A malignant neoplasm made up of abnormal germinative cells analogous to those that compose the folliculosebaceous-apocrine germ in an embryo and that usually manifests clinically as a papule or nodule which may become ulcerated.
An inflammatory process that develops secondary to trauma, usually in the form of a penetrating injury or rupture of a follicle, and that proceeds through stages of granulation tissue with numerous extravasated erythrocytes, granulomatous inflammation, and fibrosis.
A malignant nonepithelial neoplasm (a sarcoma) presumably of perineural fibrocytes that presents itself usually on the trunk, but sometimes elsewhere, such as the extremities, face, and scalp.
A hamartoma of mostly follicular elements that presents itself clinically as a firm, skin-colored papule.
Infundibulitis, usually a suppurative inflammatory process that involves infundibula, is either noninfectious, as in the case of pustules of acne vulgaris, or infectious, as in the case of pustules caused by Staphylococcus aureus.
A constellation of lesions that represent disorders of melanocytes (e.g., axillary “freckles” and café au lait “spots”) and of proliferations of Schwann cells (e.g., papules, nodules, and tumors of neurofibroma).
An inflammatory process in pregnant women near term that consists of urticarial papules and plaques, especially on the trunk and particularly in association with lesions of striae atrophicantes, the lesions disappearing shortly after parturition.