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Pilomatricoma

Pilomatricoma is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • Benign, adnexal skin tumor derived from hair matrix cells
  • Slow-growing, hard, typically solitary nodule found in the dermis/subcutaneous layer of the skin
  • Most commonly occurs on the head and neck of children and young adults (1)
  • Variants:
    • Pilomatrix carcinoma, a rare malignant variant, can be locally invasive and have a high recurrence rate. Infrequent cases of metastases have been reported.
    • Perforating pilomatricoma
  • Synonym(s): pilomatrixoma; calcifying epithelioma of Malherbe; trichomatricoma
  • System(s) affected: integumentary

Epidemiology

Incidence
  • Pilomatricoma was first described in 1880 by Malherbe and Chenantais (2).
  • Incidence of pilomatricomas has not been well studied.
  • One study reported an incidence of 1.04% of all benign skin tumors examined and 0.08% of all histologic samples reviewed.
  • Slight female preponderance (male-to-female ratio, 1:1.1)
  • Most frequently occurs in patients <20 years old (37–46%), with some reports of a second smaller peak in the 5th to 7th decades of life

Etiology and Pathophysiology

  • Pilomatricomas derive from the primitive basaloid cells of the epidermis that differentiate into hair matrix cells with uncontrolled proliferation in the dermis/subcutaneous tissue
  • There are anecdotal reports of lesions arising in areas of trauma, insect bites, and surgery (3.9% of cases).

Genetics
  • Activating β-catenin gene (CTNNB1) mutations are thought to play an important role.
  • A high level of β-catenin results in the stimulation of cellular proliferation and/or inhibition of cell death.

Risk Factors

No known risk factors

Commonly Associated Conditions

Although uncommon, multiple pilomatricomas have been associated with the following conditions:

  • Myotonic dystrophy
  • Turner syndrome
  • Rubinstein-Taybi syndrome
  • Trisomy 19
  • Sotos syndrome
  • Gardner syndrome

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Citation

Stephens, Mark B., et al., editors. "Pilomatricoma." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117568/all/Pilomatricoma.
Pilomatricoma. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117568/all/Pilomatricoma. Accessed August 19, 2019.
Pilomatricoma. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117568/all/Pilomatricoma
Pilomatricoma [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 August 19]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117568/all/Pilomatricoma.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Pilomatricoma ID - 117568 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117568/all/Pilomatricoma PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -