logo Inflammatory reactions

Systemic dermatology

Inflammatory reactions


  • Recognise inflammatory reactions to systemic disease.


Panniculitis is the term used for a group of disorders in which inflammation primarily affects subcutaneous tissue.

Erythema nodosum

Erythema nodosum

Erythema multiforme

Erythema multiforme (EM) is an acute eruption of erythematous target or iris-shaped plaques that may blister, typically involving the extremities (face, palms, soles and distal limbs).

EM minor

Erythema multiforme minor

EM major

Erythema multiforme major (Steven’s Johnson syndrome)

Toxic epidermal necrolysis

Toxic epidermal necrolysis

Annular erythemas

Several patterns of annular erythema are described, sometimes specific to the underlying aetiology.

Erythema annulare centrifugum results in expanding erythematous annular and polycyclic plaques, generally on the trunk.

Annular erythema

Erythema gyratum repens in patient with metastatic gastric cancer

Typical trailing scale in chronic annular erythema

Neutrophilic dermatoses

Dermatoses with dense dermal infiltrates of neutrophils include:

Pyoderma gangrenosum is associated with inflammatory bowel disease, rheumatoid arthritis and haematological malignancies but occasionally arises in otherwise healthy individuals. Sweet’s can have similar causes but more often follows an upper respiratory tract infection

Pyoderma gangrenosum results in severe ulceration characterised by an overhanging necrotic edge and severe pain. It most commonly arises on the lower legs and may be very difficult to control requiring one or more systemic immune suppressive medications.

Bullous PG

Ulcerated PG

Sweet’s disease presents as rapidly evolving juicy “pseudo-vesicular” plaques accompanied by fever, leukocytosis, conjunctivitis and arthralgia. The lesions are most often located asymmetrically on the upper extremities, neck and face. They heal within two or three months without scarring, but resolve very quickly if treated with oral prednisone for 4 to 6 weeks.

Sweet’s disease

Resolving Sweet’s disease

Pustular vasculitis (variant neutrophilic dermatosis)