to those seen in the Hodgkin disease, also called Reed-Sternberg-like cells. Within an ample, deeply eosinophilic cytoplasm, there was an oval nucleus with vesicular chromatin and a large, inclusion-like nucleolus. Binucleated, multinucleated, or more pleomorphic forms of these cells were also present; (3) cells with emperipolesis of variable sizes, ranging from very inconspicuous neoplastic cells containing only one to a few engulfed cells to conspicuous large ones having many inflammatory cells, usually polymorphonuclear leukocytes admixed with various numbers of some lymphoid cells, within the cytoplasm. Quite often, we found elements that combined the histologic features of all the above 3 characteristic tumor cell types. In 2 tumors, we found an additional undifferentiated spindle cell sarcoma component, whereas in another tumor, a chondrosarcomatous moiety was evident. For comparison, we studied 10 cases of pleomorphic hyalinizing angiectatic tumor (PHAT) of soft tissues. Based on the identification of morphological changes typical for MIFS within most of the cases of PHAT, we suggest that most cases of PHAT represent examples of MIFS merely having hyaline ectatic vessels.

Canine low-grade intra-orbital myxosarcoma: case report.

OBJECTIVE: The aim of this study was to evaluate important clinical, morphological, histopathological, histochemical, and immunohistochemical characteristics in order to establish the diagnosis and prognosis of a low-grade intra-orbital myxosarcoma. ANIMAL STUDIED: A mongrel dog presented a 2-year history of a neoplastic mass behind the right eye. RESULTS: The neoplasm presented a mesenchymal spindle and stellate cell proliferation with an abundant myxoid matrix, moderate anisocariosis, and a low mitotic index. It stained positive for vimentin, moderately positive for periodic acid-Schiff, and negative for Gomori trichrome stain and α-smooth muscle actin. CONCLUSIONS: One year following surgical excision, the patient remains disease free. The histological findings established a diagnosis of a rare canine intra-orbital low-grade myxosarcoma.

Metronomic Chemotherapy for Myxosarcoma Treatment in a Kori Bustard (Ardeotis kori).

A 22-year-old, wild-caught male kori bustard (Ardeotis kori) developed a large, slow-growing subcutaneous mass over the keel. The mass was surgically debulked and histopathologically described as a myxosarcoma. Surgical dehiscence and concurrent local tumor regrowth, with no evidence of metastasis, occurred over the subsequent 3 months, necessitating 2 additional surgical procedures to close the wound. At 19 weeks after the initial procedure, a second debulking surgical procedure was performed, at which time carboplatin-impregnated matrix beads were placed in the lesion. Moderate local tumor regrowth was clinically appreciable 4 weeks after surgery, at which time an oral metronomic chemotherapeutic protocol consisting of daily cyclophosphamide (10 mg/m(2)) and meloxicam (0.1 mg/kg) was initiated. Four months later, the tumor was no longer palpable. While oral therapy was discontinued during the breeding season, mass regrowth was observed, and the mass was surgically debulked before reinitiating oral chemotherapy. Treatment was extended for over 1 year with no hematologic evaluation or serum biochemical abnormalities, and the bird otherwise remained clinically healthy. To our knowledge, this is the first report of a myxosarcoma in a bustard species and the first report of successful clinical application of metronomic chemotherapy in an avian species.