Epithelial-myoepithelial carcinoma of lacrimal gland from an ex pleomorphic adenoma

Abstract

A 47-year-old man with a history of recurrent pleomorphic adenoma of the right lacrimal gland presented with rapid onset of a swelling in the right orbit. Initial imaging with CT showed that the swelling was grossly involving the extraocular muscles. Hence we had a suspicion of malignant transformation, so a radical approach in the form of right orbital exenteration with anterior skull base resection and temporalis muscle reconstruction was taken. Postoperative histology revealed epithelial-myoepithelial carcinoma, with immunopositivity for epithelial and myoepithelial components. Adjuvant radiation of 60 Gy was given with three-dimensional CT-based planning. This case portrays the importance of adjuvant treatment in recurrent pleomorphic adenoma and chance of malignant transformation in rare histologies.

Figure 1

Contrast-enhanced CT of face and neck revealing well-circumscribed heterogeneously enhancing mass in the right lacrimal fossa with displacement of globe inferiorly. Mass was causing expansion of orbit with destruction and remodelling of lateral wall of right orbit involving medial, superior rectus and all oblique muscles.

Figure 2

(A and B) Gross specimen of globe with a 3×3 cm tumour grossly involving extraocular muscles.

Figure 3

(A) Photomicrograph showing a tumour with infiltrating borders and tumour cells arranged in sheets (×10). (B) Tumour is composed of bilayered tubules (×20). (C) Tubular structures are lined by ductal cells and surrounded by an outer layer of clear cells (myoepithelial cells) (×40) (all H&E stain).

Figure 4

(A–C) Immunopositivity for epithelial membrane antigen, smooth muscle antigen and S-100, respectively.

Figure 5

(A) Clinical target volume (CTV) included entire preoperative tumour volume with 5 mm margin. Planning target volume (PTV) was generated with 5 mm margin to CTV. (B and C) Dose colour wash and dose volume histogram of 95% of PTV receiving 57.11 Gy.