[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Skin](https://durgical.com/en/general-pathology/areas/skin/) › Skin pathology: terms and reaction patterns

# Skin pathology: terms and reaction patterns

- Topic

Skin is a living barrier with its own immune cells. Pathologists describe its diseases with a small set of words and patterns.

Updated Nov 12, 2026

## Key points

- Hyperkeratosis: thick stratum corneum; parakeratosis: retained nuclei in the stratum corneum (normal on mucosa).
- Acanthosis: thick epidermis; papillomatosis: elongated dermal papillae; dyskeratosis: premature keratinisation of single cells.
- Spongiosis: oedema between keratinocytes (eczema); acantholysis: loss of cell-to-cell adhesion (pemphigus).
- Interface dermatitis: damage of the basal layer with lymphocytes (lichen planus, lupus, erythema multiforme).
- Lentiginous: single melanocytes along the basal layer; exocytosis: inflammatory cells within the epidermis.
- Main patterns: spongiotic, psoriasiform, interface, vesiculobullous, vasculopathic, granulomatous, panniculitis.

## What it is

The skin is the largest organ and a busy immune site. Keratinocytes held together by desmosomes form the barrier and release cytokines; melanocytes give pigment; Langerhans cells and dermal dendritic cells sample antigens; resident memory T cells patrol. Inflammatory skin diseases produce a limited number of reaction patterns, and knowing the vocabulary lets you read any biopsy report.

## Function

- Barrier: keratin, lipids and tight junctions prevent water loss and microbial entry.
- Innate defence: keratinocytes make defensins and cathelicidins and release IL-1, IL-6 and TNF when injured.
- Antigen presentation: Langerhans cells carry antigens to lymph nodes.
- Pigment: melanocytes transfer melanin to keratinocytes to shield nuclei from UV light.
- Vitamin D synthesis and thermoregulation.

## Inflammatory reaction patterns

| Pattern | What is seen | Typical diseases |
| --- | --- | --- |
| [Spongiotic](https://durgical.com/en/conditions/atopic-dermatitis/) | Intercellular oedema, vesicles | Eczematous dermatitis |
| [Psoriasiform](https://durgical.com/en/conditions/psoriasis/) | Regular elongation of rete ridges | Psoriasis, chronic eczema, seborrheic dermatitis |
| [Interface](https://durgical.com/en/conditions/lichen-planus/) | Basal vacuoles, apoptotic keratinocytes, lymphocytes | Lichen planus, erythema multiforme, lupus |
| [Vesiculobullous](https://durgical.com/en/conditions/pemphigus-vulgaris/) | Split at a given level | Pemphigus, pemphigoid, dermatitis herpetiformis |
| [Vasculopathic](https://durgical.com/en/conditions/cutaneous-small-vessel-vasculitis/) | Vessel wall damage | Leukocytoclastic vasculitis |
| [Granulomatous](https://durgical.com/en/conditions/sarcoidosis/) | Epithelioid histiocytes | Sarcoidosis, tuberculosis, leprosy |
| [Panniculitis](https://durgical.com/en/conditions/erythema-nodosum/) | Inflammation in fat | Erythema nodosum |

## Clinical notes

- Clinical words (macule, papule, plaque, vesicle, bulla, pustule, lichenification) pair with these microscopic terms.
- Punch biopsy at the edge of an active lesion gives the most information; blisters need perilesional tissue for immunofluorescence.

## Memory aid

Spongiosis is water between bricks, acantholysis is mortar gone, acanthosis is a taller wall, and interface is a fire at the foundation.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the difference between spongiosis and acantholysis?

Spongiosis is intercellular oedema stretching intact desmosomes; acantholysis is loss of cohesion between keratinocytes from broken desmosomes.

## What is parakeratosis?

Retention of nuclei in the stratum corneum, a sign of rapid or abnormal keratinisation (normal only on mucosa).

## Which two diseases show an interface pattern?

Lichen planus and erythema multiforme (also lupus erythematosus).

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/skin-pathology-terms-and-reaction-patterns/)

[More Pathology questions →](https://durgical.com/en/practice/?f=pathology)

## Elsewhere in DurgiPedia

- [Skin: epidermis layers, dermis, hypodermis](https://durgical.com/en/histology/skin-epidermis-layers-dermis-hypodermis/)
- [Keratinocytes, melanocytes, Langerhans and Merkel cells](https://durgical.com/en/histology/keratinocytes-melanocytes-langerhans-and-merkel-cells/)
- [Hair follicles, sebaceous and sweat glands, nails](https://durgical.com/en/histology/hair-follicles-sebaceous-and-sweat-glands-nails/)
- [Skin examination: primary and secondary lesions](https://durgical.com/en/clinical-exam/skin-examination-primary-and-secondary-lesions/)
- [Dendritic cell (professional antigen-presenting cell)](https://durgical.com/en/immunology/dendritic-cell/)

## Connections

## Related 5

- [Eczematous dermatitis](https://durgical.com/en/general-pathology/eczematous-dermatitis/)
- [Psoriasis and seborrheic dermatitis](https://durgical.com/en/general-pathology/psoriasis-and-seborrheic-dermatitis/)
- [Lichen planus and interface dermatitis](https://durgical.com/en/general-pathology/lichen-planus-and-interface-dermatitis/)
- [Pemphigus](https://durgical.com/en/general-pathology/pemphigus/)
- [Panniculitis](https://durgical.com/en/general-pathology/panniculitis/)

## Related conditions 7

- [Atopic dermatitis](https://durgical.com/en/conditions/atopic-dermatitis/)
- [Psoriasis](https://durgical.com/en/conditions/psoriasis/)
- [Lichen planus](https://durgical.com/en/conditions/lichen-planus/)
- [Pemphigus vulgaris](https://durgical.com/en/conditions/pemphigus-vulgaris/)
- [Bullous pemphigoid](https://durgical.com/en/conditions/bullous-pemphigoid/)
- [Erythema nodosum](https://durgical.com/en/conditions/erythema-nodosum/)
- [Contact dermatitis (irritant and allergic)](https://durgical.com/en/conditions/contact-dermatitis/)

[← All of general pathology](https://durgical.com/en/general-pathology/)

Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Skin Conditions](https://medlineplus.gov/skinconditions.html) (MedlinePlus, US National Library of Medicine, 2025).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/general-pathology/skin-pathology-terms-and-reaction-patterns/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/skin-pathology-terms-and-reaction-patterns/