Papillary cystadenocarcinoma is relatively rare among salivary gland tumors, accounting for approximately 5-7% of salivary gland epithelial tumors, and is often considered a subtype of adenocarcinoma. Eneroth et al. referred to this type of tumor as "mucus-producing adenopapillary carcinoma." Papillary cystadenocarcinoma originates from the epithelial cells of salivary gland ducts.

bubble_chart Pathological Changes

(1) Gross Morphology The tumor resembles a mixed tumor in appearance, presenting as round or nodular, mostly without a membrane. The tumor section often reveals cystic cavities with an irregular inner wall, which may have some papillary projections or a granular appearance.

(2) Microscopic Examination The cancer cells vary in size, appearing columnar or cuboidal, and form various irregular glandular structures, many of which are significantly dilated to form cystic spaces. The cells are arranged disorderly, either in a single layer or multiple layers, with marked hyperplasia of cancer cells forming single or branching papillae protruding into the cystic cavity. The cytoplasm of the cancer cells is slightly basophilic, and the nuclei are large, polymorphic, deeply stained, and frequently mitotic. Between the cancer cells or within the papillae, there is a small amount of fibrous stromal tissue, often infiltrated by inflammatory cells but lacking lymphoid tissue. The tumor membrane is incomplete, and tumor cells may sometimes be seen invading it or the surrounding tissues.

(3) Biological Characteristics The growth rate of papillary cystadenocarcinoma varies; it can metastasize via blood vessels or lymphatic pathways and may also invade nerves.

Papillary cystadenocarcinoma is most commonly found in the parotid gland, followed by the minor salivary glands of the palate and submandibular gland. It can also occur in the minor salivary glands of the buccal mucosa, floor of the mouth, tongue, upper lip, and other areas. According to a domestic report by Dong Shaozhong, the age of onset ranges from 12 to 72 years, with an average of 42.5 years, and is most prevalent between 30 and 50 years old. The male-to-female ratio is 2:1.

The tumor resembles a malignant mixed tumor, and the most common symptom is a painless local mass that grows relatively quickly. Some may grow quite large and appear nodular. Due to significant dilation of the glandular lumen, cystic formations may develop, and hemorrhage or necrosis can occur, often leading to cystic degeneration. On palpation, parts of the tumor may feel soft, and puncture can yield bloody secretions. In the early stages, there is usually no obvious adhesion, and the mass is mobile. As the tumor grows, mobility gradually decreases, and it may adhere to surrounding tissues, often invading deeper adjacent structures, including the masseter muscle and mandible. In the advanced stage, pain and symptoms related to facial nerve involvement frequently appear.

bubble_chart Treatment Measures

The primary treatment for papillary cystadenocarcinoma is thorough local excision, including the soft tissue and bone surrounding the tumor, which should be removed en bloc. If the tumor occurs in the parotid gland and is adjacent to the facial nerve, the entire parotid gland, tumor, and facial nerve should be excised. Papillary cystadenocarcinoma has a high tendency for lymphatic metastasis; therefore, when enlarged lymph nodes are palpated, a neck lymph node dissection should be performed regardless of whether metastasis is clinically suspected.

The prognosis of papillary cystadenocarcinoma is inconsistent. Some believe it grows slowly, metastasizes late, and is of low malignancy; others argue that this tumor has a very high rate of lymphatic metastasis, metastasizes relatively early, and has a poorer prognosis. Some suggest its prognosis lies between adenoid cystic carcinoma and mucoepidermoid carcinoma. According to Eneroth's report, the 5-year survival rate is 78%, and the 20-year survival rate is 41%. Domestically, Dong Shaozhong reported a 5-year survival rate of 58.6%.