Parotid gland keratocystoma: a rare diagnosis of a neck lump

Abstract

Keratocystoma of the parotid gland is a rare benign tumour, with only a handful of case reports in literature. We report a case of a man in his 70s who presented to the head and neck clinic with a 2-month history of a gradually increasing left neck swelling. Fine-needle aspiration showed contents of an epidermal cyst; however, an MRI showed a solid/cystic mass with a low T2 signal, suggesting increased risk of malignancy. The patient went on to have a left superficial parotidectomy and level IIa supraselective neck dissection. The lesion contained laminated keratin and was lined by squamous epithelium, with nodal extension. Features were those of a keratocystoma; metastatic cystic well-differentiated squamous cell carcinoma was not favoured. This is the first reported case of a parotid keratocystoma with nodal extension of the lesion. This case report demonstrates that surgical excision and clinical monitoring can be a safe management strategy for these benign tumours.

Keywords: Head and neck surgery; Pathology.

Figure 1

Ultrasound scan of left parotid gland showing a 2.3 cm heterogeneous mass inferior to the tail of the gland (arrow).

Figure 2

Coronal section of MRI neck (T2-weighted sequence) showing a 2.1 cm heterogeneously enhancing mixed solid/cystic mass in between the deep and superficial lobes of the left parotid (arrow).

Figure 3

Axial section of MRI neck (T2-weighted sequence) showing a 2.1 cm heterogeneously enhancing mixed solid/cystic mass in between the deep and superficial lobes of the left parotid (arrow).

Figure 4

(A) H&E section of an area of the lesion, lined by keratinising stratified squamous epithelium and filled with laminated keratin. In addition, there was very little associated inflammation in this area. In (B–D) are Ki67, p53 and p63 immunohistochemical stains respectively. The Ki67 index is low and located at the basal layer of the cyst lining. Both p53 and p63 are not overexpressed and have a similar distribution to Ki67.