The bulbar conjunctiva is involved, especially in the nasal and temporal perilimbal region. The oral lesions, which are typically asymptomatic and may go unrecognized, usually appear as thick, soft, white papules and plaques of various sizes, involving any part of the oral cavity. The ocular manifestations in this condition vary in severity from asymptomatic plaques on the bulbar conjunctiva to complete involvement of the cornea with severe vision loss. Patients commonly complain of symptoms of irritation, such as erythema, itching, excessive lacrimation, and photophobia. Periods of acute intensification of symptoms are common, especially in the spring. The lesions may become apparent in early infancy and may date from birth.
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Excerbation and recurrence after plaque excision Symptoms Bilateral, marked, red eyes is the most common symptom due to bulbar conjunctival hyperemia. Patients with HBID have reported a stigma of eye redness which is commonly confused for drug or alcohol abuse . Patients also may experience discomfort, tearing, photophobia, burning, foreign-body sensation, or decreased visual acuity.
Patients tend to have exacerbations of symptoms in the spring and summer months but alleviation in cooler weather  . Clinical diagnosis Hereditary benign intraepithelial dyskeratosis has a distinct clinical picture. Diagnosis can be made by slit lamp biomicroscopy alone. Affected patients may have ocular involvement, oral involvement, or both. Oral manifestations of the disease include white, spongy plaques of the buccal mucosa, tongue, or lips .
Ocular manifestation of the disease is characterized by bilateral, conjunctival injection with whitish-gray, elevated, gelatinous corneal plaques located in the perilimbal area, most often nasally or temporally   .
The corneal plaques may become visually significant with extension into the central visual axis, disruption the normal ocular surface, or induction of astigmatism. Corneal neovascularization can occur around areas of plaque formation. Most commonly, neovascularization develops superficially, but involvement of the mid to deep stroma has been reported . Although originally thought to be congenital, HBID is not present at birth.
Symptoms begin in early childhood and follow a waxing and waning pattern throughout life. Few reports have suggested that plaques spontaneously shed, however there has never been photographic documentation of this phenomenon.
Excision of plaques leads to recurrence and further exacerbation in most cases . Histopathologic diagnosis In addition to clinical diagnosis, HBID can also be diagnosed histopathologically. Ocular and oral plaques are distinctively characterized by acanthosis, dyskeratosis, and parakeratosis within the stratified squamous epithelium. The hallmark dyskeratotic cells in hereditary benign intraepithelial dyskeratosis have a dense cytoplasm and pyknotic nuclei.
Beneath the epithelium in the stroma lies a chronic, mid to moderate lymphocytic inflammatory response. The adjacent stratified squamous epithelium of the conjunctiva can be normal or acanthotic  . They observed that cells in affected HBID patients had a shift in differentiation toward keratinization. Additionally, cells contained densely packed tonofilaments in the cytoplasm, numerous vesicular structures, and disappearance of cellular desmosomes and interdigitations .
Plaque biopsy may be performed and sent for histopathologic confirmation. In , Allingham and associates were the first to discover a genetic duplication of HBID localized to chromosome 4q They studied 2 large families in North Carolina, one of which was originally studied by Carl Witkop, D. S . Of note, a gene was not localized in this region.
However, the authors proposed that a candidate gene in this region of duplication could be the human homolog of the FAT gene found in the Drosophilla fly. The FAT gene is a tumor suppressor gene that may promote abnormal epithelial cell proliferation when not functioning properly .
In , Cummings et al performed a study on 40 patients revealing that patients with a histopathologic diagnosis of HBID also had a genetic duplication 4q This study included one Haliwa-Saponi family and another family from North Carolina . However, the signs and symptoms of these two cases were more severe than the classic disease findings previously described . The corneal plaques in these patients were larger and led to severe neovascularization bilaterally, as well as total opacification in one eye.
The oral involvement was also more severe and extended to the larynx. Palmoplantar hyperkeratosis was also reported. The investigators performed whole genome sequencing on this 7-member family using negative controls from random post-PRK samples.
Using quantitative PCR, they also ruled out the duplication 4q35 in the affected patients . Differential diagnosis.
Hereditary benign intraepithelial dyskeratosis
Hereditary Benign Intraepithelial Dyskeratosis
[Hereditary benign intraepithelial dyskeratosis].