Pilomatricoma (calcifying epithelioma of Malherbe)

Synonyms
Pilomatrikom, Epithelioma calcificans Malherbe, verkalkendes Epitheliom, Pilomatricoma, pilomatrixoma, calcifying epithelioma of Malherbe
Specialty
Dermatology · Skin tumours
Images
Clinical 1 · Histology 2
In the app
1 flashcards
Last updated
10/2026 · Dr. Pascal Bafteh
Contents
  1. Images (3)
  2. Definition
  3. Occurrence & epidemiology
  4. Aetiopathogenesis
  5. Clinical features
  6. Histology
  7. Diagnosis
  8. Differential diagnoses
  9. Keep learning in the app
  10. References (selection)
  11. Cross-references

Images (3)

Pilomatricoma (calcifying epithelioma of Malherbe) – AI illustration (not a patient photo): hard stone-like subcutaneous nodule with bluish-reddish shimmering overlying skin preauricular in a child (10-year-old child, preauricular)AI illustration
hard stone-like subcutaneous nodule with bluish-reddish shimmering overlying skin preauricular in a child (10-year-old child, preauricular)AI-generated illustration for teaching purposes – not a real patient photo.
Pilomatricoma (calcifying epithelioma of Malherbe) – histology (H&E, overview): several tumour islands with eosinophilic shadow (ghost) cell areas rimmed by a basophilic border of basaloid matrical cells with fine calcification, set in …Histology
histology (H&E, overview): several tumour islands with eosinophilic shadow (ghost) cell areas rimmed by a basophilic border of basaloid matrical cells with fine calcification, set in …Nephron, „Pilomatrixoma - intermed mag", CC BY-SA 3.0, via Wikimedia Commons · CC BY-SA 3.0 · Source
Pilomatricoma (calcifying epithelioma of Malherbe) – histology (H&E), detail: basaloid cells, ghost cells with empty nuclear spaces and a zone of necrosisHistology
histology (H&E), detail: basaloid cells, ghost cells with empty nuclear spaces and a zone of necrosisMikael Häggström, M.D, „Histopathology of pilomatricoma, high magnification", CC0, via Wikimedia Commons · CC0 · Source
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Definition

Pilomatricoma is a benign tumour arising from hair matrix cells. A characteristic feature is calcification, which makes the nodule feel hard.

Occurrence & epidemiology

It is most often diagnosed in children but also occurs in adults. In a series of 179 pilomatricomas of the head and neck, the mean age was 29.8 years and 45.3% of patients were younger than 18 years. Multiple pilomatricomas have been reported in association with myotonic dystrophy.

Aetiopathogenesis

The cause is a localised mutation in a hair matrix cell; most cases carry mutations in the CTNNB1 gene (beta-catenin), and BCL-2 is overexpressed.

Clinical features

  • Solitary hard nodule, skin-coloured, whitish, reddish or purplish; usually 5–10 mm, stable for years or slowly growing to several centimetres.
  • Mainly on the head and neck (series: neck 30.2%, cheek 16.8%, scalp 16.2%, brow and periorbital area 14.0%), but possible at any site.
  • Usually asymptomatic, occasionally tender; calcification often gives an angulated shape ("tent sign").
  • Rarely giant forms; pilomatrix carcinoma is very rare.

Histology

Well-circumscribed nodulocystic tumour of the lower dermis, not uncommonly extending into the subcutis. Basaloid cells resembling the hair matrix mature into anucleate eosinophilic shadow cells; calcification is frequent in these areas, with multinucleated giant cells at sites of rupture. A pigmented variant occurs in up to 11%.

Diagnosis

  • Dermoscopy: central whitish or grey-blue structureless area, sometimes erythema and telangiectases.
  • Ultrasound: detection of calcification (in 88.2% in a paediatric series); also visible on X-ray.
  • Histological confirmation.

Differential diagnoses

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References (selection)

  1. DermNet: Pilomatricoma
  2. DermNet: Pilomatricoma pathology
  3. Pilomatricoma of the head and neck: a retrospective review of 179 cases
  4. Clinical and pathological features of 209 cases of pilomatricoma in children: a retrospective study

Cross-references

Mentioned in

More skin tumours

Note: This page is intended for medical education and does not replace diagnosis or treatment decisions in individual cases.