Mucoepidermoid carcinoma predominantly originates from salivary glands. Ocular tissues affected with this neoplasm include conjunctiva, lacrimal sac, and lacrimal gland. The aggressive nature of the tumor and its tendency for intraocular invasion are well-known. Though distant metastasis to preauricular/cervical lymph nodes and liver has been reported, the incidence is quite low. However, there have been no reports of mucoepidermoid carcinoma metastatic to the lung. Hereby, we report a case of a 36-year-old lady with mucoepidermoid carcinoma of the conjunctiva (MECC) presenting with intraocular invasion, orbital extension and metastasis to the lung.
A 36-year-old lady presented with redness and decreased vision in right eye for 6 months. She was earlier diagnosed of a cavitary lung lesion, presumed secondary to tuberculosis and treated with anti-tubercular treatment for 4 months. At presentation, vision was nil light perception in the affected right eye. The left eye was essentially normal. Examination revealed conjunctival congestion with a diffuse vascularized conjunctival mass in the inferotemporal bulbar conjunctiva and proptosis [Fig. 1a]. Iris neovascularization, 360° closed angles with intraocular pressure of 48 mm Hg, and a choroidal mass with total retinal detachment were noted. Ultrasound of right eye revealed diffuse choroidal thickening with uveal mass, widening of the tenon's space and diffuse orbital tumor [Fig. 1b]. Magnetic resonance imaging scan revealed uveal mass and diffuse orbital tumor [Fig. 1c]. A diagnostic needle biopsy of the uveal mass revealed the presence of atypical cells in necrotic background suggestive of malignancy. The patient underwent lid-sparing exenteration of the right eye [Fig. 1d]. Histopathological examination of the exenterated specimen revealed the presence of mucoepidermoid carcinoma with multiple tumor emboli within the blood vessels of the orbital tissue [Fig. 1e and f]. Extensive invasion into the orbital tissue, muscle fibers, sclera, choroid and optic nerve was noted. Postoperative period was uneventful. Before orbital exenteration, she also underwent computed tomography-guided biopsy of the cavitary lesion in the left lung that revealed squamous cell carcinoma (SCC) [Fig. 2a and b]. In view of the systemic spread, radiotherapy was advised. At 3 months follow-up, two cycles of radiotherapy were completed, and the right socket was healthy.
Mucoepidermoid carcinoma of the conjunctiva often presents as a limbal or bulbar conjunctival mass with symptoms of chronic irritation. It was reported for the first time in conjunctiva by Rao and Font in a series of five cases in 1976, all the five cases had recurrence within 6 months. Clinical morphology can range from simple conjunctival nodule to leukoplakic, infiltrative, ulcerative, and papillomatous lesions. Histopathology of MECC is variable. Our case revealed tumor cells arranged in lobules with fine septa separating them. The cells had squamoid morphology with duct-like structures and were seen infiltrating sclera and orbital tissue. Tumor emboli were seen in blood vessels. The tissue was positive for alcian blue staining [fig. 3].
Review of literature suggests the role of intraocular invasion by tumor cells to be implicated in the mucinous differentiation in the tumor, and perhaps mucinous metaplasia is due to intraocular factors. Lymph node involvement has been described, but distant metastasis is unusual if the tumor is treated aggressively. Seitz and Henke. suggested that early enucleation including normal appearing tissue next to the globe should be considered for treatment of primary mucoepidermoid carcinoma to avoid later exenteration or metastasis. Johnson et al. and associates reported two cases of MECC presenting with cervical lymph node metastases, in a series of 30 invasive secondary orbital SCC that were treated with exenteration and radical neck dissection. Recurrence is also a common feature of MCC occurring to the extent of 79%, most commonly in the first 6 months of follow-up.
In our patient, extensive orbital disease at the time of diagnosis necessitated exenteration and vascular invasion was seen histopathologically. There was a large cavitary lesion in the left upper lobe of lung with central necrotic area and nodular enhancing soft tissue toward the hilum with a fairly thin, uniform wall. Systemic metastasis was treated with radiation therapy. The patient was recovering well. Given the high frequency of misdiagnosis and incorrect management, it is essential that proper histopathological examination be carried out. The treatment strategy is decided once the status of intraocular spread as well as distant metastasis is known.
Mucoepidermoid carcinoma of the conjunctiva is rare, aggressive variant of SCC, characterized histopathologically by both mucoid and epidermoid cells, which requires urgent intervention to prevent metastasis. Increased awareness of subtle clinical and pathologic findings and rigorous sequential treatment strategies should help clinicians and surgeons in the treatment of MECC for improved outcomes and better prognosis.
Dr. Jyotirmay Biswas, MD for help with histopathologic slides.
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Conflict of Interest: None declared.