Differential Diagnosis in Dermatopathology

Discussions

Nodular vasculitis and subcutaneous polyarteritis nodosa are inflammatory diseases that affect medium-sized and large arteries situated in fibrous septa of the subcutaneous fat. Both conditions involve the subcutaneous fat mostly, although signs of…

Differential Diagnosis in Dermatopathology

Infundibular cyst vs. Isthmus-catagen cyst

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…

Differential Diagnosis in Dermatopathology

Discussions

These two common cutaneous cysts have several features in common, namely, lining of stratified squamous epithelium and cornified cells in their cavity. We name cysts according to the normal epithelial structure of skin that the lining of the cyst re…

Differential Diagnosis in Dermatopathology

Discussions

Tuberculoid leprosy and sarcoidosis are granulomatous dermatitides that resemble one another histopathologically because both consist of aggregations of epithelioid histiocytes in the dermis and, sometimes, in the subcutaneous fat. Despite the simil…

Differential Diagnosis in Dermatopathology

Differential Diagnosis

Acne vulgaris, erythematous papule Rosacea, erythematous papule 1. Only one follicle involved usually in a 4 mm biopsy specimen 1. Nearly all follicles involved usually in a 4 mm biopsy specimen 2. Suppurative infundibulitis prominent 2. Suppu…

Histologic Diagnosis of Inflammatory Skin Diseases

Erythema nodosum

Erythema nodosum Synonyms Erythema contusiforme Erythema contusiformis Dermatitis contusiformis Erythema nouesux Presentation stereotypical Age and sex Young adults, especially women Distribution of lesions Bilateral and symmetrical over the pretibi…

Differential Diagnosis in Dermatopathology

Nodular vasculitis vs. Subcutaneous polyarteritis nodosa

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

Polyarteritis nodosa

Polyarteritis nodosa Synonyms Periarteritis nodosa Panarteritis nodosa Kussmaul-Maier disease Kussmaul-Maier syndrome Polyarteritis acuta nodosa Presentation stereotypical Age and sex Men mostly Distribution of lesions Bilateral, particularly on the…

Histologic Diagnosis of Inflammatory Skin Diseases

Tuberculosis

Tuberculosis Synonyms Lupus vulgaris Presentation stereotypical Age and sex Any age in both sexes, usually adults Distribution of lesions Localized or widespread, depending on the manifestation specific of the disease Individual lesions Papules, pla…

Differential Diagnosis in Dermatopathology

Tuberculoid leprosy vs. Sarcoidosis

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…