Senile purpura:

Multiple purpuric macules

Idiopathic thrombocytopenic purpura:

Multiple petechiae on the arm

Disseminated intravascular coagulation:

Extensive geographic cutaneous infarction on the forearm

Disseminated intravascular coagulation:

Extensive deep purple ecchymoses with

hemorragic blister formation

Henoch-Schonlein purpura:

Multiple palpable deep purple macules on the extensor side of lower extremities and buttocks

Henoch-Schonlein purpura:

Small venules show fibrinoid necrosis with considerable red cell extravasation.

Henoch-Schonlein purpura:

The DIF of IgA shows granular depositions at the papillary dermis.

Pityriasis lichenoides et varioliformis acuta :

Multiple erythematous papules on the back and buttocks

Pityriasis lichenoides et varioliformis acuta :

Multiple erythematous papules with necrotic and crusted lesions on the buttocks

Pityriasis lichenoides et varioliformis acuta :

Multiple erythematous papules with necrotic and crusted lesions on the buttocks

Pityriasis lichenoides et varioliformis acuta :

This view shows basal cell hydropic degeneration, moderate lymphohistiocytic infiltrate at the upper dermis and red cell extravasation.

Pityriasis lichenoides et varioliformis acuta :

This view shows mild spongiosis, basal cell hydropic degeneration, moderate lymphohistiocytic infiltrate at the upper dermis and red cell extravasation.

Pityriasis lichenoides chronica :

Multiple brownish-to-red scaly papules with and crusted lesions

Erythema elevatum diutinum :

Multiple erythematous nodules present on the back of the hand.

Erythema elevatum diutinum :

Multiple erythematous nodules present on the back of the hand.

Erythema elevatum diutinum :

Multiple erythematous nodules present on the palm and fingers.

Erythema elevatum diutinum :

Multiple erythematous nodules present on the palm and fingers.

Sweet’s syndrome :

Erythematous, edematous plaques on the periorbital area with superficial tiny pustules .

Sweet’s syndrome :

Erythematous, edematous plaques on the neck with pustules and crusted lesions .

Sweet’s syndrome :

The epidermis shows subcorneal pustulation. There are diffuse mixed cell infiltrates in the dermis.

Sweet’s syndrome :

The infiltrate consisted largely of neutrophils.

Polyarteritis nodosa:

Several dermal and subcutaneous nodules on the back of the foot.

Polyarteritis nodosa:

Several erythematous dermal and subcutaneous nodules with ulceration on the foot.

Polyarteritis nodosa:

Necrotizing vasculitis is seen within the subcutaneous fat.

Polyarteritis nodosa:

Necrotizing vasculitis is seen within the subcutaneous fat.

Wegener’s granulomatosis:

Several erythematous-dark red ulcerating plaques and nodules on the foot.

Wegener’s granulomatosis:

One erythematous-dark red ulcerating plaque with blister formation.

Wegener’s granulomatosis:

Extensive necrotizing vasculitis is seen within the dermis with red cell extravasation.

Wegener’s granulomatosis:

Close-up view shows necrotizing vasculitis with red cell extravasation.

Wegener’s granulomatosis:

Nasal mucosa biopsy shows necrotizing vasculitis

Wegener’s granulomatosis:

Transbronchial biopsy shows necrotizing vasculitis with extravascular granuloma formation.

Wegener’s granulomatosis:

Chest films shows cavitation on the right upper lobs.

Dego’s syndrome:

Small white papules with central depression and white fine scaling.

Dego’s syndrome:

There is hyperkeratosis with epidermal atrophy

Dego’s syndrome:

There is hyperkeratosis with epidermal atrophy with ectatic vessels.

Dego’s syndrome:

There is hyperkeratosis with epidermal atrophy. Note the ectatic vessels.

Livedo reticularis:

A mottled violaceous discoloration of the skin in a net-like pattern.

Livedo reticularis:

A mottled erythematous discoloration of the skin in a net-like pattern.

Livedoid vasculitis: Multiple purpuric macules

Livedoid vasculitis: Multiple purpuric macules

Livedoid vasculitis: Punched-out ulcers are seen on the ankle

Lymphomatoid granulomatosis: Multiple erythematous macules

Lymphomatoid granulomatosis: Nodular to ulcerative cutaneous lesions

Lymphomatoid granulomatosis: Nodular to ulcerative cutaneous lesions

Lymphomatoid granulomatosis: Nodular lymphoid and/or granulomatous infiltration surrounding the vessels

Lymphomatoid granulomatosis: Nodular lymphoid infiltration surrounding the vessles

Purpura pigmentosa chronica: Multiple erythematous patches on the lower leg

Purpura pigmentosa chronica: Scaly petechial or purpuric macules

Acne vulgaris: Multiple erythematous papules and pustules

Acne vulgaris: Multiple erythematous papules and pustules

Steroid acne: Multiple erythematous papules and pustules

Steroid acne: Multiple erythematous papules and pustules

Neonatal: Multiple erythematous papules and pustules on a neonate

Rosacea: Swollen nose with sebaceous gland hyperplasia and fibrosis

Rosacea: Telangiectasia and erythema.

Androgenic alopecia: Alopecia with the typical M-shape pattern

Follicular muconosis: Acute form. Boggy plaques on the face.

Follicular muconosis: Acute form. Boggy plaques on the face.

Follicular muconosis: Mucin deposition in the follicles. Interfollicular cell infiltrate

Follicular muconosis: Mucin deposition in the follicles. Interfollicular cell infiltrate

Follicular muconosis: Mucin deposition in the follicles. Interfollicular cell infiltrate

Relapsing polychondritis: Erythema, swelling, and pain of the cartilaginous portion of the ear

Relapsing polychondritis: Loss of basophilic staining and breakdown of lacunar structure of the cartilage

Relapsing polychondritis: Loss of basophilic staining and breakdown of lacunar structure of the cartilage

Relapsing polychondritis: Breakdown of lacunar structure of the cartilage

Eosinophilic pustular folliculitis: Erythematous plaque with superimposed coalescent pustules

Eosinophilic pustular folliculitis: Erythematous plaque with superimposed coalescent pustules

Eosinophilic pustular folliculitis: Microabscess composed of eosinophils

Pityrosporum folliculitis: Pruritic eryhematous papules and pustules, primarily on the back, chest, and shoulders

Pityrosporum folliculitis: Pruritic eryhematous papules and pustules, primarily on the back, chest, and shoulders

Eosinophilic cellulitis: Recurrent painful or pruiritic plaques

Eosinophilic cellulitis: Recurrent painful or pruiritic plaques with bullae

Eosinophilic cellulitis: Recurrent painful or pruiritic plaques with bullae

Eosinophilic cellulitis: Diffuse eosinophilic infiltrate throughout the dermis

Eosinophilic cellulitis: Diffuse eosinophilic infiltrate throughout the dermis. Flame figures can be seen.