Carcinoma ex pleomorphic adenoma of the upper lip

Abstract

Carcinoma ex pleomorphic adenoma (CXPA) is a rare salivary gland malignancy most often reported within the parotid gland. Of the salivary gland tumours that occur within the minor salivary glands at least 50% are reported to be malignant. This proves to be inaccurate when describing salivary gland tumours within the upper lip which are usually benign. A Medline search of the English language literature yields only one case report of a CXPA located within the upper lip. The authors present a second case report of CXPA within the upper lip and a review of its pathologic features and management.

Salivary gland tumours account for approximately 3% of all head and neck tumours. Of tumours arising within the minor salivary glands, pleomorphic adenoma is considered to be the most common benign variant. It typically presents as a slow growing, painless mass located on the palate. There is a 2–4% malignant transformation rate in tumours that are long standing, most occurring within the parotid gland . In a series of 380 intra-oral minor salivary gland tumours only 1.3% of malignant cases and 0.5% of all salivary gland tumours reported were carcinoma ex-pleomorphic adenoma (CXPA) . In case reports, CXPA within the oral cavity is most often located within the palate. A medline search of the English language literature using mesh terms carcinoma ex-pleomorphic adenoma, upper lip and minor salivary gland yield only one case report . The authors report a new case involving CXPA of the upper lip.

Case report

A 72-year-old African American male presented to the Oral & Maxillofacial Surgery service with a history of a painless lump in the labial sulcus of the left upper lip. The patient reported the lesion had been present for approximately 5 years. The mass had grown slowly over time and was now preventing the proper fit of his maxillary denture. No other symptoms were reported. The patient’s medical history included hypertension, type II diabetes mellitus and hypercholesterolemia, all of which were medically controlled.

On clinical examination, the mass was 2 cm × 2 cm with intact overlying mucosa within the labial mucosa of the left upper lip ( Fig. 1 ). There was no palpable cervical lymphadenopathy. An MRI scan of the head and neck showed a well demarcated 2.2 cm × 2.4 cm mass with high intensity signal on T2 imaging localized in the left upper lip ( Fig. 2 ).

Fig. 1
Raised mass in the labial mucosa of the upper lip measuring approximately 2 cm × 2 cm.

Fig. 2
MRI T2 axial image with gadolinium demonstrating a well-defined tumour within the upper lip with high signal uptake as compared to the surrounding muscle.

Pathologic diagnosis, established with an incisional biopsy performed under local anaesthesia, demonstrated a pleomorphic adenoma. The patient agreed to excision of the salivary gland tumour and local flap reconstruction. Intra-operatively the overlying mucosa was also excised with an extracapsular dissection of the salivary gland tumour. The defect was closed with local rotational advancement flaps. Final pathology reported a completely excised tumour with regions indicating malignant transformation including perineural invasion within the capsule, consistent with CXPA. The multidisciplinary Head & Neck tumour board decided that no adjuvant therapy was necessary since the tumour was in a location amenable to easy observation and had been completely excised with clear margins without evidence of extra-capsular extension. The patient has had no evidence of disease recurrence for the past 8 months.

Histology

Grossly, the specimen consisted of a 2.4 cm × 2.1 cm × 1.5 cm, firm, white-tan, focally haemorrhagic mass that appeared to abut the inked margins. The mass was homogeneous and well-circumscribed.

Histologically the tumour was composed of nests and sheets of epitheloid cells with abundant light pink cytoplasm and round to oval nuclei with fine chromatin and inconspicuous nucleoli. The nests and sheets were separated by thin bands of fibrous stroma containing small capillaries. Additionally, small islands of cartilaginous and myxoid matrix were present within the tumour. Rare mitotic figures were present (up to 2 per high power field). Myoepithelial cells with vacuolated cytoplasm and smaller, dark round nuclei were also present in small numbers throughout the tumour. There were also areas containing scant amounts of myxoid type stroma and cells. The periphery of the tumour showed several small foci of perineural invasion, with tumour cells similar to those described above, invading and surrounding small nerve fibres. There was no evidence of extra-capsular extension. Immunohistochemical stains (S-100, Vantana, clone 4C4.9, lot number 812854, pre-diluted; Ki-67, Vantana, clone 30-9, lot number 1302558, pre-diluted; p63, Vantana, clone 4A4, lot number 1302558, pre-diluted; Actin, Vantana, clone HUC1-1, lot number 24108, pre-diluted; all immunostains performed on the Vantana Benchmark XT Autostainer) showed, as expected positive S-100 staining both in the epithelial cells as well as in the small nerves. Ki-67 was positive in less than 5% of the epitheloid cells. Actin and p53 immunostains were mostly negative ( Figs. 3 and 4 ).

Fig. 3
Low power, haematoxylin–eosin (H–E) stain of the salivary gland tumour showing encapsulation of the main tumour mass (arrows) as well as adjacent benign salivary gland, fibrous tissue and overlying squamous mucosa (arrow heads). The previous biopsy site is also evident (open arrowheads). The microscopic foci of perineural invasion at the periphery of the tumour are not appreciated at this magnification.

Jan 26, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Carcinoma ex pleomorphic adenoma of the upper lip
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