Linear nevus comedonicus with epidermolytic hyperkeratosis

Post Zygotic, Somatic, Deletion in KERATIN 1 V1 Domain Generates Structural Alteration of the K1/K10 Dimer, Producing a Monolateral Palmar Epidermolytic Nevus

Palmoplantar keratodermas (PPKs) are characterized by thickness of stratum corneum and epidermal hyperkeratosis localized in palms and soles. PPKs can be epidermolytic (EPPK) or non epidermolytic (NEPPK). Specific mutations of keratin 16 (K16) and keratin 1 (K1) have been associated to EPPK, and NEPPK. Cases of mosaicism in PPKs due to somatic keratin mutations have also been described in scientific literature. We evaluated a patient presenting hyperkeratosis localized monolaterally in the right palmar area, characterized by linear yellowish hyperkeratotic lesions following the Blaschko lines. No other relatives of the patient showed any dermatological disease. Light and confocal histological analysis confirmed the presence of epidermolityic hyperkeratosis. Genetic analysis performed demonstrates the heterozygous deletion NM_006121.4:r.274_472del for a total of 198 nucleotides, in KRT1 cDNA obtained by a palmar lesional skin biopsy, corresponding to the protein mutation NP_006112.3:p.Gly71_Gly137del. DNA extracted from peripheral blood lymphocytes did not display the presence of the mutation. These results suggest a somatic mutation causing an alteration in K1 N-terminal variable domain (V1). The deleted sequence involves the ISIS subdomain, containing a lysine residue already described as fundamental for epidermal transglutaminases in the crosslinking of IF cytoskeleton. Moreover, a computational analysis of the wild-type and V1-mutated K1/K10 keratin dimers, suggests an unusual interaction between these keratin filaments. The mutation taster in silico analysis also returned a high probability for a deleterious mutation. These data demonstrate once again the importance of the head domain (V1) of K1 in the formation of a functional keratinocyte cytoskeleton. Moreover, this is a further demonstration of the presence of somatic mutations arising in later stages of the embryogenesis, generating a mosaic phenotype.

Late-Onset Nevus Comedonicus With Follicular Epidermolytic Hyperkeratosis-Case Report and Review of the Literature

Nevus comedonicus is a rare cutaneous follicular hamartoma, characterized by the clustering of papules with firm, blackened horny buffers. It is usually present at birth or during childhood, although few cases of late-onset disease have been described. We present a case of postmenopausal-onset nevus comedonicus in a 55-year-old white woman without relevant medical history. Skin biopsy showed the typical features of several cyst-dilated follicular structures occupied by keratotic material and the peculiar finding of epidermolytic hyperkeratosis of the follicular epithelial walls. A brief review of the clinical and histological features of other similar cases published in the literature is performed.

Epidermal nevus syndromes

The term epidermal nevus syndrome (ENS) has been used to describe the association of epidermal hamartomas and extracutaneous abnormalities. Although many continue to use the term "ENS," it is now understood that this is not one disease, but rather a heterogeneous group with distinct genetic profiles defined by a common cutaneous phenotype: the presence of epidermal and adnexal hamartomas that are associated with other organ system involvement. One commonality is that epidermal nevi often follow the lines of Blaschko and it appears the more widespread the cutaneous manifestations, the greater the risk for extracutaneous manifestations. The majority of the extracutaneous manifestations involve the brain, eye, and skeletal systems. The CNS involvement is wide ranging and involves both clinical manifestations such as intellectual disability and seizures, as well as structural anomalies. Several subsets of ENS with characteristic features have been delineated including the nevus sebaceus syndrome, Proteus syndrome, CHILD syndrome, Becker's nevus syndrome, nevus comedonicus syndrome, and phakomatosis pigmentokeratotica. Advances in molecular biology have revealed that the manifestations of ENS are due to genomic mosaicism. It is likely that the varied clinical manifestations of ENS are due in great part to the functional effects of specific genetic defects. Optimal management of the patient with ENS involves an interdisciplinary approach given the potential for multisystem involvement. Of note, epidermal nevi have been associated with both benign and malignant neoplasms, and thus ongoing clinical follow-up is required.

Epidermolytic hyperkeratosis in inflammatory linear verrucous epidermal nevus

Epidermolytic hyperkeratosis presents with perinuclear vacuolization of the keratinocytes in spinous and granular layers, keratinocytes with ill-defined limits, which leads to a reticulate appearance of the epidermis, an increased number of variously shaped and sized basophilic keratohyalin granules and the same sized eosinophilic trichohyalin granules, at any level of epidermis, mainly in the stratum granulosum, and compact hyperkeratosis. This minor reactive pathologic reaction pattern of skin is found in large variety of diseases. This paper is the first case report of such pattern in inflammatory linear verrucous epidermal nevus. Our case is of a 23-year-old man with pruritic verrucous lesions of trunk and extremities initiated since 13 years ago. Physical examination revealed white linear hyperkeratotic lesions, some of them on erythematous background and also classic epidermal nevus. No skeletal, ophthalmic, and nervous system involvement was detected. Microscopic study of pruritic verrucous lesions showed psoriasiform acanthosis, mild papillomatous, hyperkeratosis, and epidermolytic hyperkeratotic changes in hair follicles and acrosyrinx accompanied with moderate perivascular inflammation.

Linear morhpea, nevus comedonicus, and lichen striatus in a 5-year-old girl

Linear morphea, lichen striatus, and nevus comedonicus are rare conditions. We describe a five-year-old girl in whom all three of these dermatoses are present.

Naevus comedonicus: a spectrum of body involvement

Naevus comedonicus (NC) is a rare developmental anomaly, with < 200 cases reported in the literature. It usually occurs on the face, neck or chest, appearing as groups of closely arranged dilated follicular openings with keratin plugs. Several associations have been made in the literature. We review the current literature, emphasizing the clinical features, associated conditions and therapeutic options.

Cytokeratin and filaggrin expression in nevus comedonicus

To elucidate the pathogenesis of abnormal keratinization in nevus comedonicus, we performed an immunohistochemical study using antikeratin and antifilaggrin (filament-aggregating protein) antibodies. There were no significant differences between nevus comedonicus and normal skin in cytokeratin expression. Although filaggrin was only detected in the granular layer in open comedones, filaggrin was detected in both superficial cells and also intermediate cells in closed comedones, suggesting that filaggrin is involved in the formation of closed comedones. The disorder of terminal differentiation related to filaggrin may play a role in the pathogenesis of abnormal keratinization in nevus comedonicus.