Pathology Images

Growth and Bone Destruction Patterns

	Benign and non-growing (or extremely slowly growing) lesions are well circumscribed and show geographic pattern of bone destruction with a sclerotic rim. Geographic pattern refers to a well-defined area of lysis. The sclerotic rim is more commonly seen in the weight-bearing bones and represents bone reaction to the lesion. Its presence means that the bone has been given sufficient time to react. Some authors say that the sclerotic rim signifies benignancy to about 95%.
	If the lesion is growing more rapidly, it may still show a well-demarcated zone of bone destruction (geographic pattern), but it will lack a sclerotic rim. With continued growth, such lesions may show cortical expansion. Expansile growth pattern is defined as visible widening of the affected portion of bone. In many cases, an interrupted periosteal rim will surround the expanded portion of bone. This pattern may be seen in locally aggressive tumors and in low-grade malignancies.
	Rapidly growing lesions are poorly defined and may show aggressive, infiltrative patterns of bone destruction (permeative or "moth-eaten"). "Moth-eaten" pattern is defined as an ill-defined zone of multiple small radiolucencies that may coalesce.
	Permeative pattern is characterized by numerous tiny radiolucencies in between the residual bone trabeculae. Due to the minute size of radiolucencies the lesion may be difficult to see and to delineate on the plain film. Generally, the more rapidly growing a lesion, the more difficult it is to see on plain film. "Moth-eaten" and permeative patterns are indicative of destruction involving both medullary and cortical bone. They are seen in high-grade malignant neoplasms and in osteomyelitis.

Examples of Periosteal Reactions

	Slow-growing tumors provoke focal cortical thickening (solid periosteal reaction, or "buttress")
	Rapidly growing lesions penetrate through the cortex causing separation of the periosteum and formation of lamellated new bone. If the periosteum elevates to a significant degree, it can break forming an acute angle (Codman's triangle). This is seen in malignant bone tumors and in some other rapidly growing lesions such as aneurysmal bone cyst, or in reactive processes (osteomyelitis, and subperiosteal hematoma). Codman's triangle is usually free of tumor unless infiltrated through its open end or by transcortical growth.
	Other types of periosteal reaction in response to a rapidly growing lesion include "onion-skinning" and spiculated "hair-on-end" types.

Matrix Mineralization Patterns in Bone Tumors

Osteoid. Malignant osteoid can be recognized radiologically as cloud-like or ill-defined amorphous densities with haphazard mineralization. This pattern is seen in osteosarcoma. Mature osteoid, or organized bone, shows more orderly, trabecular pattern of ossification. This is characteristic of the benign bone-forming lesions such as osteoblastoma.

Chondroid. Radiologically, it is usually easier to recognize cartilage as opposed to osteoid by the presence of focal stippled or flocculent densities, or in lobulated areas as rings or arcs of calcifications. They are best demonstrated by CT. Whatever the pattern, it only suggests the histologic nature of the tissue (cartilage) but does not reliably differentiate between benign and malignant processes.

Information and Tables courtesy of UMDNJ website.

Osteosarcoma of the femur arising in the metaphyseal region. Note the Epiphyseal plate still as this type of tumor afflicts younger individuals

Ewing’s Sarcoma of the tibia as the irregular tan/red/brown tumor breaks through the cortex. Ewing’s mainly occurs in the diaphysis of long bones as seen here.

Photos courtesy of the Bone and Joint Pathology Index at Florida State University