Vulvar Pilomatrix Carcinoma: Morphologic and Molecular Features

Area of Science:

• Oncology
• Dermatopathology
• Genetics

Background:

• Pilomatrix carcinoma (PC) is a rare, malignant skin adnexal tumor.
• It typically arises from hair matrix cells, often on the head and neck.
• While locally aggressive, metastasis occurs in only 10% of cases.

Observation:

• A rare case of pilomatrix carcinoma on the clitoris, a third reported instance on external genitalia, is presented.
• This tumor exhibited an unusual clinical course with multiple metastases.
• Next-generation sequencing was performed on the tumor tissue.

Findings:

• The tumor harbored a characteristic CTNNB1 mutation, common in pilomatrix tumors.
• Pathogenic mutations in PTEN, PIK3CA, and ARID1A were identified.
• These additional mutations may account for the observed aggressive clinical behavior and metastasis.

Implications:

• This case expands the understanding of pilomatrix carcinoma's molecular landscape.
• The identified mutations (PTEN, PIK3CA, ARID1A) offer potential targets for future therapies.
• It highlights the importance of considering rare genital tumors and their aggressive potential.