Canaliculops: clinical examination

Canaliculops (or canaliculocele) is an ectasia of the canalicular wall, mostly idiopathic in origin. However, the role of trauma and inflammation as the initial insult to canalicular system has been suggested by some authors. Being a rare condition, most ophthalmologists are unfamiliar with the condition with consequent high likelihood of misdiagnosis or sometimes overdiagnosis.

A 42-year-old male patient presented to the outdoor department with a painless swelling in the right lower lid, which had been present for the previous 2 months (Fig. 1). There was no itching, watering, or discharge. Three months earlier, the patient had experienced pain and redness in the region devoid of any discharge. It was documented as lower lid canaliculitis by an ophthalmologist and had resolved completely over a few days on conservative treatment with topical antibiotics and oral analgesics. At presentation, best-corrected visual acuity in both eyes was 6/6 with glasses. On examination, the swelling was measured about 10 mm, round, pea-sized, fluctuant, and bulging more toward the conjunctival side. The overlying skin appeared normal. However, the conjunctival side had a white-opaque surface with faint bluish hue (Fig. 2). The punctum seemed to be involved by the swelling, yet no stenosis was present. There was no redness, tenderness, discharge, or epiphora. No regurgitation of fluid (water/mucus/pus) was noted from the punctum on pressing the swelling. Fluorescein dye disappearance test result was normal and comparable with the fellow eye. On syringing through the lower punctum, free flow of fluid in throat was felt, with absence of regurgitation, establishing the patency of the lacrimal drainage system. No change in the size of the swelling was noted before, during, or after irrigation. We performed a transillumination test in a dark room, which was positive with brilliant transillumination confirming the clear, cystic nature of the lesion (Fig. 3). Marsupialization of the cyst was done through the conjunctival side. The medial cut end of the canaliculus was clearly visible in the wound, which implied that the cyst was of canalicular origin. A specimen of the cyst wall was sent for histopathology, which revealed normal canalicular epithelium (i.e., nonkeratinized, stratified squamous epithelium; no goblet cell) without any inflammatory infiltrate. Hence, a diagnosis of left lower lid canaliculops was made. No epiphora or recurrence was seen during follow-up.

On the basis of history and appearance, our case fits the classical presentation of canaliculops as described in the literature. Negative history of discharge or canaliculoliths rules out the possibility of infectious canaliculitis in this case. Hence, the possibility of idiopathic origin here is more likely.

The hypothesis of “ball-valve mechanism” caused by redundancy of hyperplastic epithelium of canaliculus and “congenital weakness” of a diffuse segment of canalicular wall reflects the underlying functional problem. Yet, surprisingly, the lacrimal system remains patent both anatomically and functionally, as demonstrated in this case by syringing and dye disappearance test, respectively. Similarly, patency of punctum is not an unusual finding, even though rare instances of punctal stenosis or aplasia have been mentioned in the literature.^, 

Expression of discharge with gentle pressure on the swelling is a critical indicator of the 2 close differentials of cannaliculops, namely, canaliculitis or diverticulum of canaliculus. The absence of this sign in our case easily excludes these 2 possibilities.

Our aim is to emphasize simple clinical tests to identify this condition in any patient presenting with medial eyelid swelling. Positive fluctuation test could recognize the cystic nature of the lesion but could not differentiate its content. Positive external transillumination test was the only indirect clinical test to distinguis the clear content in the cystic lesion. External transillumination is a noninvasive test, which has a decisive role in certain ophthalmologic as well as nonophthalmologic conditions.^,  Although the technique varies according to the location of the lesion, a dark room and a good illuminator are prerequisite to perform this test.^,  We strongly believe that the relatively thin lid and absence of tarsus medial to the punctum increases the reliability of this test in canaliculops.

To conclude, precise history and meticulous clinical examination is indispensable in identifying this rare entity. Histopathology is a prerequisite in all cases to avoid misdiagnosis.