Myxoma of the penis in an African pygmy hedgehog (Atelerix albiventris).

A penile tumor (4 × 2.5 × 1 cm) was surgically removed from an African pygmy hedgehog (Atelerix albiventris) aged 3 years and 5 months. The tumor was continuous with the dorsal fascia of the penile head. Histopathologically, tumor cells were pleomorphic (oval-, short spindle- and star-shaped cells) with low cell density. Abundant edematous stroma was weakly positive for Alcian blue staining and positive for colloidal iron reaction. Tumor cells displayed no cellular atypia or karyokinesis. Tumor cell cytoplasm was positive for vimentin antibody, while cytoplasm and nuclei were positive for S-100 protein antibody. Tumor cell ultrastructure matched that of fibroblasts, and the rough endoplasmic reticulum was enlarged. The tumor was diagnosed as myxoma. This represents the first report of myxoma in a hedgehog.

Cardiac myxoma with glandular differentiation: an immunohistochemical and ultrastructural study.

A case of cardiac myxoma with glandular differentiation is reported. The patient did not have elements of the Carney triad or syndrome. The tumor was mainly composed of characteristic stellate cells in a focally collagenized, myxoid stroma, along with aggregates of glandular-forming epithelial cells, with mucin-containing intra- and intercellular lumina. Ultrastructurally, these gland spaces displayed short, straight microvilli and junctional complexes. The epithelial cells were positive for cytokeratin 7 and negative for cytokeratin 20. Calretinin was positive in the stellate cells and negative in the epithelial component. The potential origin from pluripotent mesenchymal cells or from seeded stem cells is hypothesized for glandular differentiation in myxomas. Further studies are required to unravel the relationship between stellate cells and the diverse heterologous components reported in these tumors.

Clinico-radiographic examination of odontogenic myxoma with displacement of unerupted upper third molar: review of the literature / Examen clínico-radiográfico de un mixoma odontogénico con desplazamiento de un tercer molar no erupcionado: revisión de la literatura

Odotogenic myxoma is a benign tumor which presents in 3 percent to 6 percent of all odontogenic tumors. According to the WHO classification, multiple radiolucent areas of varying size, separated by straight or curved bony septa with poorly defined borders are the radiologic characteristics of the condition. We report the case of maxillary odontogenic myxoma in a 21 year old man. The radiological feature of the current case was interesting, due to the size of the lesion and severe displacement of the upper third molar.

El mixoma odontogénico es un tumor benigno que se presenta en el 3 por ciento a 6 por ciento de todos los tumores odontogénicos. De acuerdo a la clasificación de la OMS, las características radiológicas de esta patología presentan múltiples áreas radiolúcidas de tamaño variable, separadas por tabiques óseos rectos o curvos, con márgenes mal definidos. Presentamos un caso de mixoma odontogénico maxilar en un hombre de 21 años. La característica radiológica es interesante, debido al tamaño de la lesión y al desplazamiento severo del tercer molar superior.

A novel kind of tumor type-characteristic junction: plakophilin-2 as a major protein of adherens junctions in cardiac myxomata.

Using novel antibodies of high avidity to--and specificity for--the constitutive desmosomal plaque protein, plakophilin-2 (Pkp2), in a systematic study of the molecular composition of junctions connecting the cells of soft tissue tumors, we have discovered with immunocytochemical, biochemical and electron microscopical methods, a novel type of adherens junctions in all 32 cardiac myxomata examined. These junctions contain cadherin-11 as their major transmembrane glycoprotein, which we could repeatedly show in colocalization with N-cadherin, anchored in a cytoplasmic plaque formed by α- and ß-catenin, together with the further armadillo-type proteins plakoglobin, p120, p0071 and ARVCF. Surprisingly, all adherens junctions of these tumors contained, in addition, another major armadillo protein Pkp2, hitherto known as an obligatory and characteristic constituent of desmosomes in epithelium-derived tumors. We have not detected Pkp2 in a series of noncardiac myxomata studied in parallel. Therefore, we conclude that this acquisition of Pkp2, which we have recently also observed in some mesenchymally derived cells growing in culture, can also occur in tumorigenic transformations in situ. We propose to examine the marker value of Pkp2 in clinical diagnoses of cardiac myxomata and to develop Pkp2-targeted therapeutic reagents.

Retropharyngeal superficial angiomyxoma.

OBJECTIVE: To describe the first published case of superficial angiomyxoma with an epithelial component occurring in the retropharynx. METHOD: Case report of a patient with swallowing difficulties caused by a rare case of superficial angiomyxoma in the retropharynx. RESULTS: Superficial angiomyxoma is a distinct entity among the dermal myxomatous lesions. Superficial angiomyxoma is poorly circumscribed, and local recurrence is common unless the tumour is excised with clear margins. Distinctive histological features include a myxoid mass composed of spindle and stellate-shaped cells and occasional multinucleated cells. There is prominent vasculature and a mixed inflammatory infiltrate in the stroma, particularly by neutrophil polymorphs. Epithelial structures are seen in about one-third of cases. A case of retropharyngeal tumour with morphological features of superficial angiomyxoma is reported. The tumour cells, including multinucleated ones, were negative for soft tissue differentiation markers. The inflammatory cells included lymphocytes, histiocytes and neutrophil polymorphs. CONCLUSION: This case demonstrates that a cutaneous type of angiomyxoma with epithelial-lined structures can occur in deep soft tissue, such as the retropharynx.

Myxomatous neoplasms in the perineal region of baboons.

BACKGROUND: In baboons, Papio sp. neoplasms tend to affect the hematopoietic system most commonly, with rare documentation of myxomatous neoplasms. In contrast, women can develop myxomatous masses within deep peripelvic tissues with some frequency during their reproductive years. METHODS: We have identified and examined, retrospectively, myxomatous perineal masses in twelve female baboons within one research facility and compared their histopathologic, immunohistochemical and electron microscopic features to their human variants. RESULTS: Our results indicate that these myxomatous neoplasms, in humans and non-human primates, share common features. CONCLUSION: Further research, particularly molecular genetic analysis, may be needed to identify the baboon as a true animal model for myxomatous perineal neoplasms.

Cardiac myxoma cells exhibit embryonic endocardial stem cell features.

The origin of myxoma, the most frequent tumour of the heart, remains uncertain. Previous phenotypic characterizations have shown heterogeneous results and the most recent hypothesis suggests that cardiac myxoma originates from a primitive pluripotential cardiogenic cell. We investigated the expression of actin isoforms in 30 left atrial myxomas by immunohistochemistry and in eight consecutive tumours by RT-PCR. alpha-Smooth muscle actin (alpha-SMA) protein and/or transcripts were detected in all cases, whereas alpha-cardiac actin was observed in few cases and alpha-skeletal actin was always absent. Besides classical features, vessel-like structures were characterized by cells expressing CD34 and, less frequently, alpha-SMA. Confocal microscopy showed focal co-expression of CD34 and alpha-SMA in myxoma cells, suggesting a gradual loss of stem endothelial markers and the acquisition of myocytic antigens. In order to confirm this hypothesis, early cardiac differentiation markers were also investigated. RT-PCR documented the presence of transcripts for Sox9 (100%), Notch1 (87.5%), NFATc1 (37.5%), Smad6, metalloproteinases 1 and 2 alone or in variable combinations and the absence of ErbB3 and WT1. Myxoma cells maintained phenotypic heterogeneity in vitro, including the expression of alpha-SMA and the presence of stress fibres. These findings document in cardiac myxoma cells phenotypic markers of the embryonic endothelial-to-mesenchymal transformation that precedes terminal differentiation of endocardial cushions, supporting the hypothesis that cardiac myxoma cells may derive from adult developmental remnants.

Left atrial myxoma in transplanted heart.

Primary cardiac tumours are discovered in about 1 in 2000 necropsies. Cardiac myxomas make up half of all benign intracardiac tumours. Seventy five per cent are located in the left atrium. The first left atrial myxoma arising from the left atrium of a transplanted heart is reported.

[Heart myxoma histogenesis in the light of its histological and ultrastructural features]. / Predstavleniia o gistogeneze miksomy serdtsa v svete ee gistologicheskikh i ul'trastrukturnykh osobennostei.

In 168 cases of heart myxoma histological and electron-microscopic examination have revealed signs of embryonal endothelium capable of vasoformation and glycoprotein and glycosaminoglycanes synthesis in myxoma cells. Neither differentiation of myxomas cells up to mature endotheliocytes no signs of malignant transformation was found. According to the authors, heart myxoma is a true benign dysontogenetic tumor originating from embryonal endothelium. The term myxoma does not reflect morphological entity of the tumor and the authors suggest to call it embryonal endocardial endothelioma.

Cardiac sarcoma showing bone formation and neurogenic markers: report of a case.

A 54 year-old Japanese female with cardiac insufficiency was found to have a left atrial mass and smaller masses on the mitral valve. Excisional surgery of the masses and mitral valve replacement were carried out. In spite of intensive post-operative radiation therapy, the patient died of intra-atrial recurrence and brain metastases after 8 months. Tumour cells were spindled to oval, were positive for vimentin, S100 protein and neurone specific enolase. Laminin and fibronectin were also demonstrated. Bone formation and myxoid areas were present. An ultrastructurally identifiable stromal component, possibly responsible for laminin and fibronectin staining, was also present. The merits of the two main diagnostic possibilities - a mesenchymal/fibroblastic sarcoma showing bone and aberrant S100 protein, and a malignant peripheral nerve sheath tumour with bone - were discussed. In practical terms, the tumour was given the diagnosis of unclassifiable sarcoma of the left atrium. Atrial sarcomas showing neural markers and bone formation are exceedingly rare, and this report adds a further exceptionally uncommon case to the literature.

Myxoid dermatofibroma.

AIMS: This report presents seven cases of a rare variant of dermatofibroma, characterized by marked mucinous stromal changes. METHODS AND RESULTS: In this retrospective clinicopathological study, lesions preferentially occurred on the lower extremities of young to middle-aged females. Clinical (differential) diagnoses included: dermatofibroma (two cases), cyst, tophus, ganglion and neurofibroma. Histology revealed well circumscribed, faintly stained dermal to subcutaneous lesions which contained abundant stromal mucin. A variable amount of spindle-shaped cells, occasional lymphocytes and fine collagen fibres were also seen. Epidermal hyperplasia above as well as storiform arrangement of spindle cells and some sclerotic collagen at the periphery of the lesion indicated the fibrohistiocytic origin. Individual histopathological features included: bizarre giant cells, perifollicular arrangement and seas of mucin with pseudovascular clefts in one case each. Immunohistochemically, all lesions were positive for KiM1p (> 50% of the cells). Moreover, two lesions showed moderate reactivity for factor XIIIa (10-25%), one each with NK1C3 (> 90%) and smooth muscle actin (50%), but were otherwise negative with a broad panel of markers. Electron microscopy in one case revealed large pools of mucin interspersed by a moderate number of fibrocytes with fine fibrillary collagen. CONCLUSION: This series confirms myxoid dermatofibroma as a rare variant of fibrohistiocytic tissue response; our series also indicates that many of these lesions might be misinterpreted as cutaneous myxoma.

Ultrastructure abnormalities in proteoglycans, collagen fibrils, and elastic fibers in normal and myxomatous mitral valve chordae tendineae.

Normal and myxomatous chordae tendineae were studied using light and electron microscopy, to assess the alterations in the appearance and mutual arrangement of proteoglycans, collagen fibrils, and elastic fibers. Specific staining with ruthenium red and cuprolinic blue in a critical electrolyte concentration mode were used to localize proteoglycans. Fresh tissues were fixed in glutaraldehyde containing the cationic dyes and embedded into Spurr resin. Semithin sections of LR White (London Resin Co., Basingstoke, U.K.)-embedded tissue were used for histochemistry. In normal chordae tendineae, the fibrosa comprised close-packed collagen fibrils intermixed with elastic fibers. These were surrounded by a thin layer of elastic fibers and collagen fibrils, both of which were closely associated with proteoglycans. In myxomatous chordae tendineae, alterations were observed in the connective tissue. Proteoglycans were more abundant and were distributed throughout the tissue. The outermost layer was transformed into an undifferentiated electron-dense mass surrounding the central fibrosa, which contained degraded elastic fibers and collagen fibrils. Collagen fibrils had faint banding or lacked a banding pattern altogether. Spaces between collagen fibrils were occupied by abnormal proteoglycans or proteoglycan aggregates. Elastic fibers showed varying degrees of degeneration and were occasionally replaced by electron-lucent spaces containing microfibrils. Accumulation of abnormal proteoglycan was also observed around degenerated elastic fibres and collagen fibrils.

Don't confuse dental soft tissues with odontogenic tumors.

Surgical pathologists are cautioned against the misinterpretation of immature dental tissues (dental papillae and follicles) and dental pulp as odontogenic tumors, especially odontogenic myxomas and fibromas. The close histologic similarity of the immature tissues to tumors may require a clinical-radiologic correlation with the histopathologic specimen in order to distinguish the locally aggressive tumors from innocuous dental tissues.

Multiple cutaneous myxomas. Report of a case without other elements of Carney's complex.

An 11-year-old hispanic female was referred for evaluation of multiple asymptomatic papules which had slowly developed since age two. The patient had no significant medical history and no family members, including an older sibling, were similarly affected. Physical examination revealed multiple 2-6 mm flesh-colored to erythematous papules over the posterior scalp, trunk, and extremities, predominantly in a midline distribution. No lentigines, blue nevi, or evidence of endocrine ab-normalities were noted. Echocardiogram was normal with no evidence of myxoma. Six cutaneous biopsies showed myxomas, as evidenced by well-circumscribed dermal tumors composed of stellate, dendritic cells embedded in a mucinous stroma. Special stains and electron microscopy confirmed the H&E finding. Immunoperoxidase staining for Factor XIIIa was positive in the dendritic tumor cells, suggesting a relationship with dermal dendrocytes. This patient represents a case of multiple cutaneous myxomas without other components of Carney's complex of myxomas, spotty pigmentation, endocrine overactivity, and a variety of uncommon tumors. A long-term follow-up is indicated since some of the above cited elements of the syndrome could appear over time.

Angiomyofibroblastoma of the vulva: a clinicopathologic study of seven cases.

A clinicopathologic and immunohistochemical review was made of seven cases of angiomyofibroblastoma. The patients were middle-aged women who had a slowly growing mass, measuring 1.5-6 cm in maximum dimension, located subcutaneously in the vulva. The tumors were well-demarcated and characterized by well-vascularized, alternating hypercellular and hypocellular edematous areas composed of bland, plump spindle- or oval-shaped stromal cells frequently aggregated around small blood vessels. An epithelioid appearance of the stromal cells was seen in two cases. Immunohistochemically, the stromal cells were consistently positive for vimentin and desmin, but negative for muscle specific actin, alpha-smooth muscle actin, myosin, cytokeratins, S-100 protein or von Willebrand factor. Ultrastructurally, the plump stromal cells had a small amount of peripherally located rough endoplasmic reticulum, numerous pinocytotic vesicles and abundant intermediate filaments, on which immunogold probes for desmin were localized, whereas fine filaments were few and there were no electron dense plaques. Thus, while the proliferating stromal cells expressed an immunohistochemical profile of peculiar myoid differentiation, ultrastructural findings differed from those of smooth muscle cells or those seen in typical myofibroblasts. At 1-4 years after surgery, there was no evidence of recurrence.

[Glandular myxoma of the heart]. / Glandularis myxoma szívben.

Light microscopic, immunohistochemical and ultrastructural studies were performed on a surgically removed left atrial myxoma containing glandular structures. Routine examination showed glandular lumina lined by cylindric epithelium in the characteristic myoxoid stroma, and the glands contained PAS positive mucin. The glandular structures demonstrated significant positivity for wide-spectrum-CK, EMA, and moderate positivity for CEA. Stromal cells were positive for vimentin, FVIII. Ag was present only in surface cells and blood vessels. Ultrastructurally the gland showed characteristics of mucin secreting epithelium. The authors briefly overview the currently existing theories about the histogenesis of myxomas.

Ultrastructural spectrum of cutaneous nerve sheath myxoma/cellular neurothekeoma.

The histogenesis of cutaneous nerve sheath myxoma (NSM)/cellular neurothekeoma (CNT) is still controversial. In this study, we examined the ultrastructural features of 16 NSM (3 classical, 11 CNT, and 2 mixed NSM/CNT). We classified the cells into 4 groups ultrastructurally. Type I cells were undifferentiated polygonal cells with ovoid nuclei, cytoplasmic microfilaments, and occassionally with microfilament-associated dense bodies. In most cells, the cytoplasmic membrane showed focal membranous densities and occasional basal-lamina-like material. This cell type comprised approximately 90% of CNT. Type II cells were more differentiated, had ovoid or spindled shapes, were rich in intracytoplasmic filaments, and were surrounded by continuous basal lamina. These cells were consistent with Schwann cells and were present in the classical and mixed forms of NSM, and in a single case of CNT. Type III cells had features of perineurial cells and were relatively rare in classical NSM. Type IV cells resembled fibroblasts and were encountered in all variants of NSM. These results support the view that 1) the classical NSM has neural (mainly Schwann cell) differentiation, 2) CNT is predominantly composed of undifferentiated cells with partial features of Schwann cells, smooth muscle cells, myofibroblasts and fibroblasts, suggesting a divergent differentiation, and 3) CNT and NSM represent a histologic spectrum, but in CNT, the neural features are not fully expressed.

Angiomyofibroblastoma of the vulva.

Angiomyofibroblastoma is a rare, myxoid tumor of the vulva. To date only 12 cases have been reported in the world literature. Patients are usually premenopausal and present with a vulval mass initially diagnosed as a Bartholin's cyst. The lesions are well circumscribed and range from 0.5 to 12 cm in size. Microscopically the tumors are characterized by high cellularity, numerous blood vessels, and plump stromal cells. Treatment is by surgical excision. There are currently no published reports of local recurrence or metastatic disease. Angiomyofibroblastoma should be differentiated from other neoplasms of the vulva where radical surgical treatment is indicated. A Case Report of angiomyofibroblastoma of the periclitoral region diagnosed in a postmenopausal woman is presented.

Aggressive angiomyxoma of the vulva: an unusual, deceptive and recurrence-prone tumour with evidence of estrogen receptor expression. Case report.

Positive staining for estrogen receptors is reported in a new case of aggressive angiomyxoma of the vulva. Clinical, light- and electron microscopic features as well as immunohistochemical reactions in this case are compared with the 28 earlier published cases, and the main differential diagnosis, angiomyofibroblastoma of the vulva, is discussed.