An extremely rare salivary gland tumor: intraductal carcinoma of the buccal mucosa

Abstract

Intraductal carcinoma of the salivary gland is a rare, indolent neoplasm characterized by intraductal malignant cell proliferation but lacking invasiveness, in contrast to conventional salivary duct carcinoma, a clinically aggressive neoplasm with invasive characteristics. The tumor affects the major salivary glands much more frequently than the minor salivary glands. This report describes an extremely rare intraductal carcinoma arising from the buccal mucosa in a 61-year-old man who presented with a painless mass in the left buccal mucosa, which he had had for 1 month. A biopsy of the tumor indicated it was most likely an adenocarcinoma, but accurate preoperative diagnosis was difficult. The tumor was completely removed, along with sufficient margins. Histological examination revealed that the lesion was composed of proliferating epithelial cells surrounded by an intact myoepithelial layer, with no evidence of invasion. The final diagnosis was intraductal carcinoma of the salivary gland. No recurrence has been observed for over 3 years. In conclusion, the difficulty in preoperatively diagnosing this rare entity suggests that complete surgical excision with sufficient margins remains the best treatment option.

Salivary Gland Intraductal Carcinoma: How Do 183 Reported Cases Fit Into a Developing Classification

“…Suffice it to say, cystadenoma (including oncocytic subtype), sclerosing polycystic adenoma, intercalated duct adenoma, and striated duct adenoma are the benign tumors, whereas secretory carcinoma and SDC, along with cystadenocarcinoma, acinic cell carcinoma, and oncocytic patterns seen in other neoplasms, are the most important malignant neoplasms to be considered. No matter what the differential considerations raised, the most significant evaluation must include documentation of myoepithelial cells by IHC, and further to document their presence or absence as part of the evaluation of frankly invasive carcinoma 6,12,24,31,70,78,87–89. Furthermore, it is significant that there is remarkable overlap between apocrine-type IDC arising in a sclerosing polycystic adenoma and apocrine type IDC; some secretory carcinomas may show significant overlap that requires molecular studies for a more definitive diagnosis; and invasive SDC may be indistinguishable from destructively invasive apocrine type IDC 37,41,90.…”

“…No matter what the differential considerations raised, the most significant evaluation must include documentation of myoepithelial cells by IHC, and further to document their presence or absence as part of the evaluation of frankly invasive carcinoma. 6,12,24,31,70,78,[87][88][89] Furthermore, it is significant that there is remarkable overlap between apocrine-type IDC arising in a sclerosing polycystic adenoma and apocrine type IDC; some secretory carcinomas may show significant overlap that requires molecular studies for a more definitive diagnosis; and invasive SDC may be indistinguishable from destructively invasive apocrine type IDC. 37,41,90 Finally, when there is exclusively intralymph node involvement of an IDC, it should not be misdiagnosed as metastatic carcinoma or melanoma.…”

Intraductal Carcinoma: The Carcinoma In Situ of the Salivary Gland

“…The morphological and behavioral features of IDC differ from the more aggressive SDC 4 as all the subtypes tend to be indolent and rarely have the ability to metastasize. As a result, it has a better prognosis and higher chance of cure after excision 5 .…”

“…1 It was initially described as a variant of salivary duct carcinomas (SDCs) by Delgado et al 2 in 1996 and reclassified in the fourth edition of the World Health Organization classification of head and neck tumors in 2017 from "low-grade cribriform cystadenocarcinoma" to "IDC" with low-grade and high-grade phenotypes. 3 The morphological and behavioral features of IDC differ from the more aggressive SDC 4 as all the subtypes tend to be indolent and rarely have the ability to metastasize. As a result, it has a better prognosis and higher chance of cure after excision.…”