From the Guidelines
Parakeratosis, hyperkeratosis, and acanthosis are distinct histological terms that describe abnormal skin changes, with parakeratosis referring to the abnormal retention of nuclei in the stratum corneum, hyperkeratosis describing an abnormal thickening of the stratum corneum, and acanthosis referring to thickening of the epidermis, specifically the stratum spinosum layer. These terms are essential in dermatology, as they help diagnose specific skin conditions by examining tissue samples under a microscope 1. The provided evidence from the British Association of Dermatologists' guidelines for the care of patients with actinic keratosis 2017, although focused on actinic keratosis, highlights the importance of understanding these histological terms in the context of skin disorders 1. Some key points about these terms include:
- Parakeratosis indicates disrupted skin cell differentiation and is commonly seen in conditions like psoriasis
- Hyperkeratosis can occur from increased cell production or delayed shedding of skin cells and is present in conditions such as calluses, warts, and eczema
- Acanthosis appears as elongation of the rete ridges and is characteristic of conditions like acanthosis nigricans and psoriasis Understanding these terms is crucial for accurate diagnosis and appropriate treatment of dermatological conditions, as they often coexist in various skin disorders 1.
From the Research
Definitions of Key Terms
- Parakeratosis: a mode of keratinization characterized by the presence of nuclei in the stratum corneum, which is the outermost layer of the epidermis 2, 3. It is often associated with granular parakeratosis, a rare skin condition that presents as erythematous to brown hyperkeratotic papules.
- Hyperkeratosis: a thickening of the stratum corneum, often resulting in a rough, scaly texture 2, 4, 5. It can be a feature of various skin conditions, including granular parakeratosis and epidermolytic acanthoma.
- Acanthosis: a thickening of the epidermis, particularly the stratum spinosum, which is the layer of cells below the stratum corneum 4, 6. It can be a feature of various skin conditions, including epidermolytic acanthoma and atypical melanocytic lesions.
Characteristics of Related Skin Conditions
- Granular Parakeratosis: a rare, idiopathic, and benign skin condition that presents classically as erythematous to brown hyperkeratotic papules that can coalesce into plaques 2, 3.
- Epidermolytic Acanthoma: an uncommon cutaneous entity that typically presents as a solitary lesion, or, less commonly, as multiple or disseminated discrete lesions, with histopathological features of epidermolytic hyperkeratosis and acanthosis 4.
- Hyperkeratotic Flexural Erythema: a scaly, erythematous or brown eruption, which usually occurs in the intertriginous and flexural areas, and has been linked to the use of benzalkonium chloride 5.