Case Report

An otherwise healthy 78-year- old Caucasian female with a history of oral lichen planus presented to RRW on 8/18/08 (Figure 1) with a one-year history of continual bilateral tearing, greater on the right. There was no pain or foreign body sensation. She was sensitive to lacrimal probing, which demonstrated anatomically patent lacrimal drainage systems but with copious reflux from the non-cannulated punctum bilaterally justifying a diagnosis of functional nasolacrimal system obstruction. Bilateral Dacryocystorhinostomies (DCR) were performed on 8/19/09. The surgical procedures were initially successful through five months post-operatively during which she was tearing free. However, by eight months post DCR the tearing had recurred bilaterally. In addition, a conjunctival inflammatory process was obvious on eversion of her right lower eyelid (Figure 2). Non-response to topical lubrication steroids and antibiotics prompted an initial incision and drainage for presumed pyogenic granuloma or chalazion without pathology. The inflammatory process slowly recurred including a purulent appearing microcyst (Figure 3) leading to a conjunctival biopsy sent to Eye Pathology at UCI 11/18/2010, one-year following the DCR. Clinical photos before the first excision revealed a purulent micro-cyst, correlating with the histology demonstrating a pyogenic granuloma (Figure 2-4). Pathologic study revealed incompletely excised micro-nodules of acutely and chronically inflamed granulation tissue partially covered by conjunctiva with focal pseudoepitheliomatous hyperplasia, necrosis and crush artifact. Step-sections of the deeper portions of the first specimen revealed non-polarizing membranous debris, suggestive of chitin of insect or parasite origin, within a well-defined fibrous envelope (Figure 5). In-spite of treatment by multiple other ophthalmologists, topical steroids, antibiotics, and twelve serial 0.02% mitomycin-C topical applications over six months recommended by consultants who suspected conjunctival lichen planus, the lesion persisted leading to a second deeper excisional biopsy three months later revealing only granulation tissue. After this second biopsy the area eventually healed with no recurrence.

 

Figure 1: Initial clinical appearance of right lower eyelid inflammation 8/18/2008.

 

Figure 2: Appearance of everted right lower eyelid 8-months after DCR demonstrating inflammation and scarring residual to incision and drainage prior to biopsy with pathology.

 

 Figure 3: Subsequent appearance several days after Fig. 2 including a small cyst containing purulent material.

 

Figure 4: Photomicrograph of H&E-stained section after first biopsy with pathology, received 11/18/2010 illustrating partially necrotic abscess-like inflammatory reaction consistent with clinical appearance in Fig. 3. Black ink placed at gross exam delineates margin of excision. (Original magnification X 200)

 

Figure 5: Photomicrograph of H&E-stained deeper step-section of same tissue block as in Fig. 4, revealing a cystic epithelial inclusion with intraluminal remnants of the parasite, and a background of capillary proliferation and a mixed inflammatory infiltrate typical of pyogenic granuloma (original magnification X 200)

Methods

We reviewed all clinical and pathology records related to this case. She had not traveled out of her home area or visited any agricultural fair or farm and did not remember any insect bites.

Results

Parasitic debris, initially thought consistent with the external cuticle of a fly larva such as Oestrus Ovis [Sheep bot fly], was suspected but consultation with the Center for Disease Control resulted in an unexpected diagnosis of inflammation residual to a Demodex folliculorum mite migration into conjunctival stroma.

Discussion

Two species of ectoparasite arthropod mites Demodex Folliculorum and Demodex Brevis commonly infest human eyelids and skin generally (demodicosis) worldwide [1-4]. Most frequently, as in the examples here, (Figure 6, 7) they are incidental findings during biopsy for various other reasons. D. folliculorum (length 0.3-0.4 mm) commonly in eyelid or body hair follicles and D. brevis (length 0.15-0.2 mm) preferring the sebaceous Zeis glands associated with eyelid hair follicles or sebaceous glands of the face and chest. D. brevis is also thought capable of destroying meibomian glands [1]. Although usually asymptomatic, the more common D. folliculorum may be associated with chronic blepharitis and may aggravate lid hyperemia, meibomian inflammation, chalazion formation, dry eye, and Rosacea [1]. Clinical signs include distension and increased fragility of cilia follicles and debris collars around the bases of eyelashes. A 2013 publication by Huang et al. suggested these infestations may increase recurrence of pterygia after excision [5]. Demodex infestation has a strong association with various types of dermatitis including rosacea and acne. Based on recent genetic studies of mitochondrial DNA it seems the human variety of D. folliculorum has a common ancestry with similar mites of dogs [6]. Of interest, the life cycle of D. folliculorum is only approximately one week. It feeds primarily on blood or plasma, the secretions of sebaceous glands and epithelial cells [1]. Females lay 20-24 eggs of 50–60-micron length. The hatchlings morph into nymphs and then pass through two stages into adults. They avoid sunlight and are generally only actively mobile at night, moving at approximately 16 mm/hour. Their aversion to light causes them to retract into cilia spaces during slit lamp examination making it unlikely they can be viewed by the examiner. D. folliculorum has dagger-like teeth capable of penetrating the host cells and in addition can secrete lytic enzymes to predigest its food [1]. While obviously a superbly adapted parasite deserving respect for its survival ability, D. folliculorum causes direct damage to human hair follicles, and dermal epithelium. D. brevis can block meibomian glands causing granulomatous inflammation secondary to chitin debris, perhaps a significant unrecognized contribution to chalazion occurrence [1]. Mites may also be associated with bacterial species including Propionibacterium and Staphylococcus aureus that play substantial roles in many serious dermatologic diseases.