Hypertrophic Lichen Planus–Like Reactions Combined With Infundibulocystic Hyperplasia

Use of proliferation rate, p53 staining and perforating elastic fibers in distinguishing keratoacanthoma from hypertrophic lichen planus: a pilot study

“…Kossard et al have reported localized hypertrophic LP‐like reactions that do not progress to typical LP, but may show ‘infundibulocystic hyperplasia’ that may progress to KA or ‘infundibulocystic’ SCC. These patients responded rapidly to oral retinoids, highlighting the importance of recognizing hypertrophic lichenoid reactive processes (including hypertrophic LP) that may be amenable to medical rather than surgical therapy 8 …”

Keratoacanthoma and Infundibulocystic Squamous Cell Carcinoma

“…We have also encountered an eruptive multinodular presentation of keratoacanthoma that may have a violaceous lichenoid element, often localized to the lower limbs of elderly individuals and clinically may resemble hypertrophic lichen planus. 11 The controversy is particularly polarized with regard to the histopathology of keratoacanthoma and its relationship to squamous cell carcinoma. In practice, there is a significant number of keratoacanthomas that have a histological component that is indistinguishable from squamous cell carcinoma represented as cords or micronodules of pleomorphic keratinocytes developing particularly at the base of the tumor.…”

“…The capacity of retinoids to promote follicular differentiation has led to successful outcomes in managing unusual forms of keratoacanthoma that are not amenable to surgery 28 including giant forms of progressive growth, eruptive forms including multiple keratoacanthomas occurring in sun-damaged skin over the lower legs, and a subset that shares features with hypertrophic lichen planus. 11 Ultimately, any detailed study of the biological pathways governing the development and involution of keratoacanthoma and less well-differentiated infundibulocystic carcinomas will have to be linked with clinical, histopathological, and biological behavior of these tumors. The finding that ominous perineural or even intravenous involvement in keratoacanthoma of the lip 29,30 and other sites 31,32 does not carry the same guarded prognosis as bona fide squamous cell carcinoma indicate that the biological outcome of keratoacanthomas may be altered by their follicular derivation and overwhelming capacity to involute.…”

Keratoacanthoma en plaque/nodule: A brief report of the clinicopathological features of five cases

“…A case of KA en plaque with a large verrucous plaque studded with small nodules (eruptive keratoacanthoma forming a large plaque) has also been reported . The reported cases under the description “hypertrophic lichen planus‐like reactions with infundibulocystic follicular hyperplasia” (the authors thought that these lesions might be either KA or infundibulocystic SCC) are considered to be examples of KA en plaque at the early/proliferative stage; these cases show the clinical features of verrucous/keratotic plaques, similar to the five lesions reported here …”

“…Keratoacanthoma is characterized by exoendophytic growth with a central keratin‐filled crater, representing the crateriform architecture. However, rare cases of KA that clinically show plaque lesions have been reported, often termed “KA en plaque” . KA en plaque is not yet widely known, and few reports with a sizable number of cases have described its clinicopathological features.…”