Clinical findings:
(1) A patient may develop multiple, painful subcutaneous erythematous nodules and plaques.
(2) The lesions are most common on surfaces exposed to trauma.
(3) The nodules may drain a serosanguinous fluid and ulcerate.
(4) The patient may later develop other hallmarks of alpha-1 antitrypsin deficiency such as cirrhosis or emphysema.
Laboratory findings:
(1) Patients usually have a homozygous deficiency of alpha-1-antitrypsin, although lesions may develop in heterozygous patients.
(2) Bacterial cultures are negative.
Microscopic features:
(1) There is a lobular panniculitis with neutrophils, lymphocytes and macrophages.
(2) Collagen is destroyed as the lesion progresses. Lobules of adipose tissue may become detached and surrounded by an inflammatory cell infiltrate.
(3) Liquefactive necrosis may develop in lesions that go on to drain and ulcerate.
(4) Vascular lesions may be present.
(5) Immunofluorescent staining for IgM and C3 may be positive.
(6) Special stains for bacteria, mycobacteria and fungi are negative.
Differential diagnosis:
(1) bacterial cellulitis
(2) other forms of lobular panniculitis
