Unusual Carcinomas of the Lacrimal Gland: Epithelial-Myoepithelial Carcinoma and Myoepithelial Carcinoma

Of all intrinsic lacrimal gland masses, 28% are epithelial neoplasms.¹Epithelial-myoepithelial carcinoma (EMC) and myoepithelial carcinoma (MC) are uncommon epithelial malignancies of the salivary gland that have been rarely reported in the lacrimal gland.²Herein, we report 2 patients with each of these tumors in the lacrimal gland and compare and contrast these unusual neoplasms.

An 86-year-old man presented with painless double vision for 6 months. His visual acuity was 20/30 OD and 20/50 OS. He had a palpable mass under the left superolateral orbital rim and bilateral symmetrically decreased tear function. His palpebral fissure was 9 mm OD and margin reflex distance, 5 mm OD, compared with 6 mm and 3 mm, respectively, OS. Exophthalmometry was 13 mm OD and 16 mm OS. He had limited elevation, abduction, and adduction of the left eye with an 8-diopter left hypotropia. Computed tomographic scan of the orbits showed a 2.5 × 1.8-cm, moderately homogenous, hyperattenuating structure in the region of the left lacrimal gland with an area of scalloping in the lacrimal fossa (Figure 1A). The appearance was suspicious for transformation of a pleomorphic adenoma to malignancy. The patient underwent a lateral orbitotomy for resection of the lacrimal mass that was found to be adherent to the periosteum with irregularity of adjacent bone. Because of this, the underlying bone of the lacrimal fossa was sent for histopathological examination. The gland revealed a biphasic tumor containing the typical bilayered pattern of EMC (Figure 1B and Figure 2A, C, and E), with areas of myoepithelial anaplasia (Figure 1C). The latter occupied approximately half of the tumor volume and was composed of a solid component of cells with myoepithelial features and prominent atypia, including nuclear pleomorphism, enlarged nucleoli, mitotic figures, and focal necrosis (Figure 1D). Extension to the anterior, superior, and inferior resection margins was present. The bone specimen was negative for invasion; therefore, the tumor was classified as T2N0M0. Surgical treatment was followed by adjuvant radiotherapy of 6000 cGy because of positive margins. Repeat computed tomographic scan at 8 months postoperatively showed no evidence of recurrence. The patient died 15 months after excision, with no clinical evidence of recurrent disease.

An 84-year-old man presented with severe left ocular pain and visual loss for 2 weeks. His visual acuity was 20/30 OD and hand motions OS. A full-diameter corneal ulcer with impending perforation was present in the left eye, which was proptotic by 10 mm and displaced inferonasally. Computed tomographic scan demonstrated a 3.2 × 2.6 × 2.2-cm, well-circumscribed, calcified lacrimal gland mass extending to the apex, displacing the globe inferiorly and medially with irregularity in the adjacent bony orbital wall (Figure 3A). Incisional biopsy of the lacrimal gland revealed MC. Metastatic workup findings were negative so left eyelid-sparing exenteration was performed along with excision of the adjacent bone. Histopathological examination revealed MC arising in a pleomorphic adenoma (Figure 2B, D, and F and Figure 3B), with a predominant epithelioid pattern (Figure 3C) and focal clear cell areas (Figure 3D). There was a moderate degree of cytologic pleomorphism and atypia with vesicular nuclei, prominent nucleoli, and necrosis in a comedolike pattern (Figure 2F). The mitotic rate was 3 per 10 high-power fields. The bone was invaded by carcinoma, leading to a classification of T4bN0M0. The patient refused follow-up and further treatment.

Epithelial-myoepithelial carcinoma is a rare neoplasm accounting for approximately 1% of all salivary gland neoplasms, with most cases arising in the parotid gland.³Only 2 cases of primary EMC of the lacrimal gland have been reported.²Classically, this neoplasm shows a biphasic pattern of a central inner layer of cuboidal ductal epithelial cells surrounded by a peripheral outer layer of myoepithelial cells, often with clear cytoplasm. In the largest series, reported by Seethala et al,³there was a biphasic pattern in some areas in all tumors. The mean epithelial to myoepithelial ratio was 0.56 but ranged from 0.05 to 2.33. Epithelial-myoepithelial carcinoma of the salivary gland is considered to be a low-grade malignancy, with a recurrence rate of 36.3% and a survival rate of 93.5% and 81.8% at 5 and 10 years in the series of Seethala et al.³Factors significantly affecting disease-free survival were positive margins, lymphovascular invasion, necrosis, and myoepithelial anaplasia. Three of 45 patients died of disease, 2 with local recurrences and 1 of distant metastasis. Our patient had 3 of 4 poor prognostic factors, including positive margins, necrosis, and myoepithelial anaplasia.

Myoepithelial carcinoma has also been reported rarely in the lacrimal gland in large series, but not illustrated. It also occurs most commonly in the parotid gland and is defined as a malignant neoplasm with histologic evidence exclusively of myoepithelial differentiation.⁴It does not show tubule formation or the biphasic pattern characteristic of EMC. The largest series of 25 patients with salivary gland MC, reported by Savera et al,⁴had 10 high-grade and 15 low-grade lesions. Fifteen tumors arose in the background of a preexistent benign lesion, 2 benign myoepitheliomas and the remainder pleomorphic adenomas. This neoplasm is characterized by all of the different histologic patterns that myoepithelial cells assume: epithelioid, clear, hyaline (plasmacytoid), spindle, and mixed, with most neoplasms having 2 or more patterns. Ten of 17 had recurrences and 8 had metastases. Five patients (29%) died of disease after a mean of 32 months, 2 were alive with metastases, and 10 were alive or died without disease after a mean of 42 months. No histologic factors correlated with outcome statistically. Thus, the prognosis for MC is generally worse than that for EMC.

Most rare epithelial neoplasms of the salivary glands have now been reported in the lacrimal gland. Consequently, it is important for the ophthalmic pathologist to be cognizant of this and familiar with the most recent World Health Organization classification of salivary gland neoplasms when diagnosing an unusual lacrimal tumor.⁵It is important to study the entire tumor pathologically. Further investigation will be required to determine if recognition of the same entities is as important for prognostication in the lacrimal gland as in the salivary gland. It is also imperative that any bone removed be examined pathologically for proper staging, as demonstrated by our 2 cases.

Correspondence:Dr White, Department of Pathology and Laboratory Medicine, Vancouver General Hospital, 910 W 10th Ave, Vancouver, BC V5Z 4E3, Canada (val.white@vch.ca).

Financial Disclosure:None reported.