Malignant papillary cystadenoma lymphomatosum. Light and electron microscopic study

Salivary Duct Carcinoma Arising in a Warthin Tumor of the Parotid Gland: A Rare Case Report with Review of Literature and PD-L1 Expression

Warthin's tumor is the second most common neoplasm of the parotid gland and consists of 2 components, including lymphoid stroma and glandular epithelium. Malignant transformation in this tumor is mostly seen in the lymphoid component; however, the carcinomatous transformation of the epithelial component is extremely rare. Cases of latter reported in the literature include squamous cell carcinoma, adenocarcinoma, mucoepidermoid carcinoma, oncocytic carcinoma, Merkel cell carcinoma, and undifferentiated carcinoma. We describe an extremely rare case of salivary duct carcinoma arising in a Warthin tumor in a 64-year-old male. Patient presented with an enlarging left parotid mass, biopsy of which showed salivary duct carcinoma. He subsequently underwent left parotidectomy along with left level II-IV lymph node dissection. Histology revealed both in situ as well as invasive salivary duct carcinoma arising from Warthin tumor. Immunohistochemistry showed tumor cells positive for CK7, AR, and GATA3, while p63 highlighted the myoepithelial cell layer in the in situ component. Her2 was 2+ by immunohistochemistry. In addition, PD-L1 IHC revealed positive expression with a combined positive score of 20%.

Primary Merkel cell carcinoma of the parotid gland

Primary Merkel cell carcinoma (MCC) is a neuroendocrine tumor that typically affects older whites. It usually originates in the dermis, but in rare instances it has arisen in other primary sites, including the oral mucosa and the parotid gland. Explanations for the presence of MCC in these atypical locations have included theories of malignant transformation and neuroendocrine migration. We describe the case of a 35-year-old white woman who had an MCC in the parotid gland and no evidence of any other primary cutaneous lesion. A left superficial parotidectomy with facial nerve preservation was performed, and a histologic diagnosis of MCC was made. Positron-emission tomography was negative for other lesions, and postoperative radiation therapy was administered for local control. To the best of our knowledge, this is only the sixth case of a primary MCC of the parotid gland to be reported in the English-language literature; of these 6 patients, ours was by far the youngest. Otolaryngologists should be familiar with this rare but potentially fatal neoplasm.

Merkel cell carcinoma of the parotid gland associated with Warthin tumour: report of two cases

AIMS

Two cases of Merkel cell carcinoma occurring simultaneously and in close association with a Warthin tumour of the parotid gland are reported.

METHODS AND RESULTS

The patients were a 65-year-old man and a 70-year-old man, respectively. The Merkel cell carcinoma component was immunoreactive for chromogranin and keratin 20 and contained neuroendocrine-type granules at the ultrastructural level.

CONCLUSIONS

The histogenesis of this heretofore undescribed combination is discussed.

Mucoepidermoid carcinoma arising in Warthin's tumour of the parotid gland: report of two cases with histopathological, ultrastructural and immunohistochemical studies

AIMS

Malignant transformation of Warthin's tumour (WT) is a rare event. We present two cases of mucoepidermoid carcinoma (MEC) arising in WT in the parotid gland.

METHODS AND RESULTS

Two cases of MEC arising in WT, which were found in 185 cases of WT of the parotid gland, were investigated by light and electron microscopy, and immunohistochemistry. Both cases had largely similar macroscopic and histological features with some differences. Histologically, the tumours consisted mainly of WT with multilayered hyperplastic arrangements of oncocytic cells and focal squamous and goblet cell metaplasia. In the same tumour mass, however, the features of MEC were observed with invasion to adjacent adipose tissue. A transitional zone between WT and MEC was evident. Both patients were alive and well without evidence of recurrence 30 and 34 months after surgery, respectively. Electron microscopy revealed that cyst lining epithelial cells in WTs had abundant mitochondria whereas some of the MEC cells contained numerous tonofilaments and mucinous granules. Immunohistochemically, oncocytic cells of WTs were strongly positive for mitochondria and SalylTn was extensively stained in MECs. The labelling index for Ki67 was obviously higher in the carcinoma cells than the epithelial cells of WT.

CONCLUSIONS

Our cases confirmed the possibility of malignant transformation of the epithelial component in WT to MEC.

Carcinoma in basal cell adenoma of the parotid gland

Malignant transformation of basal cell adenoma (BCA) of the parotid gland is rarely reported, and when occurred, may principally become manifest as a malignant basaloid tumor, i.e. basal cell adenocarcinoma or adenoid cystic carcinoma. We describe herein three cases of non-basaloid carcinoma arising in BCA. The incidence of this malignant tumor was 0.2% of all parotid gland tumors and 4.3% of BCAs in our series. One case was salivary duct carcinoma showing histologic evidence of transition between malignant and benign elements. The remaining two cases were well-encapsulated parotid gland tumors, which were composed of BCA and scattered foci of malignant transformation. Malignant components were adenocarcinoma, not otherwise specified (NOS), and sometimes intermixed with neoplastic myoepithelial cells included BCA cells. These two cases were regarded to be intracapsular carcinoma in BCA. BCA components showed solid, tubular and trabecular arrangements. The patients' prognosis was quite variable among these three cases; the first case died of disease after 27 months, whereas the latter two cases are alive and well for 4 and 10 years after surgery. Ki-67 labeling index indicated that cell proliferative activity was at least five times higher in carcinomas than BCAs. Non-basaloid carcinomas such as salivary duct carcinoma or adenocarcinoma, NOS, do develop in BCAs as in the case of a pleomorphic adenoma with malignant transformation, though the incidence may be extremely rare.

Epidermoid carcinoma arising in Warthin's tumour: a case study

We present a case of epidermoid carcinoma arising in Warthin's tumour of parotid gland in an 80-year-old woman. Light microscopy revealed small foci typical of benign Warthin's tumour with transition to epidermoid carcinoma. Immunohistochemical and ultrastructural observations confirmed the epidermoid features of the malignant cells. The differential diagnosis of a metastasis from an epidermoid carcinoma to the stroma of Warthin's tumour and also of the so-called metaplastic variant of Warthin's tumour is discussed.

Warthin's tumor-associated neoplasms: report of two cases and review of the literature

The association of Warthin's tumor with another neoplasm of a different histological type in the same salivary gland is extremely rare. The literature includes 42 such cases to date. A case of malignant lymphoma developing within Warthin's tumor and another case of oncocytoma synchronous with Warthin's tumor in the same parotid gland are reported. The relation of Warthin's tumor to other neoplasms is discussed.

Malignant Warthin's tumour: a case study

Malignant transformation of a benign Warthin's tumour (adenolymphoma) is extremely rare. The light microscopic and ultrastructural features of an adenocarcinoma arising in a Warthin's tumour in the parotid gland are described. Light microscopy demonstrated a transition zone from the benign to the malignant component, and the malignant cells revealed oncocytic features by both light- and electronmicroscopy.