Trichilemmal Horn: A Case Report

Trichilemmal horn or trichilemmal keratosis is a benign neoplasm, that occurs more frequently in females and in the age group over 50 years old. Clinically, it presents as a cutaneous horn and histologically shows trichilemmal keratinization at the base of the lesion.As an uncommon pathology, in this case report, we will present the case of a young man (14 years old), presenting a keratotic lesion on the forehead for eight months, which revealed the diagnosis of trichilemmal horn after lesion exeresis and anatomopathological analysis.

Case Report and Highlight Clues on the Diagnosis of Pilomatrical Carcinoma

Pilomatrical Carcinoma (PC) is a rare malignant adnexal tumor with matrical differentiation. Its benign counterpart (Pilomatrixoma) is diagnosed much more frequently in daily pathological practice. Both entities share genetic alterations but the malignant counterpart acquires mutations that make it develop an aggressive behavior [1]. We describe a 33-year-old man who presented with a 7 x 6 cm nodular ulcerated lesion in the left ear with markedly accelerated growth in the last month. Incisional biopsy was referred to us with suspicion of squamous cell carcinoma versus pyogenic granuloma. Histologic sections showed ulcerated fragments infiltrated by a basaloid cell proliferation interspersed with groups of “ghost cells”. The neoplastic cells were arranged in irregular sheets with infiltrative borders. Groups of Squamous cells with trichilemmal keratinization and foci of necrosis were also identified. The biopsy was diagnosed as an adnexal neoplasm with pilomatrical differentiation, suggesting its complete resection with safety margins due to the presence of aggressive characteristics. The subsequent study of the excisional biopsy showed similar characteristics to those previously described. Notoriously, focal infiltration of the auricular cartilage was identified, leading us to the undoubted diagnosis of pilomatrical carcinoma.

Onycholemmal Horn: An Exceedingly Rare Subungual Tumor

The onycholemmal horn is an exceedingly rare subungual tumor characterized by trichilemmal-like keratinization pattern. The only previous instance of onycholemmal horn dates back to 1983 when Haneke reported a keratotic subungual tumor clinically and histologically comparable to a trichilemmal horn. No other case of this condition has been reported so far. We present the case of a 72-year-old female patient, with a history of a slowly growing tumor originating from the nail bed epithelium of the left thumb. The lesion was surgically removed, and pathological examination was consistent with the diagnosis of an onycholemmal horn. Additionally, this study aims to elucidate the correlation between the onycholemmal and trichilemmal keratinization.

BENIGN PROLIFERATING PILAR TUMOUR OF THE ELBOW – A RARE CASE REPORT

Benign proliferating pilar tumour also known as proliferating trichilemmal cyst is a rare tumor usually occurring on the head and neck region of elderly women and its pathognomonic feature is trichilemmal keratinization. Here, a 65 year old elderly female presented to us with a benign proliferating pilar tumour of the right elbow for the past 6 months for which wide local excision and a local flap was used to cover the post excisional defect. This should be differentiated from trichilemmal cyst as it has potential for malignant transformation. Thus, complete excision is recommended for all benign proliferating variants owing to their potential for locally aggressive behavior and malignant transformation.