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Author: Cathlyna Saavedra, Medical Student, University of Auckland, Auckland, New Zealand. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. May 2019.
Keratosis lichenoides chronica describes violaceous keratotic papules and nodules arranged in a linear or reticulate pattern on the trunk and limbs, in association with a seborrhoeic dermatitis-like eruption on the face [1,2].
Keratosis lichenoides chronica is also called Nekam disease, lichen verrucosus et reticularis, lichenoid tri-keratosis, keratose lichenoide striae, porokeratosis striata, morbus moniliformis, and lichen ruber moniliformis.
Keratosis lichenoides chronica is rare, with only around 70 cases reported in the medical literature (2019) . It can occur in people of any race, age, or sex. The majority of cases have been described in adults aged 20–40 years; 24% were children . The male to female ratio is 1.73 . Most reported cases are Caucasians.
The cause of keratosis lichenoides chronica is not well understood. It was previously thought to be a rare variant of lichen planus, but many now consider it to be a distinct condition .
Some familial cases of keratosis lichenoides chronica are due to a germline mutation in NLRP1, an inflammasome sensor gene which activates inflammatory cytokines. The aberrant activation of NLRP1 leads to the localised release of interleukin (IL)-1, secondary secretion of tumour necrosis factor-alpha (TNF-α) and keratinocyte growth factor (KGF), resulting in epidermal hyperplasia and keratosis [3,4].
Keratosis lichenoides chronica is characterised by brownish-purple, thick scaly papules or small nodules on the trunk and extremities. The papules are generally arranged in a linear or reticular pattern and are symmetrically distributed. They are usually asymptomatic but can be itchy in 20% of cases. Keratosis lichenoides chronica has a chronic and often progressive course .
In 70% of cases, patients also present with facial lesions resembling seborrhoeic dermatitis or rosacea. The lesions are papules or plaques with variable hyperkeratotic scaling that tend to be localised to the convex areas of the face. The nasolabial folds are almost always spared .
Other features associated with keratosis lichenoides chronica include :
Complications of keratosis lichenoides chronica include visual impairment from ocular manifestations and secondary bacterial infection .
Criteria for diagnosing keratosis lichenoides chronica have not been well established .
The main differential diagnosis is lichen planus; the features distinguishing keratosis lichenoides chronica from lichen planus are the absence of pruritus, a lack of response to a topical or systemic corticosteroid, and the presence of focal parakeratosis in histological samples.
A skin biopsy is recommended for the histological diagnosis of keratosis lichenoides chronica. Histology typically shows:
Direct immunofluorescence is typically negative .
Several other conditions can present with pigmented papules and lichenoid histology.
Cutaneous lupus is typically photosensitive, whereas keratosis lichenoides chronica generally improves with sun exposure .
Keratosis lichenoides chronica is very resistant to available therapies. A recent review found that most patients experience improvement with sun exposure and that oral retinoids (eg, acitretin) and phototherapy, specifically photochemotherapy (PUVA), either alone or in combination, are the most effective treatments .
Topical agents such as steroid creams are usually ineffective. Systemic agents that have been reported to be useful in some patients include:
Keratosis lichenoides chronica is very difficult to treat, and in most cases, remission is never achieved. The complete resolution has never been reported .
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