Proliferating trichilemmal tumour: a comparison of dermoscopic, ultrasonographic and histopathological features

Proliferating trichilemmal tumour (PTT) is a rare and usually benign dermal or subcutaneous neoplasm. Some PTTs are difficult to clinically diagnose since the clinical differential diagnoses of PTT range from benign conditions, such as epidermal cyst, to malignant skin tumours, such as basal cell carcinoma(BCC), squamous cell carcinoma (SCC), and malignant PTT [1-3]. The lack of distinguishing dermoscopic and sonographiccharacteristics of PTT reported in the literature prompted us to report a case [...]