Histologic Diagnosis of Inflammatory Skin Diseases

Crohn’s disease

…re related overtly to the infiltrates of neutrophils, as when suppuration in association with pseudocarcinomatous proliferation of infundibular keratocytes is surrounded by epithelioid histiocytes arrayed in a palisade. At other times, however, granu…

Differential Diagnosis in Dermatopathology

Discussions

…niculitis that demonstrates every aspect of inflammation from suppuration through granulomas to fibrosis. The artery in nodular vasculitis displays extensive necrosis of smooth muscle and degeneration of collagen bundles. As a result, the internal el…

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

…the cysts that are spewed into the dermis. At first there is suppuration, then granulomatous inflammation, and, last, fibrosis. Historically, follicular cysts of the isthmus-catagen type have been called tricholemmal cysts, pilar cysts, sebaceous cy…

Differential Diagnosis in Dermatopathology

Discussions

…al, when epithelioid histiocytes monopolize in the absence of suppuration or necrosis. With the assistance of the electron microscope, however, a few lepra bacilli may be detected, albeit with difficulty, in histiocytes of tuberculoid leprosy. In con…

Differential Diagnosis in Dermatopathology

Differential Diagnosis

…uppurative inflammation 6. Granulomas often in the absence of suppuration 7. No necrosis in association with granulomas 7. Caseous necrosis sometimes in the center of granulomas 8. Few, if any, lymphocytes or plasma cells 8. Notable infiltrate of…

Histologic Diagnosis of Inflammatory Skin Diseases

Erythema nodosum

…titium of fibrous septa in the subcutaneous fat; tiny foci of suppuration in septa exceptionally Neutrophils scattered at the periphery of fat lobules, sometimes in conjunction with macrophages that display foamy cytoplasm Foci of neutrophils surroun…

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

…s adiposus extensively in the form of necrosis of adipocytes, suppuration, granulomatous inflammation, and fibrosis. Rarely, polyarteritis nodosa is accompanied by formidable panniculitis, as well as arteritis. Of biopsy specimens of arteritis receiv…

Histologic Diagnosis of Inflammatory Skin Diseases

Tuberculosis

…nd of the effects of them. Extensive necrosis (caseation) and suppuration result. Concurrent with these events, the bacilli enter lymphatics and travel to lymph nodes in the region, where they ravage those structures. The combination of the primary s…