Osteoma Cutis


 

Strictly defined, osteoma cutis refers to the presence of bone within the skin in the absence of a preexisting or associated lesion, as opposed to secondary types of cutaneous ossification that occur by metaplastic reaction to inflammatory, traumatic, and neoplastic processes.

 

Causes:

 

Osteoma cutis is a feature in several groups of patients.

 

Albright hereditary osteodystrophy, which includes most patients with pseudohypoparathyroidism and pseudopseudohypoparathyroidism, is due to an autosomal dominant defect in the alpha subunit of intracellular guanyl nucleotide-binding protein (G protein).

 

  • The characteristic phenotype includes short stature, a round face, defective teeth, mental retardation, brachydactyly, and osteomas of the soft tissue and the skin.
  • Tetany is often the presenting sign of pseudohypoparathyroidism, formerly called Albright hereditary osteodystrophy. In addition to skeletal system abnormalities, lesions of osteoma cutis are frequently observed.

 

Single, small osteomas, arising later in life, sometimes with transepidermal elimination of bony fragments may be a cause.

 

Multiple miliary osteomas of the face following acne, neurotic excoriation, or dermabrasion are possible causes.

 

Congenital plaquelike osteomatosis or limited dermal ossification is generally present from birth; the skin of the scalp or the extremities is often affected.

 

Fibrodysplasia ossificans heteroplasia and fibrodysplasia ossificans progressiva are possible causes.

 

Miscellaneous rare disorders with or without cartilaginous elements include osteomas of the distal extremities and multiple osteomas of childhood unrelated to Albright hereditary osteodystrophy.