Skin nonmelanocytic tumor
Adnexal tumors
Hair follicles
Pilomatrixoma


Topic Completed: 1 June 2012

Minor changes: 16 October 2020

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PubMed Search: Pilomatrixoma [title] "loattrfree full text"[sb]

Christopher S. Hale, M.D.
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Cite this page: Hale C. Pilomatrixoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticpilomatrixoma.html. Accessed October 24th, 2020.
Definition / general
  • Also called pilomatricoma, calcified epithelioma of Malherbe
  • Benign tumor arising from hair matrix
  • Usually children and young adults in head, neck or upper extremities
  • Proliferating portion of tumor composed of small round blue cells - a pitfall on fine needle aspiration

  • Aggressive pilomatrixoma:
    • Atypical histology, locally invasive with local recurrence
  • Malignant pilomatrixoma:
    • Cytologic atypia, infiltrative border, transition to squamous cells
    • Clear cells, necrosis, mitotic figures, variable sarcomatoid features
    • Recurs locally, may metastasize
Case reports
Clinical images

Contributed by Mark R. Wick, M.D.

Breast skin



Images hosted on other servers:

Preoperative appearance of face pilomatricoma

Calcified pilomatricoma

Gross description
  • Nodular, subepidermal
Gross images

Contributed by Mark R. Wick, M.D.

Breast skin

Microscopic (histologic) description
  • Solid nests of basaloid cells undergoing abrupt trichilemmal-type keratinization
  • Ghost cells, often foreign body reaction, calcification or ossification with extramedullary hematopoiesis
  • Occasional transepidermal perforation
Microscopic (histologic) images

Contributed by Andrey Bychkov, M.D., Ph.D.

Nodule in derma

Basaloid nests

Basal cells, giant cells and ghost cells

Ghost cells



Contributed by Mark R. Wick, M.D. and Amy Lynn, M.D.

Breast skin

Pilomatrixoma



Contributed by Asmaa Gaber Abdou, M.D. and Mona Kandil, M.D.


Various images



Case #424

Various images



Contributed by Ulrich Vogel, M.D.




Images hosted on other servers:

Earlobe mass

Evolution of basaloid cells into shadow cells

Cytology description
  • Ghost cells, groups of basaloid cells, squamous cells in combination with multinucleated giant cells and calcium deposits in a background of debris (J Cytol 2011;28:1)
Cytology images

Case #424



Images hosted on other servers:

H&E, cluster of shadow cells

MGG, cluster of basaloid cells

MGG, abundant cytoplasm

Differential diagnosis
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