Structures such as the marrow cavity and cortical bone of the osteochondroma are contiguous to those of the originating bone. Sites of origin often involve metaphyses of long bones. While many osteochondromas occur spontaneously, there are cases in which several osteochondromas can occur in the same individual; these may be linked to a genetic condition known as hereditary multiple osteochondromas. Osteochondroma appears on X-ray as a projecting mass that often points away from joints. These tumors stop growing with the closure of the parental bones growth plates. Failure to stop growth can be indicative of transformation to malignant chondrosarcoma. Treatment is not indicated unless symptomatic. In that case, surgical excision is often curative. Enchondroma
Enchondromas are benign tumors of hyaline cartilage. Within a bone, enchondromas are often found in metaphyses. They can be found in many types of bone, including small bones, long bones, and the axial skeleton. X-ray of enchondromas shows well-defined borders and a stippled appearance. Presentation of multiple enchondromas is consistent with multiple enchondromatosis (Ollier Disease). Treatment of enchondromas involves surgical curettage and grafting. Benign soft tissue tumors
Lipomas
Lipomas are benign, subcutaneous tumors of fat cells (adipocytes). They are usually painless, slow-growing, and mobile masses that can occur anywhere in the body where there are fat cells, but are typically found on the trunk and upper extremities. Although lipomas can develop at any age, they more commonly appear between the ages of 40 and 60.
Important distinctions have also been made between hard systems – technical in nature and amenable to methods such as systems engineering, operations research, and quantitative systems analysis – and soft systems that involve people and organisations, commonly associated with concepts developed by Peter Checkland and Brian Wilson through Soft Systems Methodology (SSM) involving methods such as action research and emphasis of participatory designs. Where hard systems might be identified as more "scientific", the distinction between them is often elusive. Cultural system
A cultural system may be defined as the interaction of different elements of culture. While a cultural system is quite different from a social system, sometimes both together are referred to as a "sociocultural system". A major concern of the social sciences is the problem of order. Economic system
An economic system is a mechanism (social institution) which deals with the production, distribution and consumption of goods and services in a particular society. The economic system is composed of people, institutions and their relationships to resources, such as the convention of property. It addresses the problems of economics, like the allocation and scarcity of resources. The international sphere of interacting states is described and analysed in systems terms by several international relations scholars, most notably in the neorealist school. This systems mode of international analysis has however been challenged by other schools of international relations thought, most notably the constructivist school, which argues that an over-large focus on systems and structures can obscure the role of individual agency in social interactions.