Cyst: a nodule consisting of liquid or semi-solid material surrounded by a capsule located in the dermis. Pseudocyst is different due to lack of capsule/epithelial wall.
May appear anywhere on body; can be solitary, localized or disseminated.
May progress to infection, necrosis, ulcer or scar.
Epidermoid cyst, trichilemmal cyst, hidradenitis suppurativa, severe acne.
Retention of secretions (epidermoid cyst/trichilemmal cyst).