The nature of what exactly is a cyst on the left hand usually depends on the location of its occurrence and its clinical presentation. Generally speaking, if it occurs in superficial tissues such as the arm, the common diseases are mainly epidermoid cysts or sebaceous cysts. In the case of sebaceous cysts, there is a possibility of secondary infection or even abscess formation, and usually surgical excision of either epidermoid cysts or sebaceous cysts is performed after the diagnosis is clear. Another more common disease is cysts that occur in the finger joints, usually tendon sheath cysts, especially in the wrist or finger joints, which usually require reduced activity to reduce tissue production in the joint cavity. If the cyst does not resolve after symptomatic treatment such as rest, surgical removal is usually required, but is prone to recurrence.