proliferating trichilemmal cyst

Synopsis

 microscopy

• Proliferating trichilemmal cysts grow rapidly and may also arise de novo.
• Although biologically benign, they may be locally aggressive, becoming large and ulcerated.
• Rarely, malignant transformation leads to distant metastases.
• No absolute clinical criteria can distinguish malignant from benign proliferating pilar tumors.
• The entire lesion must undergo histological evaluation to assess for malignancy.
• Atypia and a high mitotic rate are suggestive of malignancy.

See also

 trichilemmal cyst