All three specimens appeared similar upon histological examination (fig 2). Each lesion appeared well circumscribed and was composed of nests and trabeculae of uniform, polygonal cells with abundant, finely granular eosinophilic cytoplasm.
Figure 2Tumour composed of bland cells with abundant granular, eosinophilic cytoplasm (haematoxylin and eosin, original magnification ×200).
The caruncle is a unique anatomical structure containing elements of both conjunctiva and skin.5
Oncocytomas (oxyphilic adenomas) of the caruncle are rare tumours accounting for only 3–8% of masses of the caruncle.6
These cases are unusual in that, to our knowledge, this is the first series in which three cases presented in the space of eight weeks. This begs the question: are we misdiagnosing or indeed underdiagnosing these tumours, because not all are sent for pathology and how important or relevant is this?
Oncocytomas are benign neoplasms of oncocytic cells, which can occur at a variety of sites. Ocular adnexal oncocytomas are usually situated in the lacrimal drainage apparatus of the caruncle.7
Cases occurring in other sites such as the eyelid8
have also been documented. The differential diagnosis should include melanocytic melanoma at the top of the list; as this carries the worst prognosis, melanocytic naevus, benign epithelial tumours, pyogenic granulomas and haemangiomas, along with several other rarer lesions.9
As already mentioned, oncocytomas are by and large benign in nature and usually only require excision for cosmetic purposes or if they cause irritation to the patient. They do, however, have a real potential to recur in cases of incomplete excision10
and can be locally aggressive and occasionally turn malignant.