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Inflammatory Dermatoses –Think Like a Clinician

Dirk M. Elston, MD

Medical University of South Carolina

Charleston

Think like a Clinician

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• “If it scales scrape it.” = “If it scales and you don’t know what it is, PAS it.”

Think like a Clinician

• Try to picture the clinical lesion based on the histologic findings

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Normal baketweave corneum = acute process

Compact corneum = chronic process

What is the timing of this lesion?

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Upper corneum normal, lower compact = 1 - 2 weeks duration

What is the timing of this lesion?

Alternating basketweave and compact parakeratotic corneum = intermittent

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Thick irregular corneum and acanthosis/papillomatosis =

verrucous lesion

Parakeratosis = scale

Exception: Furfuraceous scale

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Spongiosis = eczema

Spongiosis = eczema

Spongiotic conditions usually = pink in white skin,

hypopigmented in dark skin

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Vacuolar interface = pink

Lichenoid interface usually = violaceous

Interface + melanoderma = marked hyperpigmentation or

mottled hyper/hypopigmentation

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Serum = crusting

PEH = epithelial hyperplasia clinically

Papillary dermal fibrosis = chronicity

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Watch out for clinical names

• Names are often “misnomers”– Mycosis fungoides

– Granuloma faciale

– Eosinophilic fasciitis

A Lymph in Every Hole

• MF

• PLEVA

• PLC

• BLK

• MF-like histology in BLK

• Fixed drug

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PLCEach lesion is acute

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PLEVAPLEVA

PLEVA

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What is the timing this lesion?

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SCLE

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Lymphs in the Eccrine Coil

• Lupus

• Lymphoma

• Lichen Striatus

Lymphs in the Eccrine Coil

• PMLE

• Unilateral laterothoracic exanthem

• Jessner's

• GVHD

• Pernio

• Arthropod reaction

• Lymphocytic eccrine hidradenitis

• Aicardi-Goutieres Syndrome

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Dermatomyositis:Looks like LEMay be atrophic or lichenoid

DM vs. LE

• Pruritus

• Knuckles (vs. interphalangeal)

• Heliotrope

• Shawl

• Extensors

• Nail folds: dilatation and dropout (vs. glomeruloid loops)

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Perniosis, Acute PMLE

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Syphilis

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Take-Home Points

• Specimens with ≤5 features more likely to– be from the trunk (61.1% of cases with ≤5

features vs 34.4% overall)

– demonstrate rete ridge effacement (44.8% vs 19.8%)

– have pityriasis rosea (33.3% vs 17.2%) or drug eruption (33.3% vs 10.9%) in the clinical differential

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Take-Home Points

• An interstitial inflammatory pattern was the most common characteristic of specimens with ≤5 features (present in 75.9%).

• Cases with only two diagnostic features demonstrated an interstitial pattern with either endothelial swelling or lymphocytes with ample cytoplasm.

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Fixed drug eruption

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GVHD

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Nodular and Diffuse Dermatoses

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Sweet’s syndrome

Massive papillary dermal edemaNodular and diffuse neutrophilic infiltrateKarryorrhexis

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Sandfly

Leishmaniasis

Nodular and diffuse infiltrate of histiocytesand plasma cells

Intracellulare organismsPeriphery of vacuole

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Leprosy

Hansen’s disease

Hansen’s diseasePerivascular and periadnexal histiocyte,granulomas, globi

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Granuloma annulare

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Granuloma annulare

Palisaded or patchy interstitialhistiocytic infiltratewith mucin

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Necrobiosis lipoidica

Necrobiosis lipoidica

Layered granulomaswith pale devitalized collagen

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Rheumatoid nodule:Palisaded granuloma with fibrin

DDX: “Deep” GA

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Sarcoidosis

Sarcoidosis

Nodular non-caseating “naked” granulomas

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Xanthogranulomas

JuvenileAdultNecrobiotic

Xanthogranulomas

JuvenileAdult

Nodular and diffuse histiocytesEpithelioidLanghansTouton

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Xanthogranulomas

Necrobiotic

NodulesXanthogranulomaDevitalized collagenCholesterol cleftsParaproteinemia

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Reticulohistiocytic granuloma

Ground glass two tone cytoplasmRetraction space

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Xanthomas

XanthomasFoamy histiocytesFibrosis -- tuberousExtracellular lipid -- eruptive

Eruptive xanthomas:Diabetes, hypothyroidism

Apoprotein C-II:Type I and some Type V

Apoprotein E-II:Type III

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Tuberous xanthomas

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Tendon Xanthomas

Palmar Crease Xanthomas (Type III)Apoprotein E2

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Normolipemic planar xanthoma:Association with paraproteinemia and myeloma

Rosacea and acne agminata

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Courtesy Larry Gibson, MD

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Rosacea• Patchy perifollicular lymphohistiocytic

• Ectasia

• Fibrosis

Lupus erythematosus

Lupus erythematosusVacuolar or lichenoidinterface dermatitis

Patchy perivascular and periadnexal lymphoid infiltrate

Nodular SQ infiltrate

Lymphoid aggregates in eccrine coil

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Lupus erythematosus

Compact hyperkeratosis

Follicular plugging

BMZ thickening

Dermal mucin

Acute Cutaneous Lupus

• Malar

• Pink

• Non-scarring

• ds-DNA

• Penicillamine

Subacute Cutaneous Lupus

• Trunk, face, extremities

• Pink

• Annular or psoriasiform

• Ro (SSA), La (SSB)

• Neonatal LE

• Thiazide diuretics

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Acral Lupus

• Lichenoid clinically

• Lichenoid histology

• Linear immunoglobulin

• SCC in longstanding lesions

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Morphea:Nodular lymphoid infiltratesPeriadnexal, SQ

Hyalinized collagen

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Lupus destroys elastic fibers

Morphea preserves elastic fibers

Pseduomonas sepsis:Nodular gray aggregatesSurround infarcts

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Cellulitis and necrotizing fasciitisNeutrophilic infiltrate

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Bites/stings

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Mastocytosis

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Pigmenting purpura

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Spongiotic with RBCs in epidermis:Pityriasis roseaPigmenting purpura (Dukas)

Interface with RBCs in epidermisPityriasis lichenoidesPigmenting purpura (Gougerot-Blum)