Osteoma cutis defines a skin condition marked by bony growths under the skin without the presence of a lesion. Hard or firm bumps that appear white or bluish might appear on the face, scalp, arms, legs, or fingers, depending on the type of osteoma cutis. When the growths appear without a lesion, the condition is called primary osteoma cutis. Secondary osteoma cutis might form from an inflamed scar, severe acne, cancerous growth, or a hereditary thyroid disorder.
Primary osteoma cutis is considered rare, with no known cause. Bone fragments, also called cutaneous ossification, form under the surface of the skin and commonly contain fat and bone marrow cells. These small lumps pose no health risks, but may be unsightly and occur most often on the neck or head.
Secondary osteoma cutis is associated with an underlying condition that produces a lesion or tumor. One common link to the disorder is facial acne during adolescence that leaves scarring. Multiple miliary osteoma cutis refers to bony growths on the face and might not show up until middle age. The hard deposits typically appear upon both sides of the face. This form of the condition only affects women, but the reason is unknown.
Scientists found women who develop these bone growths have higher levels of collagen in the skin, but no direct connection between the disorder and collagen has been proven. Some skin specialists believe bone begins forming under the skin when something goes awry in the wound-healing process. They are not sure why calcium and phosphate develop under the skin in some people.
Osteoma cutis also appears in people diagnosed with Albright’s syndrome, a hereditary endocrine system disorder that often leads to hyperthyroidism later in life. The disease causes lesion formation on bones in early puberty. The affected skin commonly becomes pigmented, ranging from tan to dark brown.
Patients with Albright’s syndrome typically develop bumps on the scalp, arms, and legs. The growths might be present at birth and usually are not uniformly distributed. Children born with the disorder generally develop calcifications within the first two years of life. They typically do not grow to full height and may develop abnormal teeth and a round face.
Treatment of the disorder usually involves surgery to remove bone fragments from under the skin. Dermatologists might use a needle or scalpel to excise the growths before stitching the wound. Plastic surgery with laser treatment reduces the appearance of the lumps in some patients.