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.

Charcot-Leyden crystals: do they exist in veterinary species? A case report and literature review.

The Charcot-Leyden crystal (CLC) is a major human eosinophil protein that readily crystallizes; these crystals are common in eosinophilic diseases. Although anecdotal existence of these crystals is known in veterinary pathology, definitive reports do not exist, to our knowledge. We identified eosinophilic crystals in a laryngeal myxosarcoma from a 2-y-old, spayed female, Labrador Retriever dog that were tentatively interpreted as CLCs. However, Ziehl-Neelsen acid-fast stain was negative, arguing against CLCs. The crystals stained red with Masson trichrome, precluding collagen. Periodic acid-Schiff and alcian blue were negative. The crystals stained positively with Okajima, and no myoglobin immunoreactivity was detected, supporting their identity as hemoglobin crystals. In the absence of a hematologic abnormality, these crystals were interpreted to be abnormal hemoglobin breakdown products. Protein sequence comparison was pursued to determine whether a protein similar to CLC exists in mammals. Only 3 nonhuman primate species, the Sumatran orangutan ( Pongo abelii), rhesus macaque ( Macaca mulatta), and cynomolgus monkey ( Macaca fascicularis), had a sequence similarity of >80%. Of the crystal-forming residues, 12 of 54 (22%) were different in the Sumatran orangutan and 15 of 54 (28%) were different in the Macaca spp., which may affect the crystallization process. The lack of reports of CLCs in nonhuman species and our results collectively suggest that CLCs are human-specific.

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.

Intrathoracic myxosarcoma in a dog.

A 3-year-old Labrador retriever dog was presented with pyrexia, dyspnoea and tachycardia. A pleural effusion was detected radiographically and ultrasonography showed pleural fluid with floating material. The fluid was drained, revealing a soft tissue mass adjacent to the left ventricle. The aspirated fluid had a proteinaceous and gelatinous appearance. Cytological examination revealed atypical mesenchymal cells in a dense eosinophilic background, interpreted as consistent with the presence of a matrix-secreting tumour, probably a myxosarcoma. Thoracoscopy confirmed the presence of the mass adjacent to the left ventricle, but showed additional smaller pleural masses. Microscopical and immunohistochemical evaluation of a biopsy sample from the mass supported the diagnosis of a myxosarcoma, which was further confirmed by transmission electron microscopy.

[Myxoinflammatory fibroblastic sarcoma: a clinicopathologic study of 6 cases with review of literature].

OBJECTIVE: To study the clinicopathologic features, immunophenotypes and differential diagnosis of myxoinflammatory fibroblastic sarcoma (MIFS). METHODS: The clinical and pathologic features of 6 cases of MIFS were analyzed. Immunohistochemical study was performed using the standard EnVision method. RESULTS: There were altogether 2 adult males and 4 adult females (median age = 47 years and mean age = 50 years). Three cases were located in the lower extremities, 2 in the upper limbs and 1 in the axillary region. Common presentation included slowly growing mass or swelling in the extremities, accompanied by mild pain or tenderness. Grossly, the tumor appeared multinodular and ranged from 2.5 cm to 4.6 cm in diameter (mean = 3.4 cm). Microscopically, there was a dense inflammatory infiltrate merging with hyaline and myxoid zones in various proportions. Spindle-shaped tumor cells were seen admixed with large atypical cells which distributed singly or in small clusters, amongst an inflammatory, hyaline or a myxoid background. These atypical cells had large nuclei and prominent nucleoli, resembling virocytes, Reed-Sternberg cells or ganglion cells. Mitotic figures were rarely identified. Extracellular mucin associated with scattered monovacuolated or multivacuolated lipoblast-like cells was noted. Immunohistochemically, these bizarre cells were consistently positive for vimentin, but negative for a panel of antibodies including LCA, CD15, CD30, CD34, CD68, S-100, HMB45, AE1/AE3, smooth muscle actin and desmin. Follow-up result was available in 4 cases; and 2 of them showed local recurrence after an incomplete excision. There was no evidence of distant metastasis. CONCLUSIONS: MISF is a low-grade sarcoma of fibroblastic differentiation. Awareness of the clinical and pathologic characteristics is helpful in arriving at the correct diagnosis and distinction from benign inflammatory fibromyxoid lesions.

Prognostic implication of ezrin overexpression in myxofibrosarcomas.

BACKGROUND: The bases of tumorigenesis, progression, and metastasis remain obscure in myxofibrosarcoma. As a member of ezrin-radixin-moesin family, ezrin acts as a link between the cell membrane and actin cytoskeleton to integrate cell adhesion-mediated signaling. It is implicated in tumor progression and metastatic dissemination, and it is associated with adverse outcomes in several cancer types, including pediatric sarcomas. METHODS: Ezrin immunostain could be assessed from tissue microarrays of 78 cases of primary localized myxofibrosarcomas and correlated with clinicopathological factors and patient survival. In two myxofibrosarcoma cell lines, ezrin mRNA expression was measured by real-time reverse transcriptase-polymerase chain reaction and the endogenous expression and activating phosphorylation of ezrin protein analyzed by Western blot test. RESULTS: Ezrin overexpression was significantly associated with remarkable tumor necrosis (P = 0.025), increased histological grades (P = 0.037), advanced American Joint Committee on Cancer stages (P = 0.034), and higher mitotic rate (P < 0.001). Importantly, ezrin overexpression independently predicted inferior metastasis-free survival (P = 0.012, risk ratio = 4.083) and disease-specific survival (P = 0.0337, risk ratio = 4.537). The mRNA and total protein of ezrin in various cells were comparable in the expression level. Despite variation in abundance, phosphorylated ezrin at threonine(567) was detectable in myxofibrosarcoma cell lines but not in fibroblasts. CONCLUSIONS: In primary myxofibrosarcomas, ezrin overexpression correlates with important prognostic elements and independently portends worse outcomes, highlighting the potential prognostic usefulness of ezrin in predicting tumor aggressiveness.

Flow cytometric analysis of DNA ploidy and S-phase fraction in primary localized myxofibrosarcoma: correlations with clinicopathological factors, Skp2 expression, and patient survival.

BACKGROUND: Histological assessment for prognostication of myxofibrosarcomas remains challenging. We previously reported independent prognostic value of Skp2, an oncoprotein promoting S-phase progression (Clin Cancer Res 2006;12:487-98). METHODS: We evaluated S-phase fraction (SPF) and ploidy of myxofibrosarcomas and the association between SPF and Skp2. Flow cytometric findings were analyzed for 75 cases and correlated with clinicopathological factors, Skp2 labeling index (LI), metastasis-free survival (MeFS), and overall survival (OS). RESULTS: Forty-seven and 28 cases were classified as diploid and nondiploid, respectively. High SPF (>or=20%) was detected in 32 of 61 interpretable cases. Skp2 overexpression (LI >or= 10%) was seen in 36 of 72 cases with scoring. Nondiploidy correlated with higher French Federation of Cancer Centers (FNCLCC) grades (P = .006), remarkable necrosis (P = .010), and Skp2 overexpression (P = .018). Noticeably, SPF was significantly related to Skp2 LI (P < .001, r = .458), FNCLCC grade, American Joint Committee on Cancer stage, and mitotic rate. Nondiploidy predicted shorter OS (P = .0045) and MeFS (P = .0489), whereas SPF >or= 20% was only associated with inferior MeFS (P = .0252). In multivariate analyses, nondiploidy independently correlated with both OS (P = .020, RR = 3.337) and MeFS (P = .013, RR = 5.780), together with Skp2 overexpression (P = .014 for OS; P = .017 for MeFS) and disease-positive margins (P = .004 for OS; P = .002 for MeFS). CONCLUSION: Skp2 promotes S-phase progression in myxofibrosarcomas. SPF provides no independent prognostic usefulness; it is probably overshadowed by Skp2. Nondiploidy adds another predictive value to Skp2 overexpression and disease-positive margins in prognostication.

Skp2 overexpression is highly representative of intrinsic biological aggressiveness and independently associated with poor prognosis in primary localized myxofibrosarcomas.

PURPOSE: Two SCF(Skp2) ubiquitin ligase-related proteins, Skp2 and cyclin-dependent kinase subunit 1 (Cks1), are involved in posttranscriptional degradation of p27(Kip1) tumor suppressor. We analyzed the prognostic utility of p27(Kip1) and its interacting cell cycle regulators in myxofibrosarcomas. EXPERIMENTAL DESIGN: Clinicopathologic features and tissue microarray-based immunohistochemical expression of p27(Kip1), Skp2, Cks1, cyclin E, cyclin A, Ki-67, and minichromosome maintenance protein 2 (Mcm2) were assessed in 70 primary myxofibrosarcomas and correlated with clinical outcomes. Skp2 mRNA expression and the relationship between Skp2 and p27(Kip1) proteins were examined in six cases by semiquantitative reverse transcription-PCR and Western blotting, respectively. RESULTS: High indices of Skp2 (> or =10%), cyclin A (> or =10%), and Mcm2 (> or =50%) were adverse prognosticators at the univariate level. Furthermore, co-overexpression of Skp2 and cyclin A identified highly lethal cases in the entire cohort [P < 0.0001 for disease-specific survival (DSS), P = 0.0004 for overall survival (OS)] and the lower-grade subset (Fédération Nationale des Centres de Lutte Contre le Cancer grade 1 and 2; P = 0.0006 for DSS, P = 0.0093 for OS). In multivariate analyses, Skp2 overexpression overshadowed most intrinsic clinicopathologic factors and independently correlated with worse metastasis-free survival (P = 0.0012), DSS (P = 0.0234), and OS (P = 0.0056). Notably, positive margins independently predicted inferior local recurrence-free survival (P = 0.0012) and also negatively affected metastasis-free survival (P = 0.0471), DSS (P = 0.0152), and OS (P = 0.0173). Reverse transcription-PCR showed up-regulation of Skp2 mRNA in four cases and Western blotting displayed a matched expression pattern of Skp2. CONCLUSIONS: Margin status and intrinsic property of myxofibrosarcomas both affect patient survival. Skp2 overexpression is highly representative of the biological aggressiveness of myxofibrosarcomas and plays an important prognostic role.

Myxoinflammatory fibroblastic sarcoma of the neck.

BACKGROUND: Myxoinflammatory fibroblastic sarcoma (MIFS), also named inflammatory myxohyaline tumor of distal extremities with virocyte or Reed-Sternberg cells, is a rare tumor typically presenting as a painless mass in the extremities. PATIENTS: We present an unusual case of MIFS presenting as a subcutaneous neck mass. This is the first reported case of MIFS presenting in the neck. RESULTS: Therefore, this lesion must be considered in the differential diagnosis for painless subcutaneous masses presenting not only in the distal extremities, but also in the neck. CONCLUSION: MIFS has only recently been recognized. The differential diagnosis for MIFS is broad, and it can often be mistaken for several different inflammatory and neoplastic processes, which may require different treatment.

Myxosarcoma of the right ventricle: an immunohistochemical and ultrastructural study.

BACKGROUND: Myxosarcoma is an unusual form of primary cardiac malignancy with few reports in the literature. Although these tumours occur in a similar anatomical distribution to cardiac myxoma, the relationship between these two tumours is uncertain due largely to the limited studies available that characterise the morphological features of myxosarcoma. MATERIALS AND METHODS: The clinical and pathological features, including immunohistochemical and ultrastructural studies of cardiac myxosarcoma, in a 58-year-old male who died eight months after onset of symptoms are reported. RESULTS: At presentation the tumour was sited in the right ventricle and at post-mortem was found to have extended into the right atrium, pulmonary infundibulum, pulmonary artery, pericardium and pleural cavities. Histologically the tumour was composed of spindle and stellate cells within a myxoid stroma. Ultrastructural studies showed abundant intermediate filaments and vacuoles within the tumour cell cytoplasm, without any evidence of muscle differentiation. Immunohistochemical staining for vimentin and myoglobin was positive, while there was negative expression of desmin, smooth muscle actin, factor VIIIa, CD34, CD68, S-100 protein, bcl-2 and for epithelial markers. CONCLUSION: Comparison of the morphological findings from the present case with the limited data available suggests that myxosarcoma is not a single tumour entity but a group of tumours of diverse histogenesis.

Cardiac myxoma and myxosarcoma: clinical experience and immunohistochemistry.

From January 1978 to February 1999, 120 patients (42 males and 78 females) with cardiac myxoma (115) or myxosarcoma (5) underwent surgical excision or biopsy. There were 5 early postoperative deaths (mortality, 4.2%). Seventy-three survivors were followed up for 0.75 to 20.25 years (mean, 9.42 years); they comprised 4 myxosarcoma patients who all had recurrence or metastasis, and 69 myxoma patients who had no evidence of recurrence or metastasis. Neither familial myxoma nor Carney complex was found. The 5 cases of myxosarcoma and 18 randomly selected cases of myxoma were evaluated for proliferative activity, metastatic potential, and oncogene products by immunohistochemistry. The expression of p53 and Bcl-2 was similar in both groups. Overexpression of proliferating cell nuclear antigen and low expression of nm23 in myxosarcoma are consistent with the high rate of recurrence and metastasis of this tumor. Surgical resection of sporadic myxoma is a safe and effective treatment with satisfactory early and long-term results. However, the prognosis of myxosarcoma is still disappointing. Regular echocardiography and chest radiography or computed tomography are necessary for early detection of recurrence or metastasis of myxosarcoma.

Myxoid synovial sarcoma: an underappreciated morphologic subset.

Focal myxoid change is a well-recognized feature of synovial sarcoma, but the presence of a predominantly myxoid stroma is rare. We describe seven cases of myxoid synovial sarcoma in which marked myxoid change initially obscured the diagnosis, leading to confusion (principally with malignant peripheral nerve sheath tumor). The median age (20 yr) and tumor location (four lower extremity, two upper extremity, and one head and neck region) were similar to those found in typical synovial sarcoma. Histologically, five cases were monophasic spindle cell lesions with a lacy appearance in areas with a prominent Alcian blue-positive myxoid stroma. Each case had foci with more typical features of synovial sarcoma, including a fascicular growth pattern with a variably collagenized stroma, stromal mast cells, a hemangiopericytoma-like vascular pattern, and calcification. Two cases showed small foci of glandular (biphasic) differentiation. Immunohistochemically, all of the seven cases were positive for epithelial membrane antigen, four of six were positive for pan-keratin, three of six were positive for S-100, two of four were positive for CD99, and six of six were negative for desmin. Clinical follow-up in six cases ranged from 8 to 48 months (median, 21 mo). Local recurrence developed in three patients at 9, 20, and 24 months, respectively. In one of these three patients, lung metastases developed at 13 months, and the patient died of disseminated disease at 23 months. In another of the three patients, lung metastases developed at 27 months. Three patients had no evidence of disease at 8, 15, and 15 months. Our data are too limited to indicate any clinical differences between myxoid synovial sarcoma and conventional synovial sarcoma Recognition of this rare histologic variant of synovial sarcoma is important because it can easily be mistaken for other myxoid spindle cell neoplasms, potentially resulting in suboptimal therapy.