vesicle, pouch, hernial sac, saccule, sacculus, cystostomy, cavity, cysticule, sinus, outpocketing, more...

tumor, growth, swelling, lesion

sebaceous, epidermoid, dermoid, pilar, follicular, cystic, dermal, subcutaneous, more...

ovarian, large, dermoid, aneurysmal, simple, dentigerous, choledochal, small, renal, thyroglossal, sebaceous

animal's blister,   fluid-filled sac,   fluid filled sac,   squishy lump