Inflammatory Dermatopathology: A Survival Kit for Surgical Pathologists Steven D. Billings, MD Cleveland Clinic, Cleveland, OH [email protected] Inflammatory Dermatopathology • Difficult • Overlapping histologic features • Impenetrable terminology • Specific diagnosis often elusive Inflammatory Dermatopathology How to produce good reports • Diagnostic category • Tumor vs. rash? • Which inflammatory pattern? • Clinical presentation • Information regarding clinical features can influence histologic interpretation • Communication with clinicians crucial • Telephone 2nd most important tool 1 Ideal Dermatopathology Report • Microscopic description • Diagnosis • Specific diagnosis often not possible • Often ―descriptive‖ diagnosis • Example: ―Spongiotic dermatitis‖ • Note • Explain differential diagnosis • What diagnosis is favored • Additional comments as needed Pattern Recognition • Skin has limited ways to react • Predominant pattern of inflammatory infiltrate helps define diagnostic categories • Patterns can overlap • Some entities can have a variety of patterns General Concepts • Pattern recognition • Epidermal predominant vs. dermal predominant • Epidermal changes trump dermal changes • Distribution of the inflammatory infiltrate • Superficial vs. superficial and deep • Location: perivascular, interstitial, nodular • Nature of inflammatory infiltrate • Mononuclear (lymphocytes and histiocytes) • Mixed (mononuclear and granulocytes) • Granulocytic • Correlation with clinical presentation 2 Principle Patterns: Epidermal Changes Predominant • Spongiotic pattern • Psoriasiform pattern • Spongiotic and psoriasiform often co-exist • Interface pattern • Basal vacuolization • Perivascular infiltrate or • Lichenoid infiltrate Principle Patterns: Dermal Changes Predominant • Superficial perivascular • Superficial and deep perivascular • Interstitial pattern • Palisading granulomatous • Nodular and diffuse • Sclerosing pattern • Panniculitis • Bullous disease • Miscellaneous Spongiotic Dermatitis 3 Case A 40-year-old woman presented with linear blisters on both forearms. 4 Diagnosis: Spongiotic Dermatitis 5 Spongiotic Dermatitis • Three phases • Acute • Subacute • Chronic • Different but overlapping histologic features Spongiotic Dermatitis • Acute spongiotic dermatitis • Normal ―basket-weave‖ stratum corneum • Pale keratinocytes • Spongiosis • Spongiotic vesicles (variable) • Papillary dermal edema • Variable superficial perivascular infiltrate of lymphocytes often with some eosinophils 6 Spongiotic Dermatitis • Subacute spongiotic dermatitis • Parakeratosis • Diminished granular layer • Spongiosis • Acanthosis (overlap with psoriasiform pattern) • Variable superficial perivascular infiltrate of lymphocytes often with some eosinophils • Less edema 7 Spongiotic Dermatitis • Chronic spongiotic dermatitis • Hyperkeratosis • Parakeratosis • Irregular granular layer • Acanthosis (overlap with psoriasiform) • Minimal to mild spongiosis • Variable perivascular infiltrate • Dermis may be fibrotic 8 Common Clinical Types of Spongiotic Dermatitis • Eczema Dermatitis Family • Atopic dermatitis • Contact dermatitis • Nummular dermatitis • Dyshidrotic dermatitis (hand/foot dermatitis) • Id reaction (autoeczematization) • Eczematous drug eruption Eczema • Clinical term • Histologically spongiotic dermatitis • Specific diagnosis dependent on correlation with clinical presentation • CLINICAL SUBTYPES ARE HISTOLOGICALLY INDISTINGUISHABLE Atopic Dermatitis • Chronic pruritic, relapsing papular dermatitis • Associated with history of asthma, allergic rhinitis (atopy) • Predilection for flexural areas, especially in children 9 Allergic Contact Dermatitis • Clinical • Erythematous papules, plaques and sometimes vesicles • May have linear pattern • Secondary to type IV delayed hypersensitivity reaction • Examples: nickel allergy, poison ivy • Microscopic • Typical spongiotic dermatitis • May have Langerhans cell microabscesses 10 11 Irritant Contact Dermatitis • Clinical • Erythematous papules and vesicles • Secondary to direct irritant effect • Example: diaper rash • Microscopic • Typical spongiotic dermatitis • Ballooning degeneration of keratinocytes Nummular Dermatitis • Common form of eczema that is biopsied • Clinical • Pruritic round to oval patches and plaques • Often on extremities • Microscopic • Psoriasiform and spongiotic • Can be classified as psoriasiform dermatitis • Differential diagnosis • Psoriasis 12 Dyshidrotic Eczema (Pomphylox) Symmetric involvement of hands and/or feet Often vesicular Clinical and histologic differential diagnosis: vesicular dermatophyte infection 13 Id Reaction (Autoeczematization) • Widespread dissemination of previously localized ―eczematous‖ process • Triggers • Dermatophyte infection • Stasis dermatitis • Discontinuation of systemic steroids • Others • Abnormal immune response to skin antigens 14 Eczematous Drug Reaction Clinical • 5-10% of drug reactions may be eczematous in nature • Widespread eruption • Microscopic • Typical spongiotic dermatitis Practical Tips for Eczematous Dermatitis • Dx: ―spongiotic dermatitis, see note‖ • Dx in cases with acanthosis: ―spongiotic psoriasiform dermatitis, see note‖ • Note: ―The histologic features are compatible with an eczematous dermatitis. The DDx could include….. Clinicopathologic correlation is recommended.‖ • Tips • Eliminate where possible more specific entities • Neutrophils in stratum corneum or epidermis: exclude dermatophytosis or psoriasis • Clinical history can be helpful • Langerhans cell microabscess: suggest contact dermatitis Other Forms of Spongiotic Dermatitis • Vesicular dermatophytosis • Stasis dermatitis • Pityriasis rosea 15 Case 68 year-old woman with crusted, red scaly plaques on lower legs 16 Stasis Dermatitis • Clinical • Lower extremities associated with venous insufficiency • May develop ulcers • May clinically mimic a neoplasm (e.g. SCC) • Microscopic • Subacute to chronic spongiotic dermatitis • Significant acanthosis • Lobular proliferation of thick-walled dermal vessels • Extravasated erythrocytes, siderophages, perivascular lymphocytes • Variable dermal fibrosis 17 Stasis Dermatitis • Differential diagnosis • Eczematous dermatitis • Kaposi sarcoma • Tips • High index of suspicion • Vascular changes key feature 18 Case 29 year-old medical student with red scaly plaques on trunk 19 Pityriasis Rosea • Clinical • Affects young adults • Round to oval salmon-colored herald patch • Widespread, symmetric eruption on trunk . Microscopic • Subacute spongiotic dermatitis • Mounds of parakeratosis • Superficial perivascular mononuclear cell infiltrate • Extravasation of erythrocytes in papillary dermis 20 Pityriasis Rosea • Differential diagnosis • Eczematous dermatitis, guttate psoriasis • Tips: • Parakeratotic mounds key feature • Sign out descriptively in absence of good history • Dx: Spongiotic dermatitis • Note: Given the discrete mounds of parakeratosis, the histologic differential diagnosis would include pityriasis rosea. CPC recommended. Psoriasiform Dermatitis • Pattern often co-exists with spongiosis • Entities in psoriasiform dermatitis ddx • Psoriasis • Subacute to chronic spongiotic dermatitis • Stasis dermatitis • Lichen simplex chronicus/prurigo nodularis • Dermatophytosis • Pityriasis rubra pilaris Psoriasiform Dermatitis 21 Case A 35-year-old man presented with large plaques on his elbows and trunk. 22 23 Psoriasis Psoriasis vulgaris • Clinical • Usually presents in 2nd-3rd decades • Erythematous plaques with silvery scale • Extensor surfaces, scalp, gluteal cleft, glans penis • Nail pitting and yellow discoloration • Arthritis 1-5% Psoriasis Vulgaris • Microscopic • Uniform acanthosis with elongated rete ridges • Absent (diminished) granular layer • Prominent parakeratosis • Neutrophils in stratum corneum (Munro‘s microabscess) and/or epidermis (pustules of Kogoj) • Suprapapillary plate thinning • Dilated, tortuous papillary dermal vessels 24 Psoriasis Vulgaris • Differential Diagnosis • Nummular dermatitis • Contact dermatitis • Seborrheic dermatitis • Pityriasis rubra pilaris • Dermatophytosis Psoriasis Vulgaris • Practical tips • Eosinophils absent in psoriasis (intravascular eosinophils don‘t count) with one exception • Epidermal hyperplasia not always uniform • Impetiginization not seen • May see some granular layer in rubbed psoriasis • Some features may be absent in partially treated psoriasis • Descriptive dx: psoriasiform dermatitis 25 Psoriasis Variants Pustular psoriasis • Clinical • Associated with pregnancy and discontinuation of systemic steroids • Rapid onset • Microscopic • Epidermal hyperplasia rare • Granular layer diminished but not absent • Large neutrophilic abscesses in epidermis and stratum corneum • Little spongiosis • Differential Diagnosis • candidiasis, eczematous dermatitis with secondary impetiginization, acute generalized exanthematous pustulosis (AGEP), IgA pemphigus http://www.internationaleczema-psoriasisfoundation.org 26 Psoriasis Variants Guttate psoriasis • Clinical • Rapid onset • Widespread disease • Small scaly plaques • Antecedent streptococcal infection 27 Psoriasis Guttate psoriasis • Microscopic • Minimal acanthosis • Diminished granular layer (variable) • Focal mounds of parakeratosis with neutrophils • Differential Diagnosis • Pityriasis rosea TNF-α Inhibitor-induced psoriasis • TNF-α inhibitors • Examples: infliximab, adalimumab, certolizumab • Used to treat inflammatory bowel disease, rheumatoid arthritis, psoriasis • Can induce psoriasis • Histologically resembles psoriasis vulgaris,