Osteochondroma is a type of cartilage tumor that occurs on the bone surface, beneath the periosteum, and at the attachments of tendons and ligaments. It can be seen in various age groups from children to adults, typically located in the diaphysis or metaphysis of long bones, with a predilection for the proximal humerus.

bubble_chart Pathological Changes

1. Gross examination: The tumor is composed of lobules encased in dense, hyaline cartilage.

2. Microscopic examination: Compared to central cartilaginous bone tumors, it exhibits higher cellularity with larger cells; nuclei occasionally show slight variation in size, are plump, display grade I pleomorphism, and some binucleated cells are present. These features are considered "normal" and carry different prognostic implications compared to the identical histological appearance seen in central cartilaginous tumors of long bones or axial skeleton.

bubble_chart Clinical Manifestations

A slowly progressing grade II swelling can sometimes be quite large, with rare instances of swelling, accompanied by pain or not.

bubble_chart Auxiliary Examination

A saucer-shaped depression is visible on the cortex, which is quite shallow and occasionally presents as a grade I multiring pattern marked by sclerotic lines. It generally does not extend into the medullary cavity. The lens-shaped or hemispherical soft bone tumor mass has radiolucency similar to soft tissue and may occasionally contain radiopaque granules and shadows, indicating calcification and/or ossification of the cartilage. Along the periphery of the soft bone tumor, the bone membrane lifted from the cortex may produce spicules that encircle the base of the tumor.

If the bone membrane is soft and the bone tumor is asymptomatic with non-persistent growth (usually ceasing after body growth ends), the patient can be followed up without surgical treatment. If surgery is required, the tumor should be completely excised with marginal or wide resection to ensure a cure. However, intralesional excision also has a high success rate.