Hidradenitis suppurativa (acne inversa or Verneuil disease) is a chronic inflammatory skin condition of follicular occlusion with lesions including deep-seated nodules and abscesses, draining skin tunnels (also called sinus tracts or fistulae), and fibrotic scars. These lesions most commonly occur in intertriginous areas, though they may present in any location with folliculopilosebaceous units. The most commonly affected areas are the axillary, groin, perianal, perineal, and inframammary regions (see . Hidradenitis Suppurativa, Left Axilla). Treatment varies based on severity and may include topical and systemic antibiotics, hormone therapy, immune modulators, and surgery. This condition may have a negative psychosocial impact because of the associated pain, involvement of sensitive locations, drainage, odor, disfigurement, and scarring. Late diagnosis only worsens the patient experience. Skin appendages include the pilosebaceous units, sweat glands, and nails, which possess distinct functions and histological features. The pilosebaceous unit is the assembly formed by the hair shaft, follicle, sebaceous gland, and arrector pili muscle. This group of skin appendages develops from the epidermis during fetal development. The hair shaft is visible on the skin's surface and is comprised of cuticle cells surrounding a cortex, with a medulla present in thicker hair. The hair follicle is essential for hair growth and is histologically divided into the infundibulum, isthmus, and inferior segment, with stem cells residing in the bulge area. Sebaceous glands are pilosebaceous unit components that produce sebum to lubricate hair. These glands have a foamy appearance microscopically due to their lipid content. Sweat glands (sudoriferous glands) are categorized as eccrine or apocrine, which differ in their distribution and secretion mode. Eccrine glands are present in the dermis and upper hypodermis throughout the body and exhibit merocrine secretion, where the cytoplasm remains intact during secretion. Apocrine glands are found in the dermis and subcutanous fat in areas like the intertriginous zones. These glands lose the top portions of the cellular cytoplasm during secretion. Histologically, eccrine glands consist of coiled secretory segments surrounded by myoepithelial cells, while apocrine glands have less coiling and larger lumens lined by cuboidal epithelial cells. Nails consist of the nail plate, matrix, eponychium, hyponychium, nail folds, and lunula. The matrix serves as the site of nail formation. The nail plate is composed of compact keratinocytes and lacks desquamation, contributing to its rigidity and translucency. The hyponychium lies beneath the nail plate, lacks a granular layer, and contains a rich vascular network. The eponychium serves as a pathogen barrier.