A 32-year-old female patient presents with concern about a growth that she recently noted on her left leg. She denies pain or discomfort and gives no personal or family history of similar lesions. Examination reveals a firm 1.5-cm nodule with slight blue coloration. Palpation does not elicit tenderness.
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Pilomatricoma, also referred to as calcifying epithelioma of Malherbe, is a benign neoplasm of the skin.1 As the name calcifying epithelioma denotes, calcium deposits are present in the majority of these lesions.2 Pilomatricoma formation tends to favor hair-bearing regions, such as the head, neck, and upper extremities. The lesion is an asymptomatic, firm, slowly enlarging nodule measuring between 0.5 cm and 3 cm in diameter. The lesion is typically skin colored, however, some may have blueish pigmentation. Although it can appear in all age groups, pilomatricoma is more common in children and adolescents.3 Pilomatricoma is a possible marker for certain medical conditions such as myotonic dystrophy, Rubinstein-Taybi syndrome, Turner syndrome, Goldenhar syndrome, and sarcoidosis.1 Rarely, lesions may undergo malignant transformation into a pilomatrix carcinoma.2
Histologic evaluation of pilomatricoma characteristically shows ghost cells, shadow cells, and/or basophilic cells.2 In some cases, imaging studies may be recommended to help exclude a diagnosis of malignancy or to determine lesion depth.4 First-line treatment is surgical resection.
1. Thompson L. World Health Organization classification of tumours: pathology and genetics of head and neck tumours. Ear Nose Throat J. 2006;85(2):74.
2. DeRosa DC, Lin-Hurtubise K. Pilomatricoma: an unusual dermatologic neoplasm. Hawaii J Med Public Health. 2012;71(10):282-286.
3. Erol B, Kucukkurt S, Bicer Aytugar T, Aksakalli N. Uncommon benign tumour of the skin: infraorbital pilomatricoma. BMJ Case Rep. 2016. doi:10.1136/bcr-2015-213561
4. Hwang JY, Lee SW, Lee SM. The common ultrasonographic features of pilomatricoma. J Ultrasound Med. 2005;24(10):1397-1402.