Low Grade Intraductal Carcinoma of Palate: An Extremely Rare Entity with Review of Literature

Low-grade intraductal carcinoma (LG-IDC) is the new World Health Organization designation for tumors previously called "low-grade cribriform cystadenocarcinoma" and "low-grade salivary duct carcinoma". LG-IDC is a rare low grade malignant salivary gland neoplasm. A 56-year old woman presented with a painless swelling on the right posterior part of palate of 2 months duration. Radiographic examination revealed heterogenously enhancing soft tissue mass on right side of palate. A provisional diagnosis of pleomorphic adenoma was executed and local excision was done. The tumor had a typical feature of intraductal growth pattern composed of low grade ductal epithelial cells with cribriform and micropapillary patterns forming true "Roman bridges". Immunohistochemically myoepithelial cells displayed p63 around all tumor islands. The case was diagnosed as LG-IDC. LG-IDC is an extremely rare entity and awareness of this entity is important to avoid erroneous diagnosis and inappropriate treatment.

Low-Grade Intraductal Carcinoma of the Parotid Gland: A Case Report and Literature Review

Low-grade intraductal carcinoma is a rare neoplasia with an excellent prognosis, previously classified as low-grade cribriform cystadenocarcinoma and low-grade salivary duct carcinoma. The tumor mainly occurs in the parotid gland and presents a ductal phenotype and an intraductal/intracystic growth pattern. It resembles intraductal breast lesions such as atypical ductal hyperplasia, papillary and cribriform ductal carcinoma in situ. Despite its infrequency, discriminating low-grade intraductal carcinoma from other salivary gland tumors is crucial, especially because of its favorable prognosis. A 74-year-old woman with a history of neurofibromatosis underwent a superficial parotidectomy to remove a sharply demarcated multi-cystic mass, diagnosed as category 4 at FNAC. The histological examination revealed a demarcated but unencapsulated lesion composed of a bigger cyst surrounded by several smaller cysts, lined by a monolayer or bilayer epithelium alternated with a cribriform proliferation, characterized by "Roman-bridges", with occasional micro-papillae. A myoepithelial component, with a basal disposition, was present, confirmed by intense staining for protein p63 and SMA. Immunohistochemical stains showed intense, strong uniform positivity for pan-cytokeratin, protein S100, and SOX10. The Ki67 proliferation index was low (< 10%). A diagnosis of Low-grade Intraductal Carcinoma (LGIC) of the parotid was made. We performed a literature search in PUBMED for "Intraductal carcinoma", "Low-grade Intraductal Carcinoma", "Cribriform Cystadenocarcinoma", "Salivary Duct Carcinoma", and "Low-Grade Salivary Duct Carcinoma". We selected 17 papers published between 1983 and 2020; the most affected anatomical site was the parotid gland (77/90), followed by minor salivary glands (6/90), the intraparotid lymph nodes (3/90) and the submandibular gland (4/90). Their main histopathological features are reported in the paper. Here we present a case report and a review of scientific literature on this topic to provide some essential diagnostic tools to discriminate this rare entity.

Low-grade intraductal carcinoma of salivary glands: A systematic review of this rare entity

Background

Low-grade intraductal carcinomas are rare, malign tumors of salivary glands most commonly affecting parotid gland. It is a slow-growing tumor considered with a favourable prognosis after surgical excision.

Methods

To define the characteristics and management of low-grade intraductal carcinoma a systematic review was performed using the electronic databases Pubmed, Cochrane and Scopus. A new case report was also described.

Results

Including this case the review of literature identified only 54 cases reported thus far. Demographics, clinical presentation, diagnostic tools, treatment, follow-up and recurrence rate, histological and immunohistochemical patterns of this kind of tumor were summarized.

Conclusion

Low-grade intraductal carcinoma has already been well defined but is important to focus on the fact that in few cases component of high-grade infiltrations have been reported: this may modify surgical approach because a simple tumorectomy may not be enough.

Epithelial proliferation in small ducts of salivary cystadenoma resembling atypical ductal hyperplasia of breast

Salivary gland cystadenomas are cystic neoplasms with diverse architecture and cytology. Cystadenomas may have a considerable intracystic epithelial component, but an epithelial proliferation in small ducts and cysts resembling atypical ductal hyperplasia of breast has not been documented. The patient was a 68-year-old man with a slow growing right submandibular mass. He has no recurrence 13 months after resection. The tumor was polycystic and measured 3.0 x 2.5 x 2.5 cm. The epithelium of the larger cysts was composed of flat, cuboidal, columnar, and apocrine-like cells. Many of the larger cysts showed "Roman bridges", epithelial tufting, and papillae. The smaller cysts and ducts had apocrine-like cells forming secondary glandular lumens. The ductal cells were surrounded by clear myoepithelial cells. Nuclear pleomorphism and hyperchromasia was seen in the apocrine-like cells. Adjacent to the larger cysts, there was an adenomatoid proliferation of small ducts surrounded by myoepithelial cells. No mitotic activity, necrosis, or stromal invasion was identified. The ductal cells were diffusely positive for keratin 7 and androgen receptors with focal expression of keratin 19 and high-molecular weight keratin. S-100, estrogen and progesterone receptors, and BRST-2 were negative in the ductal cells. Recognition of a prominent intraductal epithelial component in cystadenomas is important to avoid a misdiagnosis of cystadenocarcinoma or low-grade salivary duct carcinoma. Cystadenomas join the list of salivary gland lesions with microscopic similarities to primary lesions of the breast.