A grey keratinous tarsal cyst with Gram+ cocci.

Abstract

A 51-year-old Caucasian woman had noticed a slowly growing lump in her left upper eyelid for 6–12 months. She had had breast cancer resected 4 years earlier. Because of positive sentinel lymph nodes, she also had received adjuvant chemotherapy and radiotherapy, and she was on anti-oestrogen therapy. No previous eyelid surgeries had been performed. She had had cosmetic tattooing done to her eyelids 20 years earlier. Upon eversion of her left upper eyelid, a grey subconjunctival tumour of 2 mm diameter was visible in her tarsus (Fig. 1A). Its anterior surface could be felt through the skin. The anterior lamella of the eyelid moved freely over the tumour. Her visual acuity was 20/20. Because of the dark grey colour of the tumour, conjunctival melanoma was considered as one possibility. The tumour was removed with surrounding tarsus using a no-touch technique and a 1.5 mm wide margin. It extended through the tarsus to its anterior surface but did not invade more superficial eyelid tissues. Histopathologic examination reve-aled a cyst filled with keratin and lined by stratified squamous epithelium (Fig. 1B). The cyst was located in the centre of the tarsal plate, bulging the conjunctiva. Lobules of Meibomian glands and accessory lacrimal glands were seen near it. No inflammatory cells, goblet cells, keratohyalin granules or sebaceous elements were present in the cyst wall. Gram stain revealed abundant Gram+ cocci within the cyst (Fig. 1C). Immunostaining for carcinoembryonic antigen (CEA; Fig.1D) and epithelial membrane antigen (EMA) showed immunoreaction in the cuticular layer and in the contained keratin. Prussian blue stain for iron and Fontana–Masson stain for melanin were negative. The most common benign tarsal tumours in Caucasians are chalazia and conjunctival concretions (Kulshrestha & Thaller 1995). Benign, non-inflammatory tarsal cysts in six patients were recently documented to be of Meibomian gland origin (Jakobiec et al. 2010). They were designated intratarsal keratinous cysts. Twenty-one additional patients have been reported later including one patient with multiple cysts and one with spontaneous extrusion of cyst contents (Patel et al. 2011; Kim et al. 2012; Rajaii et al. 2013; Zhang et al. 2013). Some lesions originally reported as epidermal inclusion cysts, epidermoid cysts and steatocystoma simplex were recently also considered to be consistent with the diagnosis of an intratarsal keratinous cyst of Meibomian gland origin (Jakobiec et al. 2010; Patel et al. 2011), which possibly is the third most common but currently underdiagnosed benign tarsal tumour. Intratarsal keratinous cysts of Meibomian origin attach tightly to the tarsus and often protrude on its conjunctival side. They reportedly recur unless completely excised (Jakobiec et al. 2010). Their histopathological findings are straightforward, and the immunostaining pattern helps to differentiate them from common epidermal and steatocystoma cysts. These cysts are usually white to yellow in colour. Two of the six cases in the original series were bluish, however, and one was grey just as in our patient (Jakobiec et al. 2010). The bluish colour was ascribed to Tyndall's effect – that is, certain suspensions reflect short wavelength light – but the origin of the grey colour was not addressed. Both in our patient and in the previously reported grey cyst, abundant Gram+ cocci were present (Jakobiec et al. 2010). We are unaware of other intratarsal keratinous cysts with bacteria. Therefore, we propose that the occasional grey colour of these cysts, which can raise the suspicion of conjunctival melanoma, is either directly or indirectly associated with presence of bacteria, in both cases Gram+ cocci, within the cyst. Knowledge of this possibility helps to avoid misdiagnosis and excessively wide resection of this benign lesion. Various other lesions may mimic tarsal conjunctival melanoma as well, such as retained foreign bodies, argyrosis and epinephrine deposits (Shields & Shields 2008). In our experience, conjunctival melanomas occurring in the tarsal conjunctiva tend to be associated with adjacent primary acquired melanosis and be vascularized, further differentiating them from keratinous cysts that are circumscribed and not vascularized.