A sarcoma is a malignant tumor, a type of cancer that arises from transformed cells of mesenchymal origin. Connective tissue is a broad term that includes bone, cartilage, fat, vascular, or hematopoietic tissues, and sarcomas can arise in any of these types of tissues. As a result, there are many subtypes of sarcoma, which are classified based on the specific tissue and type of cell from which the tumor originates. Sarcomas are primary connective tissue tumors, meaning that they arise in connective tissues. This is in contrast to secondary connective tissue tumors, which occur when a cancer from elsewhere in the body spreads to the connective tissue. The word sarcoma is derived from the Greek σάρκωμα sarkōma 'fleshy excrescence or substance', itself from σάρξsarx meaning 'flesh'.
A bone tumor is an abnormal growth of tissue in bone, traditionally classified as noncancerous (benign) or cancerous (malignant). Cancerous bone tumors usually originate from a cancer in another part of the body such as from lung, breast, thyroid, kidney and prostate. There may be a lump, pain, or neurological signs from pressure. A bone tumor might present with a pathologic fracture. Other symptoms may include fatigue, fever, weight loss, anemia and nausea. Sometimes there are no symptoms and the tumour is found when investigating another problem.
An osteosarcoma (OS) or osteogenic sarcoma (OGS) is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchymal origin and that exhibits osteoblastic differentiation and produces malignant osteoid.
In histology, osteoid is the unmineralized, organic portion of the bone matrix that forms prior to the maturation of bone tissue. Osteoblasts begin the process of forming bone tissue by secreting the osteoid as several specific proteins. When the osteoid becomes mineralized, it and the adjacent bone cells have developed into new bone tissue.
Chondrosarcoma is a bone sarcoma, a primary cancer composed of cells derived from transformed cells that produce cartilage. A chondrosarcoma is a member of a category of tumors of bone and soft tissue known as sarcomas. About 30% of bone sarcomas are chondrosarcomas. It is resistant to chemotherapy and radiotherapy. Unlike other primary bone sarcomas that mainly affect children and adolescents, a chondrosarcoma can present at any age. It more often affects the axial skeleton than the appendicular skeleton.
Fibrosarcoma is a malignant mesenchymal tumour derived from fibrous connective tissue and characterized by the presence of immature proliferating fibroblasts or undifferentiated anaplastic spindle cells in a storiform pattern. Fibrosarcomas mainly arise in people between the ages of 25–79 It originates in fibrous tissues of the bone and invades long or flat bones such as the femur, tibia, and mandible. It also involves the periosteum and overlying muscle.
Chondroblasts, or perichondrial cells, is the name given to mesenchymal progenitor cells in situ which, from endochondral ossification, will form chondrocytes in the growing cartilage matrix. Another name for them is subchondral cortico-spongious progenitors. They have euchromatic nuclei and stain by basic dyes.
Ewing sarcoma is a type of cancer that forms in bone or soft tissue. Symptoms may include swelling and pain at the site of the tumor, fever, and a bone fracture. The most common areas where it begins are the legs, pelvis, and chest wall. In about 25% of cases, the cancer has already spread to other parts of the body at the time of diagnosis. Complications may include a pleural effusion or paraplegia.
Orthopedic pathology, also known as bone pathology is a subspecialty of surgical pathology which deals with the diagnosis and feature of many bone diseases, specifically studying the cause and effects of disorders of the musculoskeletal system. It uses gross and microscopic findings along with the findings of in vivo radiological studies, and occasionally, specimen radiographs to diagnose diseases of the bones.
The Codman triangle is the triangular area of new subperiosteal bone that is created when a lesion, often a tumour, raises the periosteum away from the bone. A Codman triangle is not actually a full triangle. Instead, it is often a pseudotriangle on radiographic findings, with ossification on the original bone and one additional side of the triangle, which forms a two sided triangle with one open side. This two sided appearance is generated due to a tumor that is growing at a rate which is faster than the periosteum can grow or expand, so instead of dimpling, the periosteum tears away and provides ossification on the second edge of the triangle. The advancing tumour displaces the periosteum away from the bone medulla. The displaced and now lateral periosteum attempts to regenerate underlying bone. This describes a periosteal reaction.
In histopathology, a small-blue-round-cell tumour, also known as a small-round-blue-cell tumor (SRBCT) or a small-round-cell tumour (SRCT), is any one of a group of malignant neoplasms that have a characteristic appearance under the microscope, i.e. consisting of small round cells that stain blue on routine H&E stained sections.
Extraskeletal myxoid chondrosarcoma (EMC) is a rare low-grade malignant mesenchymal neoplasm of the soft tissues, that differs from other sarcomas by unique histology and characteristic chromosomal translocations. There is an uncertain differentiation and neuroendocrine differentiation is even possible.
The following is a simplified (deprecated) version of the 2021 WHO classification of the tumours of the central nervous system. Currently, as of 2021, clinicians are using the WHO grade 5th edition, which incorporates recent advances in molecular pathology.
Primary bone is the first bone tissue that appears in embryonic development and in fracture repair. It is characterized by its random position of collagen fibers. In most places in adults this tissue is replaced by secondary bone tissue except, for example, near the sutures of calvara or tooth sockets. The secondary bones have lower amounts of osteocytes so primary bone is much more easily penetrated by x-ray.
Adenocarcinoma of the lung is the most common type of lung cancer, and like other forms of lung cancer, it is characterized by distinct cellular and molecular features. It is classified as one of several non-small cell lung cancers (NSCLC), to distinguish it from small cell lung cancer which has a different behavior and prognosis. Lung adenocarcinoma is further classified into several subtypes and variants. The signs and symptoms of this specific type of lung cancer are similar to other forms of lung cancer, and patients most commonly complain of persistent cough and shortness of breath.
Sarcomatoid carcinoma, sometimes referred to as pleomorphic carcinoma, is a relatively uncommon form of cancer whose malignant cells have histological, cytological, or molecular properties of both epithelial tumors ("carcinoma") and mesenchymal tumors ("sarcoma"). It is believed that sarcomatoid carcinomas develop from more common forms of epithelial tumors.
A rhabdomyoblast is a cell type which is found in some rhabdomyosarcomas. When found histologically, a rhabdomyoblast aids the diagnosis of embryonal, alveolar, spindle cell/sclerosing, and pleomorphic rhabdomyosarcomas; however, in a tumor, expression of the rhabdomyoblast phenotype is not the only factor in diagnosing a rhabdomyosarcoma. Mesenchymal malignancies can exhibit this phenotype as well. Immunohistochemistry techniques allow for the sensitive detection of desmin, vimentin, muscle specific actin, and MyoD1. Similarly the rhabdomyoblast phenotype can be detected morphologically. Rhabdomyoblasts are early stage mesenchymal cells, having the potential to differentiate into a wide range of skeletal cells. Each stage of differentiation exhibits unique and distinguishable histological characteristics. In its initial from, stellate cells with amphiphilic cytoplasm and ovular central nuclei are observed. Commonly referred to as rhabdoid features, the maturing rhabdomyoblast will likely exhibit low levels of eosinophilic cytoplasm in proximal distances to the nucleus. As maturation and differentiation progress, the cell's cytoplasmic levels of white blood cells increase; additionally, elongated shapes, commonly depicted as “tadpole”, “strap” and "spider cells", are observed. In the concluding phase of differentiation, the white blood cell rich cytoplasm appears bright and exhibits cross-striation. The highly regulated organization of actin and myosin microfilaments in contractile proteins results in this appearance.
Fibroblastic and myofibroblastic tumors (FMTs) develop from the mesenchymal stem cells which differentiate into fibroblasts and/or the myocytes/myoblasts that differentiate into muscle cells. FMTs are a heterogeneous group of soft tissue neoplasms. The World Health Organization (2020) defined tumors as being FMTs based on their morphology and, more importantly, newly discovered abnormalities in the expression levels of key gene products made by these tumors' neoplastic cells. Histopathologically, FMTs consist of neoplastic connective tissue cells which have differented into cells that have microscopic appearances resembling fibroblasts and/or myofibroblasts. The fibroblastic cells are characterized as spindle-shaped cells with inconspicuous nucleoli that express vimentin, an intracellular protein typically found in mesenchymal cells, and CD34, a cell surface membrane glycoprotein. Myofibroblastic cells are plumper with more abundant cytoplasm and more prominent nucleoli; they express smooth muscle marker proteins such as smooth muscle actins, desmin, and caldesmon. The World Health Organization further classified FMTs into four tumor forms based on their varying levels of aggressiveness: benign, intermediate, intermediate, and malignant.
Extraskeletal Ewing sarcoma (EES), is a cancer of soft tissue, a type of Ewing sarcoma that does not arise from bone.
