Intranuclear Undulating Membranous Structures in Cells of a Human Parosteal Osteosarcoma

Large numbers of paracrystalline undulating membranous structures (UMS) were observed in the nuclei of dense cells in a human parosteal osteosarcoma. The electron-dense walls of the structures were 15-20 nm thick, and circular profiles had an outer diameter of 60-70 nm and an inner diameter of 25-30 nm. The UMS-containing cell nuclei displayed a number of other characteristic features, including vermicellar bodies, large numbers of interchromatin granules, and prominent perichromatin granules. The possible significance of these features is discussed.     

Extraskeletal osteosarcoma histologically mimicking parosteal osteosarcoma

An extraskeletal osteosarcoma histologically mimicking parosteal osteosarcoma arising in a 63-year-old female is described. The intramuscular lesion in the left lower thigh was a 7 x 4 cm, well-defined mass with marked central calcification and ossification. The tumor was composed predominately of a centrally located osteocartilaginous component and a peripheral, non-osseous fibrous component. The former was characterized by a complex interanastomosing pattern of woven-bone trabeculae with small osteocytes and a minor cartilaginous element. The intratrabecular stroma consisted of benign-appearing fibroblasts. The peripheral fibrous part was characterized by fascicular and interlacing proliferations of spindle cells with mild atypia, rare mitosis and low to moderate cellularity. There were a few scattered foci of proliferating pleomorphic cells, constituting 5% of the tumor, indicating high-grade transformation. There was no evidence of zoning phenomena, cortical erosion, periosteal reaction or intramedullary involvement. The patient is well without recurrence or metastasis at 12 months follow up. This soft tissue neoplasm, mimicking parosteal osteosarcoma, should be distinguished from other bone-forming tumors or tumor-like lesions with which they may be confused. Pathologists and physicians should know the existence of this type of extraskeletal osteosarcoma and treat it as a high-grade extraskeletal osteosarcoma.     

Unusual Extraskeletal Myxoid Chondrosarcoma

We describe an unusual soft tissue tumor occurring within the rectus femoris muscle of a 64-year-old woman. The site, size, macroscopic, and histological appearances were all consistent with an extraskeletal myxoid chondrosarcoma. However, the present case differs significantly from previous reports of this uncommon tumor in that electron microscopy did not show any evidence of chondro-blastic differentiation. Furthermore, the cells failed to stain for vimentin while labeling intensely for neuron-specific enolase, contained large numbers of cytolysosomes having a multivesicular appearance, and focally produced an external lamina. Based on the typical histological appearances we conclude that this is an unusual variant of extraskeletal myxoid chondrosarcoma in which there is evidence of nerve sheath differentiation.     

Well-differentiated extraskeletal osteosarcoma: report of 2 cases, 1 with dedifferentiation

Extraskeletal osteosarcoma (ESOS) is a rare soft tissue sarcoma, typically characterized by high-grade histological features and a grave prognosis. However, 4 cases of well-differentiated ESOS with a better prognosis have been documented in the literature within the last 40 years. We report 2 additional cases, 1 with multicentric presentation and dedifferentiation, and we emphasize the histological features that are useful in distinguishing this lesion from other soft tissue tumors. Well-differentiated ESOS seems to represent a rare but distinct low-grade variant of ESOS. The limited published experience suggests that although the biologic behavior of this tumor is better than that of classical ESOS, there are cases with progression to a higher grade, leading eventually to final demise.     

Extraskeletal myxoid chondrosarcoma: a histochemical and immunohistochemical study

In reviewing a large series of soft tissue sarcomas, nine cases of extraskeletal myxoid chondrosarcoma have been retrieved. These tumours, which principally presented in middle-aged adults, have been examined histochemically to determine the heteroglycan content of their myxoid matrix and immunohistochemically for the presence of S-100 protein. The principal mucopolysaccharides identified were chondroitin-4 and 6-sulphate and keratan sulphate; each of the tumours was S-100 positive. The relevance of these findings to the histogenesis and differential diagnosis of these uncommon neoplasms is discussed.     

Small-cell extraskeletal osteosarcoma: case report and literature review

Small-cell extraskeletal osteosarcoma is extremely rare and consists of sheets of small round cells with variable amounts of osteoid. This tumor is often difficult to diagnose when tissue samples do not include recognizable osteoid. Only four cases have been reported in English and none in Chinese. We report a typical case of small-cell extraskeletal osteosarcoma occurring in the left leg of a 40-year-old female. Laboratory results were within normal limits. Magnetic resonance imaging demonstrated a soft tissue mass measuring 36 mm × 18 mm in the medial lateral aspect of left limb. The initial histological findings led to a misdiagnosis because the first fine-needle biopsy was randomized and incomplete. However, an open surgical specimen showed recognizable osteoid, which enabled us to make a definitive diagnosis. We also present clinical, radiologic and pathologic features of this case.     

Ultrastructural Analysis of Asteroid Bodies: Evidence for Membrane Lipid Bilayer Nature of Components

Electron microscopic examination of multiple asteroid bodies (ABs) from pulmonary tissue revealed that the core and spokes of these structures are composed of phospholipid bilayers organized in lamellar and tubular forms. These morphologic patterns followed the ones described previously for the lipid-water bulk interface systems. On light microscopy the ABs appeared surrounded by a halo of vacuoles corresponding ultrastructurally to loosely arranged myelin membranes. Transitional forms, between the tightly arranged phospholipid membranes forming the spokes and the loose myelin membranes surrounding them, were seen. Myelin membranes were seen in the cytoplasm of multinucleated giant cells, independent of ABs, in close association with intracellular spaces (lumina) and lined by abundant microvilli identical to the surface microvilli. These spaces were present in central areas of the cell and probably represent surface membrane remnants of partially fused cells. No centrioles, true microtubules, or collagen were seen in the multiple ABs examined. Immunoperoxidase stains for vimentin and tubulin were also negative in ABs. No calcium or phosphorus was seen by X-ray microanalysis. Thus the morphologic evidence is supportive of the hypothesis that, during or after the process of fusion of activated macrophages, the resulting excess of membranes (surface and lysosomal) contributes to the formation of ABs. No evidence supporting the notion that ABs are formed by the aggregation of preexisting cytoskeletal components was found.     

Extraskeletal Ewing's Sarcoma

A well documented case of extraskeletal Ewing's sarcoma arising in a finger of a 16-year-old man was studied by light microscopy, immunohisto-chemistry and electron microscopy. The differential diagnoses of similar “round cell neoplasms” are discussed. Emphasis is placed on the distinction between extraskeletal Ewing's sarcoma and peripheral neuroepithelioma.     

Gastric Carcinomas With Unusual Cytoplasmic Ultrastructural Features

Alterations in tannic acid (TA) binding capacity of cell surface carbohydrates in normal, premalignant, and malignant squamous epithelium of the human uterine cervix have been studied using electron microscopic visualization in combination with microdensitometric evaluation.

While in normal epithelium there is distinct binding in four to five cell layers of the deep intermediate zone, cells of carcinoma in situ and invasive cancer lesions lack TA binding. In moderate dysplasia an intermediate reacting pattern is found.

Deep intermediate cells in areas bordering the carcinoma in situ lesions do not show any binding, although their ultrastructure cannot be distinguished from similar cells in normal tissue.

The TA deposition within the deep intermediate zone is probably related to the presence here of glycoprotein-containing membrane-coating granules.

The finding that TA binding discriminates between cells in normal squamous epithelium and morphologically normal cells in juxtaposition with lesional areas in premalignant and malignant epithelium opens the possibility for a more reliable cytologic diagnosis of cervical epithelial neoplasia.     

Primary osteosarcoma of the breast

Presented herein is a case of primary pure osteosarcoma of the breast. A 59-year-old woman noticed a left breast tumor. Mammography showed a cluster of crushed stone-like calcifications, which gave the tumor a raw cotton-like appearance. Malignancy was suspected on fine-needle aspiration cytology of the tumor. An excisional biopsy was performed. The tumor was 2.0 × 2.4 cm in size. Histopathologically the tumor was composed of diffuse atypical cells with mitosis and a lot of bone. Atypical cells were thought to be neoplastic osteoblasts. Multinucleated osteoclastic cells were interspersed with osteoblasts. Spindle cells were found at the verge of the tumor. A few entrapped tubular structures were seen. Immunohistochemistry indicated that neoplastic osteoblastic cells of the tumor were stained positively for vimentin, but negatively for epithelial markers; which suggested that the tumor cell elements originated from epithelial cells. This tumor was diagnosed as primary extraskeletal osteosarcoma. Partial resection was additionally performed around the excisional biopsy without dissection of the axillary lymph nodes. Bone radionuclide scan after operation showed no abnormal uptake. At 5 years after surgery no recurrence was seen.     

Low-grade extraskeletal osteosarcoma of the mediastinum: report of a case and review of literature

Extraskeletal osteosarcoma (ESOS) is a rare soft tissue sarcoma, typically characterized by a bone-producing neoplasm. Low-grade extraskeletal osteosarcoma (LGESOS) is an extremely rare soft tissue tumor, and patients with LGESOS tend to have a better prognosis. Here, we reported a case of LGESOS of the mediastinum with lung metastasis, and describe its clinical, pathological and radiological features, and compared them with those of the reported cases.     

骨外黏液样软骨肉瘤2例报道及文献复习

目的探讨骨外黏液样软骨肉瘤的临床病理学特征。方法对2例骨外黏液样软骨肉瘤进行光镜观察及免疫组化染色标记,并通过相关文献复习,对病理诊断及鉴别诊断等指标进行分析。结果1例发生于足底,1例发生于乳腺。光镜下肿瘤呈分叶状,边界清。细胞为圆形及短梭形,成束状排列于黏液样基质中,局部可见围血管形成玫瑰花结样结构。部分肿瘤细胞异型性明显。免疫表型:vimentin、NSE、Syn均呈阳性;例1EMA灶性阳性,例2阴性;S-100蛋白、CgA及CK均阴性。结论骨外黏液样软骨肉瘤为罕见的软组织恶性肿瘤,具特异性的组织病理学特点。主要发生于四肢,少数可发生于实质器官,至今未有乳腺原发病例报道。部分肿瘤细胞可发生间变导致诊断困难,须与脊索瘤、骨内软骨肉瘤、化生性癌及黏液性肿瘤等鉴别。     

Primary Osteosarcoma of the Ovary

A case of primary osteosarcoma arising in the left ovary of a 75 year-old female is described. The chief complaint was a sensation of lower abdominal mass. An abdominal plain film showed a large calcified mass in pelvic region, and a preoperative diagnosis of "ovarian fibroma" was made. The excised tumor was divided into 4 pieces, resembling an oyster shell. Microscopically, the tumor fragments were composed of compact bone or woven bone with surrounding atypical osteoblasts and osteoclasts. The tumor was partly composed of numerous spindle cells with malignant osteoid or atypical chondroid formation, and diagnosed as "osteosarcoma". The cystic part of the lesion was lined with a single layer of columnar cells, but the tumor contained no other germ elements or stem cells, or malignant epithelium. Therefore, it is doubtful that this tumor originated from teratoma or malignant mixed mesodermal tumor, and we conclude that this ovarian osteosarcoma arose through a neoplastic change in ovarian stromal cells. The patient died 4 months after surgery due to intra-abdominal and intrathoracic dissemination of the tumor.     

Osteosarcoma with Prominent Epithelioid Features

Osteosarcoma in the metaphysis to epiphysis of the left femur of a 17 year old male is reported. The lesion appeared osteolytic with sclerotic foci on roentgenographs, accompanied by an extensive tumor shadow in the surrounding soft tissue. While 60% of the tumor was necrotic, histological examination of the remaining viable tissue revealed that it consisted almost entirely of a sheet of epithelioid cells, separated by thin, fibrovascular septa with an alveolar-like pattern, suggestive of metastatic carcinoma. Only a few areas were characterized by malignant osteoid tissue intermingled with the above cells, showing significant positivity for bone-specific alkaline phosphatase and 5 nucleotidase, thus permitting a diagnosis of osteosarcoma. Autopsy findings revealed that the metastatic foci were histologically similar to those of the primary tumor. Electron microscopy revealed poor development of cytoplasmic organelles, supporting possible derivation from an osteoblastic cell lineage at an early stage. Acta Pathol Jpn 39: 439 445, 1989.     

Primary osteosarcoma of the uterine corpus: case report and review of the literature

A rare case of rapidly growing osteosarcoma that developed in the uterine corpus of a 62-year-old woman is presented. The tumor occupied almost the entire pelvic cavity and extended into the abdominal cavity, with marked involvement of the intestines. Histopathologically, the tumor was composed of an osteoblastic component, accompanied by conspicuous bone formation, and a fibroblastic component. The tumor cells were positive for vimentin and osteocalcin, as well as desmin, alpha-smooth muscle actin and muscle-specific actin, but negative for h-caldesmon. The results indicated myofibroblastic differentiation in a part of the tumor. A review of 14 reported cases and our case of uterine osteosarcoma revealed that this tumor has a biologically aggressive nature, although its histopathological and immunohistochemical features are similar to those of osteosarcomas in soft tissue and bone. As the prognosis of patients with this tumor is poor, it is of importance to differentiate this tumor from other types of tumors arising from the uterine corpus.