Dr  Sampurna Roy  MD

 The term 'Inflammatory skin disease' is used to described all non-neoplastic conditions.

-A detailed clinical history should be obtained from the clinician which should include age, patient, sex, personal and family history of skin disease, drug history, allergies, type and distribution of rash.

-Biopsy should be taken from the edge of the lesion. The specimen should include normal tissue and should be deep enough to include subcutaneous adipose tissue.  (Gross examination of the skin specimen)

- A systematic analysis of the biopsy is necessary starting form keratin layer, epidermis, dermo-epidermal junction, the superficial and deep dermis, the fat and finally the blood vessels.  (Normal Histology of Skin)

- Decide on the major patterns of involvement . The inflammatory skin disease is classified according to the type of tissue reaction and nature and distribution of the inflammatory infiltrate.

Types of Tissue Reaction:

Lichenoid (Interface)Tissue Reaction Pattern

Psoriasiform Reaction Pattern

Granulomatous Reaction Pattern

Vesiculobullous Reaction Pattern

Spongiform Reaction Pattern

Vasculopathic Reaction Pattern

Nature of inflammatory Infiltrate:

NEUTROPHILS - Abscess/folliculitis ; Vasculitis ; Superficial dermatophyte inf.
Psoriasis ;  Dermatitis herpetiformis ; Granuloma faciale ; Sweet's syndrome; Erythema elevatum diutinum.

LYMPHOCYTE -  Lupus erythematosus ; Lichen planus ; Erythema multiforme;
Lichen simplex chronicus ; Stasis dermatitis ; Pigmented purpura ; Viral exanthema ; Graft versus host disease ; Polymorphous light eruption
Jessner's lymphocytic eruption ; Lymphoma.

EOSINOPHILS -  Drug/allergic reaction ;  Insect bite reaction ;  Bullous pemphigoid ; Superficial dermatophyte infection ; Granuloma faciale ;
Well's syndrome.

MIXED INFILTRATE - Urticarial reactions ; Dermatophyte infection ; Insect bites ; Sweet's syndrome ; Granuloma faciale.

MAST CELLS - Urticaria pigmentosa ; Telangiectasia macularis eruptiva.

PLASMA CELLS -   Syphilis ;   Lyme disease;   Zoon's balanitis ;   Necrobiosis  lipoidica.

CELL POOR -  Porphyria/pseudoporphyria ; Cell poor bullous pemphigoid ; Cutaneous amyloidosis ;  Mucinosis.

When biopsy looks relatively normal:
-Levels are performed as pathological features may be  present in deeper level.
-Special stains may be required in case of certain "invisible dermatosis".

Examples of invisible dermatosis:                

Toluidene Blue    -      Urticaria  pigmentosa
Elastic                 -      Pseudoxanthoma elasticum
PAS                     -      Dermatophyte infection
Sirius red:            -      Macular amyloidosis             
Perl's                   -      Pigmented pupura
Alcian blue         -      Mucinoses

Invisible dermatoses with subtle, but diagnostic abnormalities on H&E stain:

 - Granuloma annulare (interstitial form)
 - Urticarial reactions
 - Exanthematous viral and drug reactions
 - Morphea

Bullous lesions require immunofluorescence for confirmation of diagnosis.

Immunofluorescence plays an important role in the investigation of  inflammatory skin disease specially in vesiculo-bullous disorders.

                   
Report should comment on the following features:         (Glossary)

 I EPIDERMIS : 

Hyperkeratosis ; parakeratosis ; hypergranulosis ; spongiosis & spongiotic vesicles ; acantholysis  ;  papillomatosis  ; acanthosis (irregular, saw-tooth or psoriasiform) ; atrophy ; intraepidermal bulla ;  inflammatory cellular infiltrate ; presence of viral inclusion ; Civatte body ; erosions and ulceration.

II DERMOEPIDERMAL JUNCTION :  

Subepidermal bulla formation (with eosinophils , neutrophils or little or no inflammatory infiltrate) ; vacuolar degeneration; an inflammatory infiltrate (band-like, patchy, plasma cells) ; basement membrane thickening.

III DERMIS:  

Solar elastosis:

Change in collagen pattern:   (presence of edema fluid ;  edema fluid and eosinophils ;  edema fluid & mast cells  ;  thickening of bundles ; dense superficial bands of collagen ; thickening and obliteration of fibres; deep extension and entrapment of sweat glands and subcutaneous adipose tissue ;  hyalinization with swirling pattern ; deposition of mucin ;  presence of flame figures ; destruction of collagen. )

Inflammatory infiltrate:  Type :   Neutrophilic ; Mast cells ; Lymphocytic ; Lymphoplasmacytic ; follicular ; granulomatous ; histiocytic.

Distribution:    Band-like ; V-shaped ; Perivascular inflammation ( superficial or superficial & deep) ; Neutrophils around hair follicles ; Mononuclear inflammatory infiltrate around nerves.

Primary Vasculitis:  ( Arterial ; arteriolar ; capillary ; venous  )

Abnormalities of hair follicle.

Microbes ( special stains are often used to demonstrate organisms ).

IV SUBCUTIS

Septal panniculitis or lobular panniculits / presence of calcification / vasculitis/ extension of reticular dermis .