Step 1: When a lump arises within the parotid and feels firm yet partly soft, the examiner is pointing toward a tumour with heterogeneous tissue architecture. Step 2: Pleomorphic adenoma fits perfectly. The word pleomorphic describes the mixture of epithelial sheets, myoepithelial cells and a mucoid or cartilage like matrix, not just varied appearance. This mix is what produces the uneven feel. Step 3: It is the single most common salivary gland neoplasm and overwhelmingly favours the parotid, presenting as a painless lobulated mass. Step 4: Sebaceous cyst and dermoid cyst are dermal cystic lesions; neither is a genuine parotid parenchymal tumour, so the combined option is also wrong. \[\boxed{\text{Pleomorphic adenoma}}\]