Case of Malignant Proliferating Trichilemmal Tumour in Gluteal Region

Abstract

Malignant Proliferating Trichilemmal Tumour (MPTT) is a rare, malignant cutaneous adnexal tumour that originates from the outer root sheath cells of the isthmus of hair follicles. This article aims to report a rare case of a high-grade malignant trichilemmal tumour arising in the context of a proliferating Trichilemmal Cyst (TC) in a 65-year-old female who presented with a painless swelling in the left gluteal region that had been present for two months. There have been only about 100 cases reported so far. Both the clinical features and the imaging findings were suggestive of an ostensibly benign lesion. As a result, the cyst was excised; however, further histopathological evaluation revealed an unexpected case of rare MPTT. Consequently, a timely second revision surgery was performed to ensure tumour-free margins. This case illustrates that the diagnosis of MPTT is highly challenging. Without prior knowledge and a high index of suspicion, the diagnosis of MPTT could easily be missed. MPTT is often misdiagnosed as a variant of Squamous Cell Carcinoma (SCC). The subtle nuances of the unique histopathological pattern of MPTT can help differentiate it from SCC.

Keywords

• malignant transformation
• skin adnexal tumour
• trichilemmal cyst