Name the various types of panniculitis. How are they classified?

Although no single classification seems to be totally satisfactory, disorders tend to be grouped by a combination of histopathologic features and etiologies (Table 19-1). Septal panniculitis refers to a predominance of inflammation involving the connective tissue septae between fat lobules, whereas lobular panniculitis indicates predominant involvement of the fat lobules themselves. Lipodystrophy and lipoatrophy may be end-stage changes of the fat brought about by several different etiologies, including inflammation, trauma, or metabolic or hormonal alterations.

Table 19-1. Major Forms of Panniculitis
	Septal Panniculitis Erythema nodosum Subacute nodular migratory panniculitis Scleroderma panniculitis Lobular and Mixed Panniculitis Nodular vasculitis (erythema induratum) Lupus panniculitis Other types of connective tissue panniculitis Metabolic Derangements Altered melting/solidification points of fat Sclerema neonatorum Subcutaneous fat necrosis of the newborn Pancreatic (enzymatic) fat necrosis Alpha-1 antitrypsin deficiency panniculitis		Traumatic Panniculitis Infectious Panniculitis Malignancy Other Changes of the Fat Lipodystrophy Lipoatrophy Lipohypertrophy