Keratosis Lichenoides Chronica: Proposal of a Concept

Autoinflammatory Keratinization Diseases-The Concept, Pathophysiology, and Clinical Implications

Recent advances in medical genetics elucidated the background of diseases characterized by superficial dermal and epidermal inflammation with resultant aberrant keratosis. This led to introducing the term autoinflammatory keratinization diseases encompassing entities in which monogenic mutations cause spontaneous activation of the innate immunity and subsequent disruption of the keratinization process. Originally, autoinflammatory keratinization diseases were attributed to pathogenic variants of CARD14 (generalized pustular psoriasis with concomitant psoriasis vulgaris, palmoplantar pustulosis, type V pityriasis rubra pilaris), IL36RN (generalized pustular psoriasis without concomitant psoriasis vulgaris, impetigo herpetiformis, acrodermatitis continua of Hallopeau), NLRP1 (familial forms of keratosis lichenoides chronica), and genes of the mevalonate pathway, i.e., MVK, PMVK, MVD, and FDPS (porokeratosis). Since then, endotypes underlying novel entities matching the concept of autoinflammatory keratinization diseases have been discovered (mutations of JAK1, POMP, and EGFR). This review describes the concept and pathophysiology of autoinflammatory keratinization diseases and outlines the characteristic clinical features of the associated entities. Furthermore, a novel term for NLRP1-associated autoinflammatory disease with epithelial dyskeratosis (NADED) describing the spectrum of autoinflammatory keratinization diseases secondary to NLRP1 mutations is proposed.

Confluent and Reticulated Papillomatosis of Gougerot and Carteaud: A Case Report and Review of the Literature

Confluent and reticulated papillomatosis (CARP) of Gougerot and Carteaud is a rare chronic disease with exacerbation and remissions typically affecting young people. Classic clinical characteristics include asymptomatic scaly hyperpigmented macules, patches, and papules in the trunk's confluent and reticular pattern. A 12-year-old girl, otherwise healthy, presented with itchy, persistent skin lesions all over her body for one year. Skin examination revealed generalized scaly brownish patches, thin papules, and plaques all over her body, including her face, neck, middle of the chest, abdomen, back, upper extremities, elbows, lower extremities, and knees. Wood's lamp examination of her skin lesions was unrevealing. Skin biopsy showed papillomatosis, hyperkeratosis, acanthosis, and hypergranulosis. The dermis showed perivascular inflammatory cellular infiltrate. Based on the above clinicopathological findings, the patient was diagnosed with CARP. In our case, a generalized form was reported. CARP is diagnosed based on clinical and histopathological features. Oral antibiotics are the cornerstone of treatment. Our patient responded well to oral minocycline 85 mg one tablet daily, tacrolimus 0.1% ointment twice daily, and selenium sulfide shampoo twice weekly for two months. The classic clinical characteristics of CARP include asymptomatic scaly hyperpigmented macules, patches, and papules in a confluent and reticular pattern on the trunk. A generalized form, as in our case, has been reported. CARP is diagnosed based on clinical and histopathological features. Oral antibiotics are the cornerstone of treatment.

Cutaneous signs and mechanisms of inflammasomopathies

The emerging group of autoinflammatory diseases (AIDs) is caused by a dysregulation of the innate immune system while lacking the typical footprint of adaptive immunity. A prominent subgroup of AIDs are inflammasomopathies, which are characterised by periodic flares of cutaneous signs as well as systemic organ involvement and fever. The range of possible skin lesions is vast, ranging from urticarial, erysipelas-like and pustular rashes to erythematous patches, violaceous plaques and eventual necrosis and ulceration. This review provides a structured overview of the pathogenesis and the clinical picture with a focus on dermatological aspects of inflammasomopathies. Current treatment options for these conditions are also discussed.

Adnexotropic Variants of the Interface Dermatitides: A Review

The interface dermatitides encompass a vast array of cutaneous entities which, at times, may present with particular clinical variants with adnexal predilection. Similarly, hair follicle and eccrine gland involvement of some of these entities has been observed on histopathology. This review aims to describe the various adnexotropic presentations of the interface dermatitides. Recognizing that the adnexa can be a frequent site of involvement of these conditions may aid dermatopathologists in making the correct diagnosis and avoid misinterpreting adnexotropism for other conditions such as the great imitator, mycosis fungoides.

Erythema ab igne with features resembling keratosis lichenoides chronica

Erythema ab igne (EAI) is an asymptomatic dermatosis that develops in response to chronic exposure to low-grade heat. Characteristic findings on histopathology include epidermal atrophy, dermal elastosis, atypical histiocytes, and melanin and hemosiderin deposition. Reactive endothelial changes and prominent vascular proliferation are variable. Keratosis lichenoides chronica (KLC) is a rare lichenoid hyperkeratotic dermatosis. Acanthosis with parakeratosis and a lichenoid interface dermatitis with lymphocytes, histiocytes, and plasma cells are characteristic findings of KLC. Although its etiology remains unclear, KLC has been reported to occur in response to heat. Herein, we report a case of EAI with features resembling KLC.

Fixed drug eruptions, bullous drug eruptions, and lichenoid drug eruptions

Drug reactions are among the most common reasons for inpatient dermatology consultation. These reactions are important to identify because discontinuation of the offending agent may lead to disease remission. With the rising use of immunomodulatory and targeted therapeutics in cancer care and the increased incidence in associated reactions to these drugs, the need for accurate identification and treatment of such eruptions has led to the development of the "oncodermatology" subspecialty of dermatology. Immunobullous drug reactions are a dermatologic urgency, with patients often losing a significant proportion of their epithelial barrier; early diagnosis is critical in these cases to prevent complications and worsening disease. Lichenoid drug reactions have myriad causes and can take several months to occur, often leading to difficulties identifying the offending drug. Fixed drug eruptions can often mimic other systemic eruptions, such as immunobullous disease and Stevens-Johnson syndrome, and must be differentiated from them for effective therapy to be initiated. We review the clinical features, pathogenesis, and treatment of immunobullous, fixed, and lichenoid drug reactions with attention to key clinical features and differential diagnosis.

'Hints' in the horn: diagnostic clues in the stratum corneum

The stratum corneum or horny layer is the uppermost layer of the epidermis, and is mainly responsible for the skin's barrier function. In spite of its complexity at the ultrastructural and molecular level, the features accessible to visualization on conventional histology are relatively limited. Nevertheless, knowledge of subtle clues that one may observe in the stratum corneum can prove useful in a wide range of situations in dermatopathology. We herein review a selection of common and rare entities in which the horny layer may reveal significantly important hints for the diagnosis. These clues include parakeratosis and its different patterns (focal, confluent, alternating, associated with spongiosis, epidermal hyperplasia or lichenoid changes), subcorneal acantholysis, infectious organisms in the stratum corneum (including fungal, bacterial and parasitic), thickening or thinning of the stratum corneum and the presence of different kinds of pigment. Even when normal, the horny layer may prove to be useful when seen in association with severe epidermal damage, a combination of features testifying to the acute nature of the underlying pathological process.

Nekam's disease

Keratosis lichenoides chronica also known as Nekam's disease is a rare mucocutaneous disorder, characterized clinically by asymptomatic violaceous keratotic papules arranged in linear, reticular, or plaque form usually on the trunk and extremities and histologically by interface dermatitis. The disease is considered rare with only 128 cases being reported in the literature till date and very few from India. We report a case of a 40-year-old man who presented with constellation of features of lichen planus, seborrheic dermatitis, and apthous ulcers, which upon workup was found to be Nekam's disease.

Lichen planus and other lichenoid dermatoses: Kids are not just little people

Lichenoid dermatoses, a group of inflammatory skin conditions with characteristic clinical and histopathologic findings, range from common to rare. Classic lichen planus typically presents as pruritic, polygonal, violaceous flat-topped papules and plaques; many variants in morphology and location also exist. Other lichenoid dermatoses share similar clinical presentations and histopathologic findings. These include lichenoid drug eruption, lichen planus-like keratosis, lichen striatus, lichen nitidus, and keratosis lichenoides chronica. Epidemiologic characteristics vary among each lichenoid disorder. While classic lichen planus is considered a disease of adults, other lichenoid dermatoses may be more common in younger populations. The literature contains an array of reports on the variations in presentation and successful management of lichen planus and lichenoid dermatoses among diverse populations. Familiarity with the characteristics of each lichenoid dermatosis, rare or common within each patient population, is key to accomplishing timely recognition and effective management.

A Mild Case of Adult-Onset Keratosis Lichenoides Chronica Successfully Treated with Narrow-Band UVB Monotherapy

Keratosis lichenoides chronica (KLC) is a rare keratotic disorder of unknown origin. Effective treatment has not been established yet. Here, we present adult-onset KLC, which was treated by narrow-band ultraviolet B (NB-UVB) monotherapy. Although NB-UVB was reported to be effective for pediatric-onset KLC, it has not been clear if this regimen is also useful for adult-onset type because pediatric-onset KLC is suggested to be different in nature. We assume that KLC is treatable by NB-UVB regardless of the age of the patient.

Pediatric onset keratosis lichenoides chronica: a case report

Keratosis lichenoides chronica (KLC) is an acquired keratinization disorder that is rare in childhood. We report a case of sporadic pediatric-onset KLC with seborrheic dermatitis-like lesions on the forehead, papules in a retiform pattern in the axillae and mons pubis, and eye and oral mucosal involvement,with additional features of premature canities and a transient photosensitive eruption.

Queratose liquenoide crônica: relato de caso

A queratose liquenoide crônica ou doença de Nekam é uma dermatose mucocutânea rara da queratinização, com curso crônico e progressivo, que acomete geralmente indivíduos entre 20 e 40 anos. Existem, aproximadamente, 70 casos descritos na literatura. Devido à raridade desta dermatose e à ausência de tratamento efetivo, é uma doença de difícil manejo. No caso em questão, apresentamos um paciente de 42 anos com pápulas violáceas, hiperqueratósicas, algumas confluentes, com aspecto linear, rendilhado e em placas, localizadas no tronco e membros há cinco anos. Lesões aftoides na cavidade oral e úlceras rasas na genitália também faziam parte do quadro. O anatomopatológico foi bastante sugestivo de queratose liquenoide crônica. Introduziu-se tratamento com acitretina e dapsona, havendo melhora parcial do quadro

[Keratosis lichenoides chronica in two siblings with marked response to UVB phototherapy]

BACKGROUND

Keratosis lichenoides chronica (KLC) is a rare chronic keratinisation disorder. Out of almost 60 published cases of KLC, only two report its occurrence in siblings. We report a new case in which a brother and sister present KLC that improved markedly with UVB phototherapy.

PATIENTS AND METHODS

A 10-year-old girl presented with hyperkeratotic papules symmetrically arranged in a reticular pattern on the face and the extremities. Onset occurred at the age of six months. For a number of years, minimum sunlight was allowed owing to a diagnosis of lupus. However, KLC was our first diagnostic assumption, confirmed by an elbow lesion biopsy sample. The patient's brother, one and a half years old, had been presenting similar lesions since the age of two months. Sibship was demonstrated by DNA analysis using short tandem repeat markers. No consanguinity was found. After one month of narrow-band UVB phototherapy, most of the papules had flattened.

DISCUSSION

KLC is uncommon in childhood and familial occurrence is very rare. Clinically, thick keratotic papules arranged in parallel lines or small networks cover the dorsal aspects of the limbs symmetrically. The face may be affected by a seborrhoea-like dermatitis. Histology typically shows alternating acanthosis and atrophy, with focal parakeratosis. An extensive lichenoid lymphohistiocytic and plasmocytic infiltrate is demonstrated in the dermis. The course is chronic. Spontaneous resolution may occur. Sunlight has been shown to be effective in the few paediatric cases reported. Narrow-band UVB phototherapy appears to be an effective therapeutic option.