Osteoma Cutis

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Background

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.[1, 2]

Pathophysiology

Bone arises in skin and soft tissues through mesenchymal (membranous) ossification without cartilage precursors or models (enchondral ossification, as in the skeletal system).

The lesions of osteoma cutis differ from tumoral calcinosis in that they represent bone formation, and calcinosis refers to calcium salt deposits.

In addition to colonic polyposis, epidermal cysts of the face and the scalp, and multiple fibromas, osteomatosis in the form of intraosseous (not cutaneous) osteomas may develop within the membranous bones of the head in Gardner syndrome.

Epidemiology

Frequency

United States

Although said to be rare, with no well-defined data on the incidence, a plethora of conditions and syndromes may be found in association with osteoma cutis, and the frequency of its occurrence varies accordingly. Primary lesions with no underlying cause are even rarer, but they account for approximately 20% of all cases.

Mortality/Morbidity

Osteoma cutis is not life threatening, although local discomfort and/or disfigurement may lead the patient to seek consultation.

Race

No particular race is predisposed to developing osteoma cutis.

Sex

Generally, no distinct sexual predominance exists. However, one cause of osteoma cutis, Albright hereditary osteodystrophy, occurs with a female-to-male ratio of 2:1.

Age

Osteoma cutis may occur at any age.

History

Patients may report having hard areas in the skin. A familial occurrence of Albright hereditary osteodystrophy may be present.

Physical

The presentations of osteoma cutis can be highly variable, with clinical entities that are defined by the number, the form, and the location of the lesions. Osteomas may present as single or multiple, extremely hard nodules, plaques, or miliary tumors.[3, 4] The face, the extremities, the scalp, the digits, and the subungual regions are the most commonly affected sites.

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).[5] 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.[6, 7]

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.

Laboratory Studies

Serum calcium and parathyroid hormone (PTH) levels help to define Albright hereditary osteodystrophy.

Imaging Studies

Plain radiographs demonstrate lesions but are not necessary for diagnosis.

Procedures

Excisional biopsy for diagnosis, relief of discomfort, or cosmesis may be performed.

Histologic Findings

Small spicules to large masses of mature bone are found in the dermis or extend into the subcutaneous tissue. Spicules of bone may enclose areas of mature fat, recapitulating a medullary cavity, but hematopoietic elements are seldom observed.


View Image

A microscopic view of osteoma cutis shows well-formed mature trabecular bone just beneath the epidermis. Note the absence of hematopoietic elements in....

Medical Care

Removal by excision or laser resurfacing to unroof overlying skin may be performed.[8] Treatment with the Er:YAG laser may result in less hypopigmentation and scarring than with the carbon dioxide laser.[9]

Other reported treatments with unproven efficacy include the following:

Consultations

When several lesions are noted, especially in pediatric patients, evaluation for associated syndromes may be warranted.

Prognosis

Osteosarcoma or other malignancies have not been reported to arise within osteoma cutis.

Author

Kevaghn P Fair, DO, Consultant Pathologist and Founder, Dominion Pathology Laboratories

Disclosure: Nothing to disclose.

Specialty Editors

James W Patterson, MD, Professor of Pathology and Dermatology, Director of Dermatopathology, University of Virginia Medical Center

Disclosure: Nothing to disclose.

David F Butler, MD, Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

Disclosure: Nothing to disclose.

Rosalie Elenitsas, MD, Herman Beerman Professor of Dermatology, University of Pennsylvania School of Medicine; Director, Penn Cutaneous Pathology Services, Department of Dermatology, University of Pennsylvania Health System

Disclosure: Lippincott Williams Wilkins Royalty Textbook editor

Catherine M Quirk, MD, Clinical Assistant Professor, Department of Dermatology, University of Pennsylvania

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Director, Ackerman Academy of Dermatopathology, New York

Disclosure: Nothing to disclose.

Additional Contributors

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous Chief Editor, William D. James, MD, to the development and writing of this article.

References

  1. Burgdorf W, Nasemann T. Cutaneous osteomas: a clinical and histopathologic review. Arch Dermatol Res. Dec 12 1977;260(2):121-35. [View Abstract]
  2. Roth SI, Stowell RE, Helwigeb. Cutaneous ossification. Report of 120 cases and review of the literature. Arch Pathol. Jul 1963;76:44-54. [View Abstract]
  3. Cohen PR, Tschen JA, Schulze KE, Martinelli PT, Nelson BR. Dermal plaques of the face and scalp. Platelike osteoma cutis. Arch Dermatol. Jan 2007;143(1):109-14. [View Abstract]
  4. Coutinho I, Teixeira V, Cardoso JC, Reis JP. Plate-like osteoma cutis: nothing but skin and bone?. BMJ Case Rep. May 5 2014;2014:[View Abstract]
  5. Ward S, Sugo E, Verge CF, Wargon O. Three cases of osteoma cutis occurring in infancy. A brief overview of osteoma cutis and its association with pseudo-pseudohypoparathyroidism. Australas J Dermatol. May 2011;52(2):127-31. [View Abstract]
  6. Riahi RR, Cohen PR. Multiple miliary osteoma cutis of the face after initiation of alendronate therapy for osteoporosis. Skinmed. Jul-Aug 2011;9(4):258-9. [View Abstract]
  7. Chabra IS, Obagi S. Evaluation and management of multiple miliary osteoma cutis: case series of 11 patients and literature review. Dermatol Surg. Jan 2014;40(1):66-8. [View Abstract]
  8. Altman JF, Nehal KS, Busam KJ, Halpern AC. Treatment of primary miliary osteoma cutis with incision, curettage, and primary closure. J Am Acad Dermatol. Jan 2001;44(1):96-9. [View Abstract]
  9. Kim SY, Park SB, Lee Y, Seo YJ, Lee JH, Im M. Multiple miliary osteoma cutis: treatment with CO(2) laser and hook. J Cosmet Laser Ther. Oct 2011;13(5):227-30. [View Abstract]
  10. Cohen AD, Chetov T, Cagnano E, Naimer S, Vardy DA. Treatment of multiple miliary osteoma cutis of the face with local application of tretinoin (all-trans-retinoic acid): a case report and review of the literature. J Dermatolog Treat. Sep 2001;12(3):171-3. [View Abstract]
  11. Baskan EB, Turan H, Tunali S, Toker SC, Adim SB, Bolca N. Miliary osteoma cutis of the face: treatment with the needle microincision-extirpation method. J Dermatolog Treat. 2007;18(4):252-4. [View Abstract]
  12. Ragsdale BD. Lever's Histopathology of the Skin. Philadelphia, Pa: Lippincott-Raven; 1997:965-7.
  13. Watsky KL. Arndt KA, ed. Cutaneous Medicine and Surgery. Philadelphia, Pa: WB Saunders; 1996:1828-31.
  14. Weedon D, ed. Skin Pathology. 2nd ed. New York, NY: Churchill Livingstone; 2002:355-7.

A microscopic view of osteoma cutis shows well-formed mature trabecular bone just beneath the epidermis. Note the absence of hematopoietic elements in the medullary spaces.

A microscopic view of osteoma cutis shows well-formed mature trabecular bone just beneath the epidermis. Note the absence of hematopoietic elements in the medullary spaces.

Solitary nodule on the frontal part of the scalp.

Miliary cutaneous osteomata. Multiple, small, bluish, stony-hard nodules in an acneiform distribution along the cheeks.