Differential Diagnosis in Dermatopathology

Psoriasis vs. Nummular dermatitis

An inflammatory process that consists of tiny papules covered by prominent scales and localized typically to the “seborrheic region,” namely, scalp, forehead, eyebrows, malar eminences, paranasal and nasolabial folds, and retroauricular…

Histologic Diagnosis of Inflammatory Skin Diseases

Images

Images 10.2.1A: Perivascular dermatitis, spongiotic and slightly psoriasiform + 10.2.1B: Slight edema of the papillary dermis and scale-crust = Nummular dermatitis  Changes such as these are indistinguishable from those of allergic contac…

Histologic Diagnosis of Inflammatory Skin Diseases

Toxic shock syndrome

Toxic shock syndrome Synonyms TSS Presentation stereotypical Age and sex Women using super-absorbent vaginal tampons especially, but possible in both sexes consequent to any infection by pathogenic bacteria, particularly Staphylococcus aureus, inclu…

Histologic Diagnosis of Inflammatory Skin Diseases

Gianotti-Crosti disease

…Pityriasis rosea usually is marked by less spongiosis and less acanthosis, except for the presentation of it in some dark-skinned individuals. Allergic contact dermatitis and nummular dermatitis tend to exhibit more psoriasiform acanthosis, more spon…

Histologic Diagnosis of Inflammatory Skin Diseases

Psoriasis

Psoriasis Presentation stereotypical Age and sex Persons of any age and of both sexes Distribution of lesions Localized, e.g., single papule or plaque, or universal, i.e., erythroderma; between these extremes, a preference for elbows and knees, scal…

Histologic Diagnosis of Inflammatory Skin Diseases

Syphilis

Syphilis Synonyms Lues Presentation stereotypical Age and sex Young, sexually active adults of both sexes Distribution of lesions Localized (usually to genitalia) as a chancre of primary syphilis, widespread lesions in secondary syphilis, and locali…

Differential Diagnosis in Dermatopathology

Discussions

Psoriasis and nummular dermatitis share several attributes histopathologic, namely, parakeratosis that often is accompanied by serum, psoriasiform acanthosis, spongiosis, edema of the papillary dermis, and an infiltrate of lymphocytes mostly around…

Histologic Diagnosis of Inflammatory Skin Diseases

Pityriasis rosea

…titial infiltrate of lymphocytes Edema of the papillary dermis Acanthosis Prominent spongiosis focally Mounds of parakeratosis or scale-crusts in foci Late Superficial perivascular infiltrate of lymphocytes Slight psoriasiform acanthosis; little, i…