Proliferating trichilemmal cyst frequently manifests clinically as a subcutaneous nodule that gradually grows into a big nodular mass.

Rapid growth in some cases may be a sign of malignant development into cancer.

[3] Histologically, Proliferating trichilemmal cysts are distinguished by trichilemmal keratinization, which is the sudden change from nucleated epithelium to anucleated keratinized cells without a granular layer.

[4] The differential diagnosis include trichilemmal cyst and Turban tumor.

[5] Surgical excision is the treatment of choice for proliferating trichilemmal cysts.