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. This is opposed to secondary types of cutaneous ossification that can occur in 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 (as in endochondral ossification of the skeletal system).

The lesions of osteoma cutis differ from calcinosis cutis in that they represent bone formation (dermal deposition of hydroxyapatite crystals) versus calcium salt deposits.

The pathogenesis of primary osteoma cutis has the following two proposed mechanisms[3] :

Epidemiology

Frequency

United States

Although considered rare, with no well-defined data on incidence, a plethora of conditions and syndromes may be found in association with osteoma cutis. Hence, the frequency of its occurrence varies accordingly. Primary lesions with no underlying cause are even rarer, but they account for approximately 20% of all skin ossifications. Reported in 1977, of 20,000 consecutive skin biopsies, only 35 cutaneous osteomas were found. Ten of them were primary, while 25 appeared secondary to another abnormality (although long ago, this allows some insight into its rarity).[1, 2]

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. Of note, multiple miliary osteoma cutis classically presents in middle-aged white women.[4]

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. There are four clinical types: isolated, widespread, multiple miliary facial, and platelike osteomas. Hence, they may present as single or multiple hard nodules, miliary tumors, or plaques.[5, 6] The face, scalp, extremities, digits, and subungual areas are most commonly affected.

See the images below.


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Solitary nodule on the frontal part of the scalp.


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

Causes

Osteoma cutis can be a feature of several groups of patients. In can be secondary to inflammatory skin diseases, trauma/scars, and cutaneous tumors. It can also occur with genetic syndromes or in isolation.

Albright hereditary osteodystrophy is due to an autosomal dominant defect in the alpha subunit of intracellular G proteins.[7] The characteristic phenotype includes short stature, round facies, defective teeth, mental retardation, brachydactyly (fourth and fifth metacarpals/"knuckle knuckle dimple dimple" of the Archibald sign), and osteomas of the soft tissue and the skin. Classically, it presents with pseudohypoparathyroidism (elevated parathyroid hormone [PTH], hypocalcemia, hyperphosphatemia secondary to renal PTH resistance). Tetany is often the presenting sign, secondary to the low calcium level. Albright hereditary osteodystrophy can cause osteoma cutis without endocrine abnormalities in the pseudo-pseudohypoparathyroidism variant.

Progressive osseous heteroplasia is also, like Albright hereditary osteodystrophy, associated with a defect in the alpha subunit of G proteins (GNAS1 gene). It is characterized by ossification of the dermis in infancy, with progression to the subcutaneous and deeper connective tissues throughout childhood. It is not associated with endocrine changes, but it can have a severe affect on growth and joint mobility.[6]

Congenital platelike osteomatosis, a type of primary osteoma cutis, meets the following criteria:

Congenital platelike osteomatosis is most commonly found on the scalp. It should be monitored, as its diagnosis could be representative of a slow-evolving progressive osseous heteroplasia (something with much more severe consequences).[8]

Fibrodysplasia ossificans heteroplasia and fibrodysplasia ossificans progressiva (stone man syndrome) are possible causes.

Osteoma cutis can be found in patients with Gardner syndrome, which includes colonic polyposis, retinal hyperplasia, and other osseous and soft tissue growths.

Multiple miliary osteomas of the face often present in patients with a history of severe acne, sunburn, neurotic excoriation, or dermabrasion. These small, hard papules can have a bluish hue, especially in patients who have been exposed to tetracycline treatment.[9, 4]

Laboratory Studies

Serum calcium, phosphorous, 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 can be performed for diagnosis, relief of discomfort, and cosmesis.

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.

See the images below.


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


View Image

Osteoma cutis is often identified as an incidental finding on examination of re-excision specimens. This excisional specimen failed to reveal residual....


View Image

High-power examination reveals adipocytes centrally and a prominent calcified matrix surrounded by osteoid.

Medical Care

Removal by excision or laser resurfacing to unroof overlying skin may be performed.[10] Treatment with the Er:YAG laser may result in less hypopigmentation and scarring than with the carbon dioxide laser.[11]

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

Luke Lennox, MD, Resident Physician, Department of Medicine, University of Buffalo, State University of New York School of Medicine and Biomedical Sciences

Disclosure: Nothing to disclose.

Coauthor(s)

Thomas N Helm, MD, Clinical Professor of Dermatology and Pathology, University of Buffalo, State University of New York School of Medicine and Biomedical Sciences; Director, Buffalo Medical Group Dermatopathology Laboratory

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

William D James, MD, Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine

Disclosure: Nothing to disclose.

Additional Contributors

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

Kevaghn P Fair, DO is a member of the following medical societies: American Society for Clinical Pathology, American Society of Dermatopathology, and College of American Pathologists

Disclosure: Nothing to disclose.

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. Talsania N, Jolliffe V, O'Toole EA, Cerio R. Platelike osteoma cutis. J Am Acad Dermatol. Mar 2011;64(3):613-5. [View Abstract]
  4. 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]
  5. 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]
  6. 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]
  7. 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]
  8. Worret WI, Burgdorf W. [Congenital, plaque-like osteoma of the skin in an infant]. Hautarzt. Nov 1978;29(11):590-6. [View Abstract]
  9. 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]
  10. 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]
  11. 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]
  12. 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]
  13. 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]
  14. Ragsdale BD. Lever's Histopathology of the Skin. Philadelphia, Pa: Lippincott-Raven; 1997:965-7.
  15. Watsky KL. Arndt KA, ed. Cutaneous Medicine and Surgery. Philadelphia, Pa: WB Saunders; 1996:1828-31.
  16. Weedon D, ed. Skin Pathology. 2nd ed. New York, NY: Churchill Livingstone; 2002:355-7.

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.

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.

Osteoma cutis is often identified as an incidental finding on examination of re-excision specimens. This excisional specimen failed to reveal residual basal cell carcinoma, but an osteoma cutis was evident. Further examination reveals prominent calcification with only a very narrow rim of osteoid in the periphery.

High-power examination reveals adipocytes centrally and a prominent calcified matrix surrounded by osteoid.

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.

Osteoma cutis is often identified as an incidental finding on examination of re-excision specimens. This excisional specimen failed to reveal residual basal cell carcinoma, but an osteoma cutis was evident. Further examination reveals prominent calcification with only a very narrow rim of osteoid in the periphery.

High-power examination reveals adipocytes centrally and a prominent calcified matrix surrounded by osteoid.