Endogenous lipoid pneumonia associated with undifferentiated connective tissue disease (UCTD)

Lipoid pneumonia is a rare pulmonary disease, a form of pneumonia that has no classical radiological appearance, thus it can imitate other lung diseases. Lipoid pneumonia is usually classified into two major groups, depending on whether the source of oil/fat in the respiratory tract is from an exogenous or endogenous source. Undifferentiated connective tissue disease is a term used by rheumatologists to define a group of diffuse connective tissue disorders that lack definitive characteristics of any particular well-defined disorder.

A case study is reported of concomitant undifferentiated connective tissue disease and endogenous lipoid pneumonia.

Histologically the macrophages appeared filled with lipid and were similar to atherosclerotic foam cell macrophages. Antibiotic and antimycotic treatments were ineffective. However, with concomitant steroid treatment, the patient exhibited absence of lung infiltration as well as other symptoms and was discharged. Therefore it is concluded that the lipoid pneumonia was steroid dependent.

Since the patient's condition responded to steroid treatment, and it is clear that steroids inhibit phospholipase activity, the authors speculate that the subsequent decreased endoperoxide production may diminish lipid uptake by macrophages via decreasing modification of LDL or other lipid sources.