Adenoid Cystic Carcinoma Key Points Adenoid cystic carcinoma (ACC) is an epithelial tumor that occurs primarily in the major salivary and lacrimal glands, and the skin can be involved secondarily…

Angiosarcoma Key Points Angiosarcoma is a rare aggressive malignant tumor of vascular origin About 62% occur in the head and neck region, more common in men in the 6th to…

Xanthogranuloma and Histiocytoses Key Points The pathogenesis of xanthogranulomas is unknown, but it is believed that they arise from a reactive, metabolic, or inflammatory process that results in the proliferation…

Xeroderma Pigmentosum Key Points Xeroderma pigmentosum (XP) is an autosomal recessive hereditary disease It is a congenital sensitization of the skin to ultraviolet radiation, due to a defect in normal…

Verruca Vulgaris Key Points Verruca vulgaris (common wart) is a benign growth in the epidermis caused by localized infection with one of the many types of human papillomavirus (HPV) HPV…

Xanthelasma Palpebrarum Key Points Xanthelasma is a condition characterized by the development of flat yellowish papules or plaques near the medial canthal region in the upper or lower eyelids or…

Trachoma Key Points Trachoma is a chlamydial infection characterized by recurrent episodes of conjunctival inflammation with lymphoid follicles and, in some cases, severe papillary hypertrophy Chlamydial antigens are believed to…

Syringoma Key Points Syringoma is a benign adnexal tumor derived from the intraepidermal eccrine duct It can be associated with several systemic syndromes including diabetes mellitus, Down syndrome, Brooke-Spiegler syndrome,…

Syringocystadenoma Papilliferum Key Points Syringocystadenoma papilliferum (SCAP) is a benign adnexal skin tumor presenting as a proliferating lesion of apocrine, eccrine, or pluripotential appendageal cells, mostly located on the head…

Stevens-Johnson Syndrome Key Points Stevens-Johnson syndrome (SJS) is a severe T-cell-mediated, usually drug-induced, acute blistering disease of the skin SJS, together with toxic epidermal necrolysis, represents a wide spectrum of…