Most lacrimal gland lesions are inflammatory or lymphoid neoplasms.1 Nonlymphoid neoplasms are less common, and most areprimarily epithelial in origin.1,2 Amongthem, pleomorphic adenoma and adenoid cystic carcinoma are the most commonbenign and primary malignant tumors, respectively, accounting for 12% and4% of all lacrimal gland lesions.2 Epithelial-myoepithelialcarcinoma is an exceptional malignant epithelial tumor in view of its rarityand the relative lack of understanding of its clinical behavior. These raretumors usually occur in the salivary gland, and, to our knowledge, only 2cases in the lacrimal gland have been reported. One of these was a hybridcarcinoma and the other was an epithelial-myoepithelial carcinoma with pleomorphicadenoma background.1- 5 Weherein report a case of de novo epithelial-myoepithelial carcinoma of thelacrimal gland.
An 80-year-old Chinese man had a painless, palpable subcutaneous massin his left upper outer eyelid for 9 months. On examination, a contrast-enhancingmass of 1 cm in diameter was confirmed to arise from the left lacrimal gland,as demonstrated on the computed tomographic scan. The left eye was the patient’sonly functioning eye, with a visual acuity of 20/50; his right eye had beenlost to trauma 15 years earlier. He was treated conservatively, as he refusedany intervention for diagnosis. The mass gradually enlarged and displacedthe left eye nasally and inferiorly. Adduction was reduced. There was alsosignificant chemosis involving the upper bulbar conjunctiva. No lymph nodescould be palpated over the cervical and supraclavicular regions. Systemicreviews, including abdominal, respiratory, cardiovascular, and neurologicexaminations, were unremarkable. The complete blood cell count, inflammatorymarkers (including erythrocyte sedimentation rate and C-reactive protein level),and biochemical profiles were all normal. A chest radiograph was clear, andresults of an ultrasonographic examination of the abdomen were normal. Repeatedcomputed tomographic scan (Figure 1)of the orbit 10 months after the first examination showed a mildly enhancedsoft-tissue mass arising from the left lacrimal gland and pushing the globeposteriorly with bulking of the optic nerve. It measured 24 × 15 × 18mm. No intraocular invasion or bony erosion could be seen.
Computed tomographic scan of theorbit showing a mildly enhanced lacrimal soft-tissue mass arising from thesuperolateral aspect of the left orbit.
The patient eventually agreed to an excisional biopsy, and it was performedvia a standard translid lateral orbitotomy. The tumor was a well-encapsulatedmass and was removed en bloc uneventfully. There was no postoperative complication,and visual acuity returned to 20/50. Histopathological examination disclosedepithelial-myoepithelial carcinoma of the lacrimal gland. Foci of capsularinvasion and tumor nests at the surgical margin were present. Exenterationor external beam radiotherapy was offered to the patient but was declined,as this was his only seeing eye. He was kept under close observation. Twoyears after surgery, there was no evidence of local recurrence or metastasis.
Gross examination showed a firm, well-circumscribed mass measuring 2.3 × 1.8 × 1.8cm composed of homogeneously tan fleshy tissue without hemorrhage, necrosis,or calcification. Microscopic sections showed a fibrous encapsulated cellulartumor (Figure 2) with multiple fociof capsular invasion (Figure 3). Thetumor was heterogeneous. In some areas, the tumor was in the form of glandsthat were lined by 2 cell types, the inner epithelial and the outer myoepithelialcells. Similar to a normal functional lacrimal acini unit, with an epitheliallining surrounded by myoepithelial cells, the immunohistochemical stainingpattern of this tumor was reminiscent of such a pattern. The inner cuboidalcells did not show immunoreactivity for myoepithelial markers such as S100protein and smooth-muscle antigen (Figure 4 and Figure 5) but exhibited positivity with cytokeratin(clone AE1/AE3) and epithelial membrane antigen. In contrast, the outer layerof cuboidal or flattened cells was positive for S100 protein and SMA immunostain(Figure 4 and Figure 5), confirming that they were myoepithelial. In other areas,the tumor was in the form of oval and spindled cells forming nests and sheets.We noted moderate cellular pleomorphism and 5 mitoses in 40 high-power fields(Figure 6). The nuclear pleomorphism,frequent mitoses, and capsular invasion were features of a malignant tumor.Extracellular globules of hyaline material were focally present. Focal clearcell change was seen. These oval and spindled cells were also positive forthe myoepithelial immunomarkers, indicating that they were derived from overgrowthof the myoepithelial component (Figure 7 and Figure 8). Above all, these immunohistopathologicalfeatures were diagnostic of epithelial-myoepithelial carcinoma. No perineuralor perivascular invasion could be seen. There was no other preexisting abnormalityassociated with this tumor, suggesting it was a de novo, isolated tumor. Thecharacteristic biphasic cell arrangement and immunostaining features helpedto distinguish this tumor from common differential diagnoses such as adenoidcystic carcinoma with an infiltrative cribriform growth pattern and pleomorphicadenoma with melting of the epithelial cells in myxoid or chondroid stroma.6,7
Low-power photomicrograph showinga well-circumscribed encapsulated tumor (hematoxylin-eosin, original magnification×2).
Area of capsular invasion (hematoxylin-eosin,original magnification ×10).
Staining of inner and outer layersof cells for S100 protein. The inner-layer cells are S100 negative, whereasthe outer-layer cells are S100 positive (original magnification ×20).
Staining of inner and outer layersof cells for smooth-muscle antigen. The inner-layer cells are negative forsmooth-muscle antigen, whereas the outer-layer cells are smooth-muscle antigenpositive (original magnification ×20).
Nuclear pleomorphism and frequentmitoses, indicating malignancy (hematoxylin-eosin, original magnification×20).
Staining of spindle-cell areas forS100 protein. The positive staining indicates that the spindle-cell areaswere derived from overgrowth of the myoepithelial component (original magnification×20).
Staining of spindle-cell areas forsmooth-muscle antigen. The positive staining confirms their myoepithelialdifferentiation (original magnification ×20).
Epithelial-myoepithelial carcinoma is a rare malignant tumor that ismore commonly encountered in salivary glands and comprises 1% of all salivarygland tumors.8- 10 Itsoccurrence in the orbit is extremely rare.2 Myoepitheliomacan be subclassified histologically into different morphologic types suchas chondromyxoid, spindle, hyaline, and epithelial, including the clear-cellvariants.2 The epithelial type is believedto behave in a more malignant fashion than the former 2 groups. In the Englishliterature, we found only 1 case of hybrid carcinoma occurring as a mixedtumor, and 1 associated with a preexisting pleomorphic adenoma in a 63-year-oldman with an 8-year history of painless proptosis.2 Toour knowledge, this is the first reported case of de novo epithelial-myoepithelialcarcinoma of the lacrimal gland without any other tumor background. This malignanttumor, though rare, should be included in the differential diagnosis of lacrimalgland tumor.
Malignant tumor may mimic a benign lesion by deceptively appearing asa painless and slowly growing mass.2,11 Inour case, sudden disproportionate rapid growth suggested its malignant nature,and repeated radiologic imaging was implemented accordingly. Theoretically,computed tomographic scanning with contrast could help to discriminate epithelialfrom lymphoid or inflammatory lesions of the lacrimal gland.12 However,the reliability of this modality in differentiating a malignant from a benignepithelial lesion is known to be poor.2 Radiologicfeatures such as hyperostosis and tumor calcification, which were generallyconsidered to be features of malignancy, might not be apparent in all cases,as in our patient.12 Pathological diagnosisby open biopsy is therefore the last resort in confirming underlying disease.5
Recurrence and metastasis rates of epithelial-myoepithelial carcinomafrom salivary gland have been reported to be from 35% to 50% and from 8.1%to 25%, respectively.8 In this case, the presenceof tumor at the surgical margin suggests that radiotherapy or orbital exenterationmay be necessary.2 However, the ophthalmiccomplications or morbidity of the treatment should be discussed with the patient,especially in considering the patient’s expectations, older age at initialexamination, and, in our patient, the sole functional eye. Our patient acceptedthe limited procedure of tumor excision only. During 24 months of follow-up,there was no evidence of either local recurrence or metastasis, and usefulvision was successfully preserved. This rare tumor may behave as a low-grademalignant neoplasm, in contrast to other epithelial malignant tumors of thelacrimal gland, such as adenoid cystic carcinoma, which usually has a muchpoorer prognosis.2- 5 However,lifelong follow-up is required, as recurrence or metastasis may occur yearsafter surgery.
Correspondence: Dr W.-M. Chan, Departmentof Ophthalmology and Visual Sciences, Chinese University of Hong Kong, HongKong Eye Hospital, 147K Argyle St, Kowloon, Hong Kong (email@example.com).
Financial Disclosure: None.
Wai-Man Chan, David T. L. Liu, Lawrence Y. M. Lam, Paul C. L. Choi, Carmen K. M. Chan, Dennis S. C. Lam, Nongnart R. Chan. Primary Epithelial-Myoepithelial Carcinoma of the Lacrimal Gland. Arch Ophthalmol. 2004;122(11):1714–1717. doi:10.1001/archopht.122.11.1714