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Genetic and Rare Diseases Information Center (GARD)

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Other Names for this Disease
  • Calcifying epithelioma of Malherbe
  • Pilomatricoma
  • PTR
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What is a pilomatrixoma?

What causes pilomatrixomas?

What is a pilomatrixoma?

A pilomatrixoma is a benign (non-cancerous) skin tumor that typically occurs in the head and neck area.[1] The tumor usually does not cause any symptoms, but it can be associated with pain. A pilomatrixoma often occurs during childhood but has been reported in individuals of all ages. It may be caused by a change (mutation) in the CTNNB1 gene. Pilomatrixomas have been reported to occur in multiple members of a family, although the pattern of inheritance has not been confirmed. Familial cases have been observed but the mode of inheritance has not been confirmed. Treatment focuses on surgical removal of the tumor. Pilomatrixomas usually occur in the absence of another condition but have been associated with some conditions including Gardner syndromemyotonic dystrophy (especially when multiple pilomatrixomas are present), and sarcoidosis.  A few cases of malignant (cancerous) pilomatrixoma have been reported.[2]
Last updated: 12/1/2010

What causes pilomatrixomas?

The cause of all pilomatrixomas is not fully known, but investigators have shown that at least 75% of individuals with pilomatrixomas have mutations in the CTNNB1 gene.[3] This gene is responsible for a protein that is needed to regulate cell growth and attachment. When the gene is not working properly, it can result in abnormal cell growth.[4]  It is thought that the tumors typically arise from cells that interact with hair follicle cells.[5]
Last updated: 12/1/2010

  1. Victor A. McKusick. Pilomatrixoma. OMIM. April 14, 2005; Accessed 11/29/2010.
  2. Suzy Duflo, Richard Nicollas, Stéphane Roman, Guy Magalon, Jean Michel Triglia. Pilomatrixoma of the Head and Neck in Children: A Study of 38 Cases and a Review of the Literature. Archives of Otolaryngology- Head and Neck Surgery. November 1998; 124(11):1239-1242. Accessed 11/29/2010.
  3. Jaggi Rao, Andrew Lin. Pilomatrixoma. Emedicine. May 21, 2010; Accessed 12/1/2010.
  4. CTNNB1. Genetics Home Reference. November 28, 2010; Accessed 12/1/2010.
  5. Pirouzmanesh A, Reinisch JF, Gonzalez-Gomez I, Smith EM, Meara JG. Pilomatrixoma: a review of 346 cases. Plastic and Reconstructive Surgery. December 2003; 112(7):1784-1789. Accessed 12/1/2010.