Malignant pilomatricoma in the parietal area

A 27-year-old Japanese woman presented with a 2.5-cm nodular subcutaneous lesion in the parietal area. The nodule was well demarcated and situated in the dermis and subcutis. Histologically, the tumor was diagnosed as malignant pilomatricoma. The tumor was excised, the postoperative course was uneventful, no evidence of local recurrence or distant metastasis was observed, and the patient continues to be under close follow-up. Malignant pilomatricoma, a locally aggressive counterpart of benign pilomatricoma, is also referred to as pilomatrix carcinoma. Most cases are excised as benign tumors; however, when the excision is incomplete local recurrence is likely, and distant metastases have also been reported. Histologically, the diagnosis can be challenging because no clear histologic criteria are available. Because of the rarity of malignant pilomatricoma, no welldefined standards in the surgical management of this neoplasm have been established. Moreover, since distant metastases have been described, close followup of the lesion is requisite.