Editor, We present the clinical and histologic findings in a series of four cases of dacryolithiasis in the lateral fornix. All four patients (one female, three male patients aged 21, 43, 51 and 66, respectively) were examined by slit lamp microscopy, and ultrasonography was performed in three. One patient underwent magnetic resonance imaging (MRI) (Fig. 1). The excised tissue and concretions were fixed in paraformaldehyde and embedded in paraffin. Ophthalmopathologic examination of paraffin sections included routine staining with hematoxylin and eosin and Periodic acid-Schiff as well as special stains for microorganisms. All provisions followed the Tenets of the Declaration of Helsinki. Patients gave written consent for study inclusion. (A) T1-weighted Magnetic resonance imaging. Arrows mark dacryolith; (B) Yellowish mass at the lateral canthal angle; inset shows removed dacryoliths; (C) cilium (arrow) with chronic inflammatory cells, giant cell (short arrow), dacryoliths (asterisks), magnification bar: 100 μm (hematoxylin-eosin). The clinical presentation of dacryoliths of the temporal canthus varies between a tumorous aspect and a non-specific inflammatory swelling. Thus, pre-operative diagnosis is difficult. All patients presented with a short duration of symptoms with little pain unresponsive to conservative treatment. Lesions were located in the region of the outlet duct of the lacrimal gland at the lateral canthus and appeared slightly hyperemic. Macroscopic characteristics of stones varied between small multiple round whitish–yellow concretions of hard consistency (0.7 mm in diameter, in association with a large dacryops) and bigger more irregular stones (up to 7 mm, in patients without surrounding cystoid structure). In all specimens, the histopathologic examination revealed amorphous acellular organic material without any evidence of microorganisms. In one patient, sections showed a cilium surrounded by an infiltrate of chronic inflammatory cells. The pathogenesis of stone formation in the ductules of the lacrimal gland is uncertain. Twelve cases of dacryoliths in the lacrimal gland have been reported (Naito et al. 1973; Duke-Elder 1952; Baker & Bartley 1990; Baratz et al. 1991; Mawn et al. 1997; Zafar et al. 2004; Halborg et al. 2009). In our series of four patients, there was no evidence of Actinomyces, Haemophilus influenzae or any other microorganisms in the sections examined. In one of our patients, histopathology showed a cilium closely associated with the dacryolith. Regarding the small number of cases a causative relation can hardly be proven. However, the findings suggest that cilia, amongst other potential agents, can possibly cause dacryolith formation in the lacrimal gland. It may be assumed that the relatively shorter ductal system and the few organic components in tears prior to their exposure to lipids, cell debris and bacteria on the ocular surface are responsible for their rare incidence and their mostly ‘sterile’ nature. However, microorganisms as the inciting but eventually no longer detectable agent cannot be excluded. The short duration of symptoms, on the other hand, would argue against such a mechanism. Bacteria associated with dacryolithiasis in the lacrimal gland may be more likely to be a secondary phenomenon since short history cases do not show any evidence of bacteria (this study), while microorganisms could primarily be detected in patients with a longer history of symptoms (Halborg et al. 2009). Both ultrasonography and MRI appear ineffective in reliably identifiying dacryoliths in the lacrimal gland ductule. Surgical intervention leads to rapid relief of symptoms and regression of clinical signs. Despite their infrequent occurrence lacrimal gland ductular dacryoliths should be included in the differential diagnosis of patients with a symptomatic or asymptomatic tumour in the lateral fornix or a chronic unilateral conjunctivitis.