Clear cell carcinoma arising in pleomorphic adenoma of the minor salivary gland

Salivary gland myoepithelial carcinoma

Salivary gland myoepithelial carcinoma (MC) or malignant myoepithelioma is a rare entity. MC usually presents as a slow-growing painless mass arising in the parotid gland, but may involve other salivary glands. This tumour may be particularly locally aggressive, but its clinical and biological features are not yet fully understood. MC may arise from pre-existing benign lesions, such as pleomorphic adenomas or benign myoepitheliomas, or may arise de novo. It usually affects patients over 50 years old, with no gender preference. Because it is often asymptomatic, the presentation and diagnosis can be delayed by months, even years. The current WHO classification considers MC to be an intermediate- to high-grade malignancy. Other published data suggest it is likely to be a high-grade neoplasm, consistent with its aggressive behaviour. Its epidemiology, histopathological features, immunohistochemical profile, clinical behaviour and optimal management are not well understood. Following review of the current literature we aim to address these.

Clear cell carcinoma: review of its histomorphogenesis and classification as a squamous cell lesion

In current classification schemes, clear cell carcinoma-including both the hyalinized and nonhyalinized variety--is now an accepted subtype of malignant salivary gland tumors. Despite this, the underlying cellular differentiation process leading to the typical histomorphology of this neoplasm remains unclear. This review summarizes and illustrates the histologic, ultrastructural, and immunohistochemical evidence for the underlying squamous cell nature of clear cell carcinoma. Squamous cell differentiation is not an uncommon feature of nonneoplastic and neoplastic lesions of the salivary glands. Clear cell carcinoma needs to be added to this list as a unique but specific variety of clear cell squamous carcinoma.

Fine-needle sampling findings in 26 carcinoma ex pleomorphic adenomas: diagnostic pitfalls and clinical considerations

Preoperative fine-needle samplings (FNS) of 26 histologically proven carcinoma ex pleomorphic adenomas (24 primary tumors and 2 local recurrences in 24 patients) were retrospectively reviewed in order to evaluate their cytologic characteristics. Histologically, 17 were high-grade and 9 were low-grade carcinomas; 10 carcinomas were intratumoral (in situ), and 16 were infiltrative. A cytologic diagnosis of malignancy was established in 13 (50%) cases, 2 (7.7%) were suspicious, and 11 (42.3%) were negative for malignancy (10 pleomorphic adenomas, 1 inflammation). The majority (76.5%) of high-grade carcinomas were correctly diagnosed by FNS, regardless of invasiveness. Paradoxically, most (77.8%) negative results were encountered in low-grade carcinomas. Accurate diagnosis of malignancy on FNS is achieved in high-grade tumors and low sensitivity may cause interpretative difficulties in low-grade tumors. Diagn. Cytopathol. 1999; 21:163-166.

Clear cell carcinoma of the minor salivary glands. Report of a case

Clear cell carcinoma is an extremely rare form of malignant salivary gland tumour. A case of clear cell carcinoma arising in the minor salivary glands is reported.

Clear cell carcinoma arising in a pleomorphic adenoma of the submandibular gland

Clear cell carcinoma of salivary gland is a rare neoplasm. We report a third case of clear cell carcinoma arising in a pleomorphic adenoma and also in an extraparotid location. We document the immunohistochemical profile of the tumour including reactivity with a marker for the c-erbB-2 oncoprotein and suggest a myoepithelial origin for these lesions. The presence of a tetraploid stemline may account for the rapid tumour progression in this case.

Clear cell neoplasm

We are reporting four cases of clear cell neoplasm. Local infiltration and destruction was observed in one case while in a second case, originating in the sublingual gland, metastasis to the lymph nodes occurred. The behaviour of these neoplasms has prompted the suggestion that these tumours be designated carcinomas rather that noncommittally tumours or neoplasms (Batsakis and Regezzi, 1977). The histopathological characteristics of our four cases conform to those that have been articulated and believed to be the distinctive features of these tumours (Batsakis and Regezzi, 1977). It is hoped that ours and similar reports will be helpful towards clearing the diagnostic and taxonomic confusion regarding these tumours.