Pilomatricoma is a benign skin tumor derived from the hair matrix.

[2][3] These neoplasms are relatively uncommon and typically occur on the scalp, face, and upper extremities.

[7][8][9][10] This association has prognostic import, since cutaneous findings in children with Gardner syndrome generally precede colonic polyposis.

[citation needed] The characteristic components of a pilomatricoma include a stroma of fibrovascular connective tissue surrounding irregularly shaped, lobulated islands containing basaloid cells (being darkly stained, round or elongated, with indistinct cell borders and minimal cytoplasm, with nuclei being round to ovoid, deeply basophilic and generally prominent nucleoli), which abruptly or gradually transitions into ghost cells (having abundant, pale, eosinophilic cytoplasm, well defined cell borders and a central clear area, but only faint traces of nuclear material), which in turn may transition into keratinaceous to amorphous necrosis.

[11] The presence of calcifications with foreign-body giant cells is common within the tumors.