• 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



  • 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).


  • 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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