Simultaneous occurrence of calcification and amyloid deposit in pilomatricoma.

Amyloid deposition was encountered in 10 of 16 samples of pilomatricoma, indicating that the deposition of amyloid is nearly as common as calcification in pilomatricoma. In addition, a simultaneous occurrence of calcification and amyloid deposit in pilomatricoma was recognized in 9 of 16 samples. The calcification and the deposition of amyloid developed topographically in the same area within the shadow cell masses. Such an area was revealed as moderately basophilic, amorphous, or hyalinized by H&E staining. Electron microscopy revealed spotty calcium deposits in amyloid. No light chains of human immunoglobulin were detected in the amyloid-deposited area. Amyloid in this tumour may facilitate calcification or serve as a matrix for subsequent calcification.