Unusual variants of trichilemmal tumors – Report of two cases with review of literature

ABSTRACT: Trichilemmal tumors are rare dermal neoplasms derived from the outer root sheath of hair follicles, showing a follicular differentiation on histology and are categorized into benign and malignant entities. Usually presenting as solitary lesions, they have a predilection for women in the fourth to eighth decades of life, with the scalp being the most common site of occurrence. In this article, we report two extremely rare cases, one diagnosed as malignant proliferating trichilemmal tumor with sarcomatous differentiation (MPTT-S) and the other as proliferating trichilemmal cyst with foci of carcinoma in situ (PTC-CIS). These tumors, thus, reveal a spectrum of unusual trichilemmal tumors with similar clinical presentations but contrasting histopathological characteristics. Squamous cell carcinoma is a close differential diagnosis of these lesions; hence, a higher degree of awareness is a requisite for an accurate understanding and diagnosis, as both of them have distinct prognoses and treatment options.