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Panniculitis

»What is panniculitis?
»Name the various types of panniculitis. How are they classified?
»What is erythema nodosum?
»What is the pathogenesis of erythema nodosum?
»List some of the common underlying conditions associated with erythema nodosum.
»How should a biopsy of erythema nodosum be obtained?
»What are the characteristic microscopic features of erythema nodosum?
»How is erythema nodosum treated?
»What is nodular vasculitis?
»What causes nodular vasculitis?
»Describe the microscopic features of nodular vasculitis.
»What is the differential diagnosis of nodular vasculitis?
»How should nodular vasculitis be treated?
»What are the clinical features of lupus panniculitis?
»Describe the microscopic features of lupus panniculitis.
»What is the significance of diagnosing lupus panniculitis?
»Are sclerema neonatorum and subcutaneous fat necrosis of the newborn the same thing?
»How similar are the microscopic features of sclerema neonatorum and subcutaneous fat necrosis of the newborn?
»Why do these disorders occur in neonates and infants?
»What is pancreatic fat necrosis?
»Are there any characteristic histopathologic features of pancreatic fat necrosis?
»What is the role of a-1 antitrypsin deficiency in the development of panniculitis?
»Name some types of trauma that can produce panniculitis.
»Which infectious organisms can produce panniculitis?
»Describe the role of malignancy in producing panniculitis.
»What is lipodystrophy?
»What is lipoatrophy?
»What is lipohypertrophy?
»Discuss the approach to use when attempting to diagnose an “unknown” case of panniculitis.

 
 
 

Describe the role of malignancy in producing panniculitis.


B-cell lymphoma mimicking panniculitis. (Courtesy of Kenneth E. Greer, MD.)
Fig. 19.10 B-cell lymphoma mimicking panniculitis. (Courtesy of Kenneth E. Greer, MD.)
Malignant infiltrates can sometimes produce subcutaneous nodules that mimic other forms of panniculitis. Malignancies that are capable of producing panniculitis-like lesions include poorly differentiated carcinomas, lymphomas (Fig. 19-10), multiple myeloma, and leukemias. Microscopic clues to the recognition of malignant infiltrates include a monotonous cell population and/or cytologic atypia, “lining up” of atypical cells between collagen bundles, and minimal alteration of connective tissue in the presence of dense cellular infiltration. Also, forms of more traditional inflammatory panniculitis can accompany malignancy, including erythema nodosum, migratory thrombophlebitis, and pancreatic fat necrosis. Therefore, diagnosis again is heavily dependent on biopsy.

Cassis TB, Fearneyhough PK, Callen JP: Subcutaneous panniculitis-like T-cell lymphoma with vacuolar interface dermatitis resembling lupus erythematosus panniculitis, J Am Acad Dermatol 50:465–469, 2004.