From the Boston University School of Medicine (AC); the Department of Ophthalmology (SKF, AR), Boston Medical Center, Boston University School of Medicine; and the Department of Pathology (NL), Ocular Pathology Laboratory, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Suzanne K. Freitag, MD, 720 Harrison Avenue, DOB 10 Boston, MA 02118. E-mail: Suzanne.Freitag@bmc.org
Epidermal inclusion cysts are benign subcutaneous lesions commonly found in the eyelid region. They may expand slowly over months to years due to accumulation of desquamated debris, primarily keratin. A pore may develop in the anterior surface of the cyst where keratin may be expressed. These lesions may be present for many years without consequence.
Epidermal inclusion cysts of the eyelid are common; however, infection is rarely reported in the literature. We report an unusual case of a 72-year-old woman with a history of bilateral upper eyelid epidermal inclusion cysts of greater than 7 years’ duration who presented with acute infection with abscess formation caused by anaerobic gram-positive cocci within a preexisting epidermal inclusion cyst of the left upper eyelid.
A 72-year-old woman presented with a 3-day history of an enlarging, painful mass in the nasal aspect of the left upper eyelid. She had undergone a routine eye examination 5 days prior by her optometrist, who had documented bilateral medial upper eyelid cysts. The patient stated the lesions had been present for longer than 7 years and had caused her no problems previously. Her medical history was significant for glaucoma, myocardial infarction, coronary artery disease, hyperlipidemia, hypertension, peripheral vascular disease, and gastritis and she was taking atenolol, simvastatin, aspirin, nitroglycerin, and omeprazole.
On examination, visual acuity was 20/30 in the right eye and 20/40 in the left eye. Pupils, extraocular motility, and intraocular pressures were within normal limits. Slit-lamp biomicroscopy of the anterior segments was within normal limits. Externally, she had a tender, erythematous, edematous, fluctuant 12 × 7-mm mass of the left upper eyelid consistent with abscess with surrounding preseptal cellulitis (Fig. A). A small pore was noted on the anterior surface of the abscess. The right upper eyelid had three confluent cystic lesions with keratin plugs consistent with epidermal inclusion cysts.
Figure. (A) At Presentation, the Nasal Aspect of the Left Upper Eyelid Is Erythematous with a Fluctuant Mass Containing an Anterior Pore Plugged with Keratin (arrow). Arrowheads Indicate Two Areas of Purulent Material Visible Through Thinned Skin. (B) Two Weeks Later, at the Time of Excision, the Left Upper Eyelid Abscess Has Shrunk and the Uninflamed Right Upper Eyelid Lesions Appear Unchanged. (C) Histopathology Is Consistent with an Inflamed Epidermal Inclusion Cyst. A Cystic Cavity Containing Keratin Debris Is Lined by Squamous Epithelium. The Cyst Wall Contains Chronic Inflammation (hematoxylin–Eosin, Original Magnification ×4).
The abscess was drained by applying pressure with cotton tip applicators and expressing first a small whitish plug consistent with keratin and then nearly 1 cc of yellow purulent material. Cultures were obtained and the patient was empirically treated with oral amoxicillin/clavulanate potassium. At the 1-week follow-up, the surrounding cellulitis had resolved but a small amount of purulent material was expressed from the deflated, mildly erythematous cystic cavity. Cultures grew anaerobic gram-positive cocci. She returned 1 week later for excisional biopsy of right and left upper eyelid lesions (Fig. B). Histopatholologic examination revealed bilateral epidermal inclusion cysts. The cysts were lined by a keratinizing squamous epithelium, focally ruptured, showing chronic foreign body type granulomatous inflammation with giant cells. Gram stain for bacteria was negative (Fig. C).
Epidermal inclusion cysts are slow-growing, firm, mobile, round or oval intradermal or subcutaneous lesions, most commonly found in the face, scalp, neck, and trunk. A pore may be present on the anterior surface tethering the cyst to the overlying epidermis. Epidermal inclusion cysts arise as a proliferation of epidermal cells within a circumscribed space of the dermis. The source of epidermal cells is often the infundibulum of hair follicles. The cyst walls are lined with squamous epithelium. Epidermal inclusion cysts expand slowly, often over years, due to accumulation of keratinous material, which may be expressed through the pore.
These lesions may become infected or inflamed, and abscess formation may occur.1,2 A review of the literature did not reveal any cases of infected epidermal inclusion cysts of the eyelid; however, there was mention of two “ocular” cases in one series.1 There is another report of an infected conjunctival epidermal inclusion cyst after a strabismus surgery.3 Management included surgical drainage and systemic antibiotics. The lesion may recur if the cyst lining, which is responsible for the keratin production, is not completely excised.
Gram-positive anaerobic cocci were isolated in our case, and these organisms are common normal flora in humans, accounting for 25% to 30% of all anaerobic isolates from human specimens.4 Gram-positive anaerobic cocci are most frequently found in the mouth, upper respiratory and gastrointestinal tracts, female genitourinary system, and skin. Gram-positive anaerobic cocci are a heterogeneous group of organisms defined by their morphology and inability to grow in oxygen-rich environments. Most clinical isolates of gram-positive anaerobic cocci belong to the genus Peptostreptococcus, which is a genetically and phenotypically diverse group. Many microbiology laboratories do not routinely identify the species.4
Several studies have examined the flora of epidermal inclusion cysts. Brook1 cultured infected epidermal inclusion cysts and 192 of 231 grew organisms. There were aerobes only in 44%, anaerobes only in 30%, and mixed aerobes and anaerobes in 26%. Of the 41 epidermal inclusion cysts involving the head in this study, 29% grew aerobes only, 44% grew anaerobes only, and 27% grew a mixture. Most anaerobic isolates (20 of 41) from the head region epidermal inclusion cysts grew Peptostreptococcus species.
One criticism of Brook’s study was the lack of a control group. As a result, Diven et al.2 compared flora from inflamed versus uninflamed epidermal inclusion cysts. The two groups had similar culture results. Of the inflamed and uninflamed epidermal inclusion cysts, 14 of 25 cultures in both groups grew anaerobes, with 50% of these being Peptostreptococcus species. In the inflamed group, 25 of 25 aerobic cultures grew bacteria. In the uninflamed group, 22 of 25 aerobic cultures grew bacteria. Coagulase-negative Staphylococcus was the most common organism in both of these groups.
Presumably these cysts are colonized because of the connection with overlying skin either directly through a pore in the anterior cyst wall or via a hair follicle or eccrine duct. Finegold5 stated, “Virtually the only source of anaerobes participating in infection is the indigenous flora of mucosal surfaces and, to a much lesser extent, the skin” (p. 3). Hence, the most likely source of infection in our patient was her normal anaerobic flora.
- Brook I. Microbiology of infected epidermal cysts. Arch Dermatol. 1989;125:1658–1661. doi:10.1001/archderm.125.12.1658 [CrossRef]
- Diven DG, Dozier SE, Meyer DJ, Smith EB. Bacteriology of inflamed and uninflamed epidermal inclusion cysts. Arch Dermatol. 1998;134:49–51. doi:10.1001/archderm.134.1.49 [CrossRef]
- Khan AO, Al-Katan H, Al-Baharna I, Al-Wadani F. Infected epithelial inclusion cyst mimicking subconjunctival abscess after strabismus surgery. J AAPOS. 2007;11:303–304. doi:10.1016/j.jaapos.2006.07.007 [CrossRef]
- Murdoch DA. Gram-positive anaerobic cocci. Clin Microbiol Rev. 1998;11:81–120.
- Finegold SM. Anaerobic infections in humans: an overview. Anaerobe. 1995;1:3–9. doi:10.1016/S1075-9964(95)80340-8 [CrossRef]