Keratinous Cyst, Intratarsal
Key Points
Intratarsal keratinous cysts arise from the meibomian glands of the tarsal plates
They do not arise from the dermis, and therefore are distinct from epidermoid cysts of the eyelid
80% are located in the upper eyelids without a history of trauma, inflammation, previous eyelid surgery, or preexisting lesions
The etiology of these cysts is unclear, but blockage of meibomian ducts appears to be responsible for their formation
They present as a yellow-white to skin-colored, smooth, well-circumscribed, noninflammatory lesion that can appear as a prominent bulge beneath the eyelid skin over the tarsus, or may only be detectable when the eyelid is everted
Treatment includes complete excision of the entire cyst, exposure of the capsule, amputation from the tarsus, and generous cautery at the base wall to prevent a recurrence
With inadequate excision or drainage, the recurrence rate is high, but with complete excision the prognosis is excellent
Intratarsal keratinous cysts (IKC) are a recently described entity that arises from the meibomian glands of the tarsal plates.1,2 After chalazion and sebaceous carcinoma, IKC is the third most common cause of primary tarsal swelling.1 This lesion has also been referred to in the literature as a tarsal keratinous cyst, intratarsal inclusion cyst, intratarsal epidermal inclusion cyst, meibomian gland ductal cyst, epidermal cyst, and epidermoid cyst.1,3,4,5,6,7,8 However, these lesions arise within the meibomian glands of the tarsal plates, not from the dermis, and therefore are distinct from epidermoid cysts of the eyelid.
The term “intratarsal keratinous cyst” was introduced by Jakobiec et al1 based on six cases and a review of cases previously described in the literature as intratarsal inclusion cyst.3 All of these cases were characterized by progressive growth of a mostly palpable cystic lesion on the eyelid fixed to the tarsus. Larger series were subsequently described by Kim et al9 who added 11 cases, and Zhang et al10 who reported 15 new cases lacking external signs on the eyelid skin. Among all of these cases, the incidence was equal between men and women, and only 7% of patients were younger than 20 years of age. To date, only 59 cases have been described, although, among 35 cases of all eyelid cysts, Suimon et al11 diagnosed IKC in 14%, so that the incidence may be higher than appears in the literature.
About 80% of IKCs are located in the upper eyelids, and typically there is no history of trauma, inflammation, previous eyelid surgery, or preexisting lesions. The mean age at presentation has been reported to be 45 to 68 years,1,9,10,11 and there is no gender predilection.
Patients usually present with an eyelid lump that may have been present for several months to up to 5 years. Initial diagnosis is frequently missed, usually made as a more common lesion such as chalazion. Patients most commonly present with complaints of a foreign body sensation, but pain and epiphora are rare symptoms reported in only about 20% of cases.10
Etiology and Pathogenesis
The etiology of IKC and other eyelid cysts is not clear, but previously they were considered to result as a complication of previous eyelid surgery.12,13 However, attachment of the cysts to the tarsus as well as the histopathology and immunohistochemistry suggests that these lesions originate from the meibomian glands or their ducts. Meibomian gland ducts are lined with keratinizing stratified squamous epithelium without a granular layer and with an innermost cuticle layer,14,15 similar to the lining of IKC. Also, both IKC and meibomian ducts stain positive for epithelial membrane antigen (EMA) on immunohistochemistry. Blockage of these ducts appears to be responsible for the formation of IKCs.10 IKC is distinct from a chalazion, which is a chronic granulomatous inflammatory lesion of the meibomian gland or gland of Zeiz resulting from lipid breakdown products leaking into surrounding tissues.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
