Lichenoïde Keratose Huidziekten - Alles Wat U Moet Weten

Case report

A 76-year-old man presented to our dermatology clinic with an asymptomatic single skin lesion on the right side of the temple. The patient reported that the lesion had been present for 2 weeks ( Fig 1 ). No previous skin lesions had been noted by the patient at the same site. The lesion was stable in size, color, and shape. Physical examination revealed a solitary violaceous thin plaque measuring 1.5 × 2 cm 2 . Scalp, mucosal, and nail examinations were normal. The patient was treated with 5 mg amlodipine/160 mg valsartan for hypertension and used salbutamol and budesonide/formoterol inhalers for bronchial asthma.

Solitary violaceous thin plaque on the right side of the temple at the time of presentation.

A 3-mm punch biopsy was taken from the center of the lesion, which showed interface lymphohistiocytic infiltrate with focal sawtooth rete ridges and scattered necrotic keratinocytes. Solar elastosis was also noted in the papillary dermis. There was no evidence of squamous atypia in situ or invasive malignancy ( Fig 2 ).

Photomicrography of skin punch biopsy showing interface lymphocytic infiltrate, sawtooth rete ridges, and few necrotic keratinocytes. (Hematoxylin-eosin stain, original magnification: ×200.)

Dermoscopic picture at the time of presentation.

The patient was initially treated with mometasone cream and tacrolimus ointment once daily. After 12 days of treatment, there was no change observed in the lesion, so we prescribed 5% imiquimod cream to be applied 5 days a week. The patient did not develop a reaction to the medication. After 6 weeks of treatment, he showed significant clinical improvement. No recurrence was observed after 7 months of follow-up ( Fig 4 ).

Discussion

As discussed previously, porokeratosis has varied clinical appearances, making the diagnosis difficult. The failure to include porokeratosis in the clinical differential diagnosis can lead to a failure to look for this possibility upon histologic examination. Here we show that the diagnosis of porokeratosis can be overlooked when biopsies are only partially represented on slides. For example, when there is only a subtle or absent cornoid lamella due to incomplete sampling. Such considerations are important factors for making an accurate diagnosis.

On re-review of the cases examined in this study, specific features were identified that helped define porokeratosis. These were as follows:

1. Careful inspection of consecutive levels was helpful in seeing the cornoid lamella cut into view. ( Figure 1 ) shows a cornoid lamella appearing on the edge of the specimen.

Cornoid lamella. This figure demonstrates a cornoid lamella appearing on the edge of the specimen. This came into view with additional levels. H&E with scale bar 300 µm magnification.

2. There may be a narrowing or widened gap between possible cornoid lamellae on consecutive sections ( Figure 2 ).

Cornoid lamella migrating across the specimen with deeper levels. A shows a subtle cornoid lamella within the specimen. B shows a deeper level which demonstrates the cornoid lamella cutting into clearer view and migrating across the specimen. H&E with scale bars 300 µm.

3. Areas of thinned epidermis with lichenoid inflammation adjacent to a possible cornoid lamella are a helpful diagnostic clue.

Pathogenesis

Psoriasis is considered a multifactorial immune-mediated dermatitis, with a complex and controversial pathogenesis [2], including an autoimmune component, with a variable geographical and ethnical incidence. The pathogenetic mechanisms are under the regulation of the keratinocytes, immune cells, and different cytokines, some of their changes being considered epiphenomena or later events [3].

The most frequent forms (psoriasis, pustular psoriasis, Reiter’s syndrome) share common immune-mediated mechanisms, which involve certain human lymphocyte antigens - HLA-B13, HLA-Bw17, HLA-B27, the latter being known as a major factor for the pathogenesis of ankylosing spondylitis, a chronic immune-mediated inflammatory disease with systemic involvement [4] and for Reiter’s syndrome genetic component, where the reactive disease is triggered by enteric infections, such as Chlamydia subspecies [1, 3]. The association of psoriasis and arthritis is also described in children, as juvenile psoriatic arthritis (JPsA), a rare disease in which patients can develop besides the above conditions, plantar fasciitis [5]. The genetic mechanisms in psoriasis are supported by the „allelic instability in mitosis” model [1].

Lichen simplex chronicus (LSC) is related to mechanical stimuli which are responsible for the specific pruritus, with secondary lichenification, completed by a psychogenic component [1].

For the parapsoriasis spectrum of diseases, both the relationship between large-plaque parapsoriasis and mycosis fungoides and the possibility for parapsoriasis to be part of cutaneous T-cell lymphoma are related to abnormalities of T-cell proliferation and antigen expression [1].

The considered inflammatory dermatoses are characterized by hyperproliferative epidermis due to keratinocytes hyperactivation and intense inflammatory dermic activity, especially supported by dendritic cells, neutrophils, T lymphocytes, and macrophages [3, 6]. The abnormal skin activity is managed by various proteins with different cellular activities, which are associated with the pathogenesis of the diseases, such as: signal transducer and activator of transcription (STAT), S100 proteins, Wnt family membrane 5a (Wnt5a) protein, p53/TP53 or tumor protein, enzyme biomarkers, retinoic acid related orphan nuclear receptor gamma (RORγ/RORγt), tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK), aquaporin-3 (AQP3), galectin-3, and the soluble form of β-amyloid precursor protein (sAPPα) [7]. The earliest vascular changes observed in psoriasis facilitate the traffic of Th1 lymphocytes subclass in the skin, preserving the psoriatic plaque [3].

Introduction

Inflammatory dermatoses comprise a large spectrum of clinico-morphological entities, the most common, known as major forms of psoriasiform dermatoses, being: psoriasis, pustular psoriasis, Reiter’s syndrome, pityriasis rubra pilaris, lichen simplex chronicus, and large-plaque parapsoriasis (parapsoriasis en grandes plaques). Psoriasis represents the prototype of this category, which can be defined according to inflammation and epidermal changes, the histological mark being regular elongation of rete ridges, due to greater keratinocyte proliferation, partially or totally involving the epidermis [1]. Although the general histological features are shared by most of the inflammatory dermatoses, there are specific microscopical aspects which are pathognomonic for each major form of this disease, which highlight the differences between all inflammatory dermatoses in terms of clinical appearance, pathogenesis and histopathological characteristics related to the quality of scales and the distribution and composition of the inflammatory infiltrate [1].

The aim of our study is to review the main pathogenetic mechanisms and the clinico-histopathological diagnostic features of major form of psoriasiform dermatoses and to emphasize the characteristic microscopical differences between them, for a better approach of the diagnosis, as an important key for clinical and therapeutic management.

Hoe vaak komt actinische keratose voor?

Ongeveer de helft van alle mannen boven 45 jaar en een derde van de vrouwen boven de 45 jaar heeft tenminste één actinische keratose. Dat komt neer op ongeveer 1,4 miljoen Nederlanders. Het komt dus erg vaak voor. Dit komt onder andere door veranderende vrijetijdsbesteding, zonnebanken en zonvakanties. Actinische keratose komt vaker voor bij mensen met een blank huidtype (blond haar en blauwe ogen).

Ongeveer 10% van de patiënten met actinische keratosen ontwikkelt een huidkanker, meestal het plaveiselcelcarcinoom. De kans dat iemand een plaveiselcelcarcinoom krijgt is afhankelijk van de hoeveelheid actinische keratosen. Dit is ongeveer 1% als iemand minder dan vijf actinische keratosen heeft, tot 20% als iemand meer dan twintig actinische keratosen heeft.