Cytology of pilomatrixoma (calcifying epithelioma of Malherbe) in fine needle aspirates.

OBJECTIVE: To characterize the cytomorphologic features of pilomatrixoma.

STUDY DESIGN: Aspirate findings in nine cases of PMX were correlated with clinical data and subsequent histology. This relatively large volume of case material afforded an opportunity to test the cytologic criteria that have been proposed as diagnostic of pilomatrixoma in the case reports published previously.

RESULTS: Ghost cells, basaloid cells and calcium deposits were the features found to be most characteristic of PMX and were observed in all four cases in which a correct diagnosis was made originally.

CONCLUSION: The presence of ghost cells seems to be the key to recognizing PMX. These cells are visible in the majority of air-dried smears but seldom in alcohol-fixed smears. Adequate cytologic sampling and the routine use of both wet-fixed and air-dried smears should preclude an incorrect diagnosis.