[Low-grade fibromyxoid sarcoma: analysis of 8 cases].

The diagnosis of low-grade fibromyxoid sarcoma was made in 8 patients. The lesions were 2-17 cm in the lower extremities and trunk. One patient had a long history of painless subcutaneous and intramuscular mass (median 1 year). All tumors showed predominantly the typical hypocellularity and cytologic features of typical low-grade fibromyxoid sarcoma; however, the areas of hypercellularity and nuclear enlargement and hyperchromatism were identified. No necrosis and mitotic activity less than 2 mf/50 HPF were present. Ultrastructurally, the tumor composed of neoplastic fibroblasts. No other cell differentiation was identified. Immunohistochemically, the neoplastic cells showed a positive response to vimentin and fibroblast antigen; no muscle-specific antigens were revealed. The Ki-67 labeling index with MIB-1 ranged 2-6%.

Pleomorphic rhabdomyosarcoma with pulmonary metastasis in a stranded Steller (northern) sea lion (Eumetopias jubatus).

A Steller (northern) sea lion (SSL), stranded in northern California in July 2000 had an anaplastic pleomorphic rhabdomyosarcoma in the latissimus dorsi muscle, with pulmonary metastasis. Diagnosis was based on light and electron microscopy and immunohistochemistry. Death was attributed to multiple parasitic and bacterial lesions. The SSL is of special concern because, for unknown reasons, the global population has declined by 50% over the last decade. Published post-mortem data, however, are scarce. This case report highlights several disease conditions that affect this species and is the first report of a malignant neoplasm in a free-ranging SSL.

Epithelioid variant of pleomorphic liposarcoma: a comparative immunohistochemical and ultrastructural analysis of six cases with emphasis on overlapping features with epithelial malignancies.

Pleomorphic liposarcoma (PL) is the least common subtype of liposarcoma, displaying a lipoblastic, malignant fibrous histiocytoma (MFH)-like and, less frequently, an epithelioid growth pattern. The epithelioid morphology in PL is still underrecognized and may closely simulate other epithelial neoplasms, mainly adrenal cortical carcinoma (ACC). No electron microscopic (EM) studies of the epithelioid variant of PL have been previously described, nor have there been studies of its immunoreactivity with A103 or alpha-inhibin. The purpose of this study is to analyze the histological, immunohistochemical, and EM features of epithelioid PL in an attempt to better explore the distinction from their epithelial mimickers, such as ACC. A panel of 5 antibodies was studied, including A103, alpha-inhibin, smooth muscle actin (SMA), AE1/AE3, and Cam 5.2. Out of 22 cases of PLs, 6 cases characterized by the presence of both epithelioid phenotype and pleomorphic lipoblasts were identified from the EM archives. There were 4 females and 2 males, with a mean age of 58 (range, 39-78). Two lesions arose in the thigh and 1 each in the abdominal wall, chest wall, anterior mediastinum, and retroperitoneum, with tumor size ranging from 7 to 17 cm (mean, 13 cm). Histologically, 2 PLs were pure epithelioid, whereas the other 4 had a mixed epithelioid and MFH-like appearance. Immunohistochemically, A103 (4/6), SMA (4/6), and AE1/AE3 (1/6) revealed a various degree of positive reactions. No immunolabeling for alpha-inhibin or Cam5.2 was detected in any case. By EM, the epithelioid areas revealed round or polyhedral cells with lipid droplets of various sizes and number, intimately apposed cell surfaces, occasional junction-like structures (4/6), and micropinocytotic vesicles (4/6). Interestingly, the ribosome-lamellar complexes, once thought to be characteristic of hairy cell leukemia but rarely seen in solid tumors, were noted in one pure epithelioid PL. When compared to the MFH-like area, rough endoplasmic reticula (RER) were less well developed, but mitochondria were more prominent in the epithelioid components. Neither mitochondria with tubulovesicular cristae nor prominent smooth endoplasmic reticula indicative of ACC were seen. Well-formed external lamina was not present. Other features to support a higher level of epithelial differentiation, such as lumen formation, microvilli, and tonofilaments, were not found. In conclusion, focal A103 reactivity in epithelioid undifferentiated tumors should be interpreted with caution before rendering the diagnosis of a primary or metastatic ACC, especially when examining biopsy specimens. The possibility of an epithelioid variant of PL must be excluded; alpha-inhibin can serve as a useful adjunct in this regard. In addition to variable intracytoplasmic fat droplets, the distinctive ultrastructural features of epithelioid variant of PL include numerous mitochondria, pinocytotic vesicles, junction-like structures, and, rarely, ribosome-lamellar complex. Despite some overlapping features, electron microscopy remains a useful tool to distinguish between epithelioid PL and ACC.

Clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres: a novel member of the perivascular epithelioid clear cell family of tumors with a predilection for children and young adults.

The perivascular epithelioid cell family of tumors (PEComas), defined by their co-expression of melanocytic and muscle markers, includes angiomyolipoma, lymphangioleiomyoma, and clear cell "sugar" tumors of the lung, pancreas, and uterus. We present seven cases of a unique and previously unrecognized tumor of children and young adults, which represents a new addition to the PEComa group of tumors. Culled from three institutions over a 50-year period, all cases occurred in or immediately adjacent to the ligamentum teres and falciform ligament. Six patients were female and one male; their ages ranged from 3 to 21 years (median, 11 yrs). Tumor sizes ranged from 5 to 20 cm (median, 8 cm). All cases consisted of clear to faintly eosinophilic spindled cells arranged in fascicular and nested patterns. The cells had small but distinct nucleoli and low mitotic activity. Immunohistochemically, all cases were positive with antibodies to gp100 protein (HMB-45) and negative for S-100 protein. In three of the seven cases studied immunohistochemically, the tumors expressed smooth muscle actin, melan-A, microphthalmia transcription factor (MiTF), and myosin, but not desmin. No expression of the TSC2 gene product, tuberin, was seen in three cases. One case studied cytogenetically disclosed a t(3;10). Follow-up data, available in six of seven cases (median duration, 18 mos), showed five patients to be free of disease and one to have a radiographically presumed lung metastasis. We think these tumors comprise a new entity for which we propose the term "clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres." The differential diagnosis of these tumors includes clear cell sarcoma of tendons and aponeuroses, leiomyosarcoma, and angiomyolipoma.

Contemporaneous bilateral forearm triceps metastases from adenocarcinoma of the lung.

Haematogenous skeletal muscle metastases from non-small-cell lung cancer (NSCLC) are rare, and are even more uncommonly observed bilaterally. Usually, NSCLC metastasizes to the liver, adrenal glands, lung, bone, central nervous system and kidney. We report a case of a long-surviving patient with contemporaneous histologically proven bilateral muscle metastases in the right and left forearm triceps, from adenocarcinoma of the lung.

Giant cell tumor of tendon sheath: a light and electron microscopic study.

A neoformation has been surgically withdrawn from third finger extensor tendon of the right hand of a 52 year male subject. Light (LM) and electron microscope (EM) observations from a number of tissue fragments allowed the identification of tumor nature, which appeared a giant cell tendon sheath. Moreover, some structural patterns have been described and compared to the previously reported cases. In areas of major cell density, parenchyma does not show lobular or gland-like organization; on the other hand, wide zones characterized by an amorphous matrix, progressively replacing collagen and containing elongated cells, are present. Giant multinucleated cells, mostly localized close to collagen bundles, can also be revealed. Unexpectedly, no foam cells appear and no phagocytized cell debris can be identified in giant multinucleated cells. Engulfed crystals are, differently, evidentiated by electron microscopy, both in mono- and multinucleated cell cytoplasm. Their electron density and their localization within cytoplasmic vacuoles suggest the presence of calcium. A correlation between giant cells and osteoclasts is then proposed. Multiple variously oriented centrioles support the possible mitotic genesis of multinucleated giant cells, which never show, on the other hand, fusion features. Siderosomes and residual bodies are also present. An unusual, diffuse thickening of nuclear lamina, only interrupted at nuclear pore level, is described and discussed.

A new human pleomorphic rhabdomyosarcoma cell-line, HS-RMS-1, exhibiting MyoD1 and myogenin.

A number of human cell lines derived from alveolar or embryonal rhabdomyosarcoma (RMS) have been described. To our knowledge, however, no cell line established from pleomorphic RMS has been reported. We describe here the establishment and characterization of a new human cell line, HS-RMS-1, which originated from a typical pleomorphic RMS arising in the gluteal muscle of a 26-year-old man. HS-RMS-1 cells had pseudotetraploid complex karyotypes with no specific abnormalities. Both in vitro and in vivo the cells on light microscopic examination exhibited pleomorphic features with immunopositive reaction for myogenic antigens including MyoD1 and myogenin, although no Z band-like structures were detected electron-microscopically. RT-PCR demonstrated the expression of MyoD1 and myogenin in HS-RMS-1 cells at the mRNA level, and direct sequencing analysis revealed cDNAs of MyoD1 and myogenin identical to those previously reported. This cell line, HS-RMS-1, established from pleomophic RMS will be useful for further studies including the molecular aspects of human RMS.

Extraskeletal myxoid chondrosarcoma: multimodal diagnosis and identification of a new cytogenetic subgroup characterized by t(9;17)(q22;q11).

Extraskeletal myxoid chondrosarcoma is a rare malignant soft tissue tumour that can be difficult to diagnose correctly, especially preoperatively. We describe four cases of extraskeletal myxoid chondrosarcoma of the extremities diagnosed by a multimodal approach. The cytological examination of fine-needle aspirates showed small and round, mildly pleomorphic cells lying in sheets and cords, but also dispersed within a myxoid and metachromatic intercellular substance. Histological, electron microscopic and immunocytochemical examination also yielded findings compatible with the diagnosis of extraskeletal myxoid chondrosarcoma. Cytogenetic analysis demonstrated a t(9;22)(q22;q12) in two tumours and a t(9;17)(q22;q11) in the third and fourth. The translocation t(9;22)(q22;q12) has been described repeatedly in extraskeletal myxoid chondrosarcoma but never in other tumours; hence, the detection of this pathognomonic chromosome abnormality in short-term cultured cells from fine-needle aspirates verified the diagnosis in two of the cases. The t(9;17)(q22;q11) found in the last two cases probably represents a new cytogenetic subgroup of extraskeletal myxoid chondrosarcoma as it, too, is unknown in other contexts. The multimodal approach taken in these four cases enabled a definite diagnosis of a rare malignant tumour whose cytological and histological features alone are usually not sufficiently distinct to rule out other differential diagnostic possibilities.

[Transmission and scanning microscopy of elastofibroma ultrastructure]. / Studio ultrastrutturale a trasmissione e a scansione dell'elastofibroma.

Elastofibroma is a rare benign tumor of soft tissues that has the elective localization in peri- or interscapular region. It is characterized by the proliferation of fibroblast-like cells which appear enveloped by abundant elastic and collagen fibers. Here we present a case of elastofibroma, observed in a 63 year old woman in the interscapular region. The neoformation has been studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Our hypothesis is the possibility that elastofibroma is the consequence of active neoformation of fibers elastic normal in the quality that subsequently is meet to progressive degenerative phenomenons.

Ultrastructural studies of tubules, analogous to skeletal cell T-tubules, in alveolar soft part sarcoma.

Tumor tissues from six patients with alveolar soft part sarcoma (ASPS) were investigated ultrastructurally to determine the presence of smooth tubules associated with plasmalemmal invaginations. Two different types of smooth tubular structures were identified: an aggregated and a dispersed type. The aggregated type (found in one of the six ASPSs) showed marked aggregation of many elongated smooth tubules without ribosomes associated with the plasmalemma. In the dispersed type (observed in the remaining five ASPSs), there was a conspicious appearance of a few smooth tubules scattered throughout the cytoplasm. Smooth tubules were the main component in both types, suggesting that both types appeared to have the same origin, although there were some differences in number, appearance, and distribution of the tubules between the two types. The smooth tubules in both types were classified into three different subtypes on the basis of materials in the tubular lumen. Ultrastructual observation and a plasmalemmal tracer-method, showed smooth tubules in continuity with the plasmalemma in three of the six cases, indicating that the tubules originated from the plasmalemma. Since the tubular structures were found in the tumor tissues of all six patients, they are probably one of the characteristic features of ASPS.

Rhabdomyosarcoma. Morphologic, immunohistochemical, and DNA study.

In this study 80 cases of predominantly adult rhabdomyosarcoma are presented as follows: 20 cases of the embryonal type, 32 cases of the alveolar and 8 cases of the pleomorphic type. Additional histologic classification was performed in each type. In myotube stage the histologic picture of fetal muscles cannot be compared to the alveolar type of rhabdomyosarcoma. Desmin and sarcomeric actin are observed in 47.7% of all cases, and myoglobin and myosin in only 23.1%. The reactions were diffuse, disperse, or focal. Electron microscopic study subdivides desmin positive tumors into three groups of differentiation. DNA analysis shows that most desmin positive cells are diploid in comparison to all the tumor cells that are hyperdiploid and tetraploid.

Postradiation malignant triton tumor. A case report and review of the literature.

OBJECTIVE: To report the third case of postradiation malignant triton tumor and to review the literature on malignant triton tumor with regard to features of possible prognostic significance. DATA SOURCES: Published articles were retrieved through MEDLINE, and additional articles were obtained through searches of the bibliographies. STUDY SELECTION: Cases were selected on the basis of histologic, immunohistochemical, and ultrastructural studies of malignancies showing both neurogenic and myogenic differentiation. Only those cases with survival data were selected for analysis. DATA EXTRACTION: The relationship between survival time and the possible prognostic variables of sex, presence or absence of von Recklinghausen's disease, age, and tumor location were evaluated by Cox regression analysis. RESULTS: Kaplan-Meier analysis showed a 5-year specific survival of 26%. Tumor location showed a statistically significant association with survival time (P = .01). CONCLUSIONS: This study suggests that malignant triton tumors occurring in the upper extremities, lower extremities, and head and neck have a better prognosis than tumors located in the retroperitoneum, buttock, or trunk. It is not clear if this variation is due to a difference in tumor grade, tumor stage, or resectability, or if it is a consequence of therapy.

Venous hemangioma of the temporalis muscle.

A 14-year-old girl presented with a diffuse venous hemangioma of the right temporalis muscle. The muscle had become swollen, thinning the underlying zygomatic and temporal bones. Magnetic resonance (MR) imaging demonstrated a diffuse isointense area containing high intensity foci on the T1-weighted images, and a serpiginous high intensity pattern on the T2-weighted images. A biopsy specimen revealed irregularly dilated veins in the fibrous stroma of the muscle. Diffuse abnormal signals on MR images may be a pathognomonic feature of intramuscular venous hemangiomas.

Solid alveolar rhabdomyosarcoma of the hand in adolescence: a clinical, histologic, immunologic, and ultrastructural study.

Rhabdomyosarcoma (RMS), a high-grade, malignant, skeletal muscle tumor, represents approximately 5% of neoplasms in children. The poorly differentiated forms of RMS are often not easily diagnosed and classified. Among the four histologic variants, alveolar RMS is the least frequently reported subtype. A poorly differentiated solid variant of alveolar RMS occurred on the right hand of a 16-year-old girl. Because of the tumor size, local invasiveness, and occurrence of cutaneous and breast metastases at presentation, the clinical staging was group IV (T2/NO/M1). Surgical excisions of the primary and metastatic locations were performed and chemotherapy with vincristine, dactinomycin, cyclophosphamide, and doxorubicin was administered. Light and electron microscopy studies revealed a solid proliferation with a focal alveolar pattern of monomorphous, small, round neoplastic cells without easily detectable muscular morphologic features. The skeletal muscle origin was revealed by the positive immunostaining for desmin, alpha-sarcomeric actin, muscle-specific actins, and enolase, and confirmed by immunoblotting for desmin. Despite the age of our patient, which is considered by some authors an independent predictor of outcome, all prognostic variables were unfavorable. However, a disease-free interval during three years of follow-up underlines the importance of multidisciplinary regimens for the treatment of this rare solid tumor of childhood and adolescence.

Chordoid tumor: a light, electron microscopic, and immunohistochemical study.

Chordoid tumor--synonymous with chordoid sarcoma, parachordoma, and peripheral chordoma--is a very rare neoplasm with histologic similarity to chordoma that is found outside the axial skeleton. A soft tissue chordoid tumor in the gluteus maximus muscle of a 42-year-old man is presented. This tumor had morphologic features identical to a chordoma: nodular growth with vacuolated cytoplasm and myxomatous stroma by light microscopy, positive immunoreaction for cytokeratin and epithelial membrane antigen by immunohistochemistry, desmosomes, intercellular lumina lined with microvilli, and the presence of basal lamina material by electron microscopy. Two similar cases have been reported in the English literature.

[Alveolar sarcomas of soft tissues. Immunohistochemical, ultrastructural study and flow cytometry]. / Les sarcomes alveolaires des parties molles etude immunohistochimique, ultrastructurale et cytometrie en flux.

Alveolar soft tissue sarcoma is an unusual tumor, known to have a poor prognosis. Although a muscular origin has been supported by most authors, the histogenesis of such tumors remains unclear. We report a case of alveolar soft tissue sarcoma with histological, ultrastructural, immunohistochemical and flow cytometry study. Pour results support a myogenic origin of these tumors and demonstrate its aneuploid nature. Pulmonary metastasis occurred early in spite of intensive chemotherapy and surgical removal of the tumor.