What is a pilomatrixoma?

Updated: Jan 30, 2020
  • Author: Ginard I Henry, MD; Chief Editor: Gregory Gary Caputy, MD, PhD, FICS  more...
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Pilomatrixoma, which is also known as pilomatricoma and the calcified epithelioma of Malherbe, is a variation of the epidermal cyst and should be included in the differential diagnosis. It is a relatively uncommon tumor and tends to occur on the neck, head, and upper extremities of children and young adults. Typically, it presents as a solitary, hard subcutaneous nodule, with attachment to the skin and occasional episodes of inflammation and pain.

The lesion is a nodular subepidermal tumor with elements of hair matrix. Intensely basophilic-staining cells are found peripherally, and eosin-favoring cells are near the center. Also present are shadow or ghost cells, which are cells with eosinophilic cytoplasm with what appear to be vacuolated areas where the nuclei formerly were present. Calcificiation is common.

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