A Rare Case of Myoepithelioma around the Left Orbit

Atypical presentation of invasive myoepithelioma in a pediatric patient

A 15-year-old girl presented with a mobile lesion with yellowish hue on the posterior lamella of the right lower eyelid adjacent to the punctum. Four years prior, a lesion thought to be a chalazion was excised from the same location. There was subsequent progressive painless enlargement. The patient ultimately underwent an internal excision of the mass. Histopathology demonstrated infiltrative nests and cords of epithelioid and plasmacytoid cells with abundant eosinophilic myxoid-collagenous stroma along with focal infiltration of skeletal muscle with immunohistochemical staining consistent with an invasive myoepithelioma of mixed-cell type. Given concern for invasive disease, the patient underwent subsequent Mohs resection resulting in a 25% full thickness eyelid defect, which was repaired with direct closure of the wedge defect. There has been no recurrence of the disease for 7 months since the Mohs resection. This case illustrates the atypical presentation of an invasive myoepithelioma of the eyelid in a pediatric patient.

Primary Myoepithelial Carcinoma of the Conjunctiva

A 38-year-old female, otherwise fit and well, presented with a mass on her left medial bulbar conjunctiva that had been enlarging for several months. Examinations showed a fixed pinkish tumour, 9 mm in maximum extent, spanning from the plica to the medial limbus. The tumour was removed in toto. Histology revealed it to be a biphasic tumour composed of lobules and infiltrative cords within a sclerotic matrix. The cells were spindle-shaped to epithelioid, with nuclear atypia and occasional mitotic figures. The tumour was positive for smooth muscle actin, beta-catenin, and vimentin. All other markers of myoepithelial differentiation and cytokeratins were negative. Genetic analysis showed no evidence of EWSR1 or PLAG1 rearrangements. The light microscopic features and immunohistochemistry strongly supported a tumour with myoepithelial differentiation. The cellular atypia, mitotic activity, and infiltrative edges all pointed to myoepithelial carcinoma. Body imaging/screening showed no evidence of tumour elsewhere, supporting that the tumour was a primary of the conjunctiva. This is the first report of a myoepithelial tumour of the conjunctiva. The patient remains recurrence-free after 3 years of follow-up.