What Are These Asymptomatic Lesions on the Face?

A 51-year-old white woman presented with multiple long-standing, asymptomatic, small, bluish subcutaneous papules on the bilateral cheeks and forehead. The patient reported that the bumps were painless and their appearance had become more visible over the past several months. She did not recount any precursor lesions in the involved areas. The patient reported that she had only had mild acne in the past and denied any other pertinent medical history or medications.

Physical exam revealed several firm, bluish-colored papules on the bilateral cheeks and the forehead (Figures 1 and 2). No evidence of acne or acne scarring was present. 

What is Your Diagnosis?

Diagnosis: Miliary Osteoma Cutis

Osteoma cutis is a rare, benign condition with less than 50 cases reported in the English literature. It is recognized as the presence of true bone within the dermis and subcutaneous tissue.¹There are two types of osteoma cutis: primary and secondary. Primary osteoma cutis is defined by new bone formation in the dermis without any evidence of a preexisting cutaneous condition.¹ Secondary osteoma cutis is more prevalent, occurring in 80% of cases, and is a sequela of past cutaneous lesions.^1,2 

Multiple miliary osteoma primarily affects the face and is rare, with only nine cases reported according to Goldminz and Greenberg.³ It most often presents as bluish papules and hardened nodules on the forehead and cheeks and predominantly affects middle-aged women with a history of acne (Figures 1 and 2).^2-5 

Etiology
Primary osteoma cutis is the rarer type and may be due to an underlying genetic syndrome such as Albright’s hereditary osteodystrophy, fibrodysplasia ossificans progressiva, progressive osseous heteroplasia, and plate-like osteoma cutis.^1,2,4,6 Secondary osteoma cutis can be the sequelae of various dermatologic lesions including acne vulgaris, nevi, scleroderma, pilomatrixoma, dermatomyositis, basal cell carcinoma, scars, inflammation, trauma, calcification, fibrous proliferations, among others.^1,6 Secondary osteoma cutis is subclassified into four categories based on location and progression: plate-like, isolated, widespread, and multiple miliary facial osteomas.⁴ Serum laboratory alterations are usually not seen in this group of conditions.^4,6 The patient in our case had a preexisting history of mild acne vulgaris. Therefore, our patient was characterized as having secondary miliary osteoma cutis. Her lesions were asymptomatic and appeared as bluish subcutaneous papules on her cheeks and forehead.  

Burgdorf and Nasemann⁷ reported two possible processes regarding the pathogenesis and etiology of osteomas. The first theory assumes a disordered embryologic process in which primitive mesenchymal cells differentiate normally into osteoblasts but migrate to the wrong location. The second theory interprets the presence of bone as a result of osteoblastic metaplasia of mesenchymal cells, such as fibroblasts.^1,6

Treatment  
Multiple modalities have been used to treat miliary osteoma cutis. Some suggest that topical tretinoin may be useful in the transepidermal elimination of the bone formation.^8,9 Others reported success with surgical treatments such as scalpel incision, curette extraction, needle microincision, and punch biopsy.³ Ratnavel et al⁵ used a standard scalpel excision to remove multiple miliary cutaneous osteomas in one patient with good cosmetic outcome. Fulton¹⁰ took a different approach, using dermabrasion and punch biopsies; this improved acne scarring and lessened the possibility of postinflammatory hyperpigmentation. Baskan et al¹¹ utilized the needle microincision extirpation method to remove bone fragments. Others effectively utilized the erbium: yttrium aluminium garnet and carbon dioxide lasers to remove both the epidermis and upper dermis area covering the cutaneous osteomas.⁶ 

Our Patient
Biopsy of a lesion on the left cheek was performed. Histopathological examination revealed a minute fragment of trabecular bone with a diagnosis of osteoma cutis (Figure 3). The patient’s serum laboratory evaluation showed normal levels of serum calcium, phosphorus, parathyroid hormone, and complete blood count. A diagnosis of miliary osteoma cutis was made.

The patient was successfully treated with both topical application of tretinoin and punch excision of the larger lesions. Surgical treatment using a 5-mm punch incision was performed to treat the larger lesions within the cheek area. Tretinoin 0.1% cream was provided for small lesions on the forehead. The patient was highly satisfied with her results.

Conclusion 
Miliary osteoma cutis is primary extraskeletal bone formation that primarily affects the face and clinically presents as papules and hardened nodules.² It predominantly affects middle-aged women with a history of acne.^2-5 Treatment remains challenging and controversial. Topical retinoids have been reported as occasionally effective.^8,9 Minimally invasive procedures, such as implemented in this case, may provide excellent aesthetic results in removing larger lesions. However, further studies are needed to evaluate efficacy and satisfaction of these treatment regimens. 

Dr Nichols is the founding director of NicholsMD in Greenwich, CT. At the time of article acceptance, Ms Barresi was a nurse practitioner at NicholsMD.

Disclosure: The authors report no relevant financial relationships.  

References

1. Altman JF, Nehal KS, Busam KJ, Halpern AC. Treatment of primary miliary osteoma cutis with incision, curettage, and primary closure. J Am Acad Dermatol. 2001;44(1):96-99. doi:10.1067/mjd.2001.108377

2. Chabra IS, Obagi S. Evaluation and management of multiple miliary osteoma cutis: case series of 11 patients and literature review. Dermatol Surg. 2014;40(1):66-68. doi:10.1111/dsu.12389

3. Goldminz D, Greenberg RD. Multiple miliary osteoma cutis. J Am Acad Dermatol. 1991;24(5 Pt 2):878-881. doi:10.1016/0190-9622(91)70138-R

4. Caravaglio JV, Gupta R, Weinstein D. Multiple miliary osteoma cutis of the face associated with Albright hereditary osteodystrophy in the setting of acne vulgaris: a case report. Dermatol Online J. 2017;23(3). https://escholarship.org/uc/item/7513d80h. 

5. Ratnavel RC, Burrows NP, Pye RJ. Osteoma cutis as a sequela of acne. J Royal Society Med. 1994;87(2):107-108.

6. Bouraoui S, Mlika M, Kort R, Cherif F, Lahmar A, Sabeh M. Miliary osteoma cutis of the face. J Dermatol Case Rep. 2011;5(4):77-81. doi:10.3315/jdcr.2011.1082

7. Burgdorf W, Nasemann T. Cutaneous osteomas: a clinical and histopathologic review. Arch Dermatol Res. 1977;260(2):121-135. doi:10.1007/bf00561117

8. Smith CG, Glaser DA. Treatment of multiple miliary osteoma cutis with tretinoin gel. J Am Acad Dermatol. 1999;41(3 Pt 1):500. doi:10.1016/s0190-9622(99)70134-9

9. Moritz DL, Elewski B. Pigmented postacne osteoma cutis in a patient treated with minocycline: report and review of the literature. J Am Acad Dermatol. 1991;24(5 Pt 2):851-853. doi:10.1016/0190-9622(91)70131-k

10. Fulton JE Jr. Dermabrasion-loo-punch-excision technique for the treatment of acne-induced osteoma cutis.  J Dermatol Surg Oncol. 1987;13(6):655-659. doi:10.1111/j.1524-4725.1987.tb00532.x

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 Dermatol Treat. 2007;18(4):252-254. doi:10.1080/09546630701287878