Differential Diagnosis in Dermatopathology

Acne vulgaris, erythematous papule vs. Rosacea, erythematous papule

Infection of skin and subcutaneous tissue by atypical mycobacteria, that is, mycobacteria other than those responsible for tuberculosis and leprosy, expressed clinically as keratotic and crusted papules, plaques, nodules, and tumors that may be punc…

Histologic Diagnosis of Inflammatory Skin Diseases

Rosacea

Rosacea Synonyms Gutta rosea Presentation stereotypical Age and sex Young and middle-aged adults, usually Caucasian women Distribution of lesions Center of the face in vertical and horizontal directions, i.e., nose, forehead, cheeks, and chin Indivi…

Histologic Diagnosis of Inflammatory Skin Diseases

Images

Images 10.94.1A: Infundibulitis, spongiotic, and peri-infundibulitis, granulomatous + 10.94.1B: Lymphocytes and plasma cells around collections of epithelioid histiocytes = Rosacea, papular ┬áSpongiosis in an infundibulum is a finding comm…

Histologic Diagnosis of Inflammatory Skin Diseases

Arthropod assaults

Arthropod assaults Synonyms Insect “bite” Bug bite Insect bite reaction Papular urticaria Lichen urticatus Strophulus Presentation stereotypical Age and sex Any age and both sexes Distribution of lesions At times only a single lesion a…

Histologic Diagnosis of Inflammatory Skin Diseases

Collagen

More than 70% of the dry weight of the normal dermis consists of collagen (Fig. 1.79). The major collagens are Type I and Type III. Type I collagen has a molecular mass of about 290 KDa and accounts for approximately 80% of the total amount of colla…

Histologic Diagnosis of Inflammatory Skin Diseases

Our Definition of “Inflammation” and “Inflammatory Disease”

What follow now are our definitions of the terms inflammation and inflammatory disease as we employ them in this volume. Inflammation. Changes in tissue that occur typically as a reaction to injury of any kind (e.g., mechanical, actinic, chemical,…

Histologic Diagnosis of Inflammatory Skin Diseases

Images

Images 10.8.1A: Perivascular and interstitial dermatitis + 10.8.1B: Large numbers of neutrophils scattered interstitially in association with degeneration of collagen = Beh├žet’s disease Dense infiltrates of neutrophils in the dermis…

Dermatology Practical & Conceptual

Multiple confluent reddish nodules

The patient A 48-year-old fisherman from Amazonas (north of Brazil) developed a small papule on the anterior left leg after a traumatic injury with a piece of wood 20 years ago. Over the course of years, multiple large, confluent, reddish to brownis…

Differential Diagnosis in Dermatopathology

Discussions

Erythema nodosum and nodular vasculitis are stereotypes of septal and lobular panniculitis, respectively. When developed fully, erythema nodosum is a granulomatous and fibrosing septal panniculitis and nodular vasculitis is a necrotizing, suppurativ…

Histologic Diagnosis of Inflammatory Skin Diseases

Deep fungal infections

Deep fungal infections Synonyms Mycetoma Subcutaneous mycoses Dermal mycoses Presentation stereotypical Age and sex Any age, both sexes Distribution of lesions Localized or widespread; some infections favor exposed sites; internal organs sometimes…