The Weber-Christian syndrome (relapsing nodular panniculitis) displays a clinical spectrum varying from short, self-limited, or intermittent disease episodes to persistent disease with fatal outcome. Inflamed adipose tissue is exclusively subcutaneous in some patients and is both subcutaneous and perivisceral in others. Inflammation of fat may induce a focal cutaneous or a systemic extracutaneous histiocytic proliferative response in which hemophagocytosis may be a frequent characteristic. Major causes of death--sepsis, hepatic failure, hemorrhage, and thrombosis--are identical in the patients with and without the systemic histiocytic proliferation. Inflammation in fat, of and by itself, may be associated with significant morbidity and mortality, regardless of specific histopathology or inciting factors.