Two Cases of Malignant Proliferating Trichilemmal Tumors: Large Tumors on the Scalp without Metastasis / 대한피부과학회지

ABSTRACT

Proliferating trichilemmal tumor (PTT) is an uncommon neoplasm originated from the outer root sheath of a hair follicle. Malignant transformation occurs occasionally in proliferating trichilemmal tumors, which can be manifested by sudden rapid growths. Histologically, the malignant proliferating trichilemmal tumors (MPTTs) have shown severe nuclear atypia, marked cellular pleomorphism with atypical mitoses, dyskeratotic cells and infiltrating margins. Squamous cell carcinoma (SCC) should be differentiated with MPTT which indicates characteristic trichilemmal keratinization. Large tumor is considered as a risk factor of metastasis in SCC, but the relationship between tumor size and metastasis in the MPTT is not yet clarified. In this report, two patients have large erythematous nodules with focal ulceration and necrosis on their scalps and were diagnosed as MPTT. Despite the large sizes of the tumors, there were no evidences of metastases. Herein, we report 2 cases of the large MPTT which are presented without metastasis.