Resolving Quandaries in Dermatology, Pathology & Dermatopathology

Mucha-Habermann Disease a Lymphocytic Vasculitis?

“The basic and essential histopathologic change in pityriasis lichenoides et varioliformis acuta is a vasculitis, differing from pityriasis lichenoides chronica, which is primarily a disease of the epidermis…Very important and never des…

Histologic Diagnosis of Inflammatory Skin Diseases

Leukocytoclastic vasculitis

Leukocytoclastic vasculitis Synonyms Leukocytoclastic angiitis Allergic vasculitis Hypersensitivity angiitis Hypersensitivity vasculitis Anaphylactoid purpura Immune complex vasculitis Purpura rheumatica Presentation stereotypical Age and sex Any ag…

Differential Diagnosis in Dermatopathology

Subcutaneous granuloma annulare vs. Rheumatoid nodule

A type of small-vessel vasculitis (venulitis) of the skin, occurring especially in the vicinity of the ankle, characterized at first by purpuric macules and patches that, in time, may become hemorrhagic blisters that ulcerate and heal with white, st…

Histologic Diagnosis of Inflammatory Skin Diseases

Identification of Basic Patterns: Skin: Perivascular Dermatitis

…distinctive sign of injury from outside the skin (scratching): fibrin beneath the epidermis. Fibrin situated immediately beneath the epidermis is a sure sign that the trauma responsible was delivered from outside the skin. Figure 5.170 A&B. A…

Histologic Diagnosis of Inflammatory Skin Diseases

Confusing Terms (to be Avoided Scrupulously)

APOPTOSIS [Gk. apo- (away from) + ptosis (a falling)]: Reputed to be a specific type of cell death in which dead cells are said to undergo fragmentation by implosion with subsequent phagocytosis of nuclear debris (Fig. 3.40). The process is claimed…

Resolving Quandaries in Dermatology, Pathology & Dermatopathology

Atrophie Blanche?

…f a vasculopathy in which occlusion of small dermal vessels by fibrin thrombi is the primary event. It appears to result from described fibrinolytic activity of the blood with defective release of tissue plasminogen activator from vessel walls.&#8221…

Histologic Diagnosis of Inflammatory Skin Diseases

Septic vasculitis

…sculitis is devoid of it; leukocytoclastic vasculitis exhibits fibrin within the wall of venules and no thrombi in the lumen of them, whereas in septic vasculitis, fibrin is not found in the wall of vessels, but thrombi are present in some lumen, and…

Histologic Diagnosis of Inflammatory Skin Diseases

Images

Images 10.19.1A: Perivascular and interstitial dermatitis + 10.19.1B: Neutrophils and nuclear “dust” at the tip of edematous dermal papillae, obscuration of the junction by inflammatory cells, and hints of subepidermal fibrin

Histologic Diagnosis of Inflammatory Skin Diseases

Granuloma annulare

Granuloma annulare Presentation stereotypical Age and sex Any age in both sexes Distribution of lesions Localized, often to extensor aspects of extremities, or widespread Configuration of lesions Annular, sometimes arcuate Arrangement of lesions Sca…

Histologic Diagnosis of Inflammatory Skin Diseases

Radiation dermatitis and panniculitis

Radiation dermatitis and panniculitis Synonyms Radiodermatitis Presentation stereotypical Age and sex Adults of both sexes Distribution of lesions At a site of previous radiation Individual lesions Poikilodermatous patches and ulcers Course Protract…