[Associated Langerhans cell histiocytosis and Erdheim-Chester disease]

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis with multiple organ involvement affecting middle-aged adults. A case of ECD associated with Langerhans cell histiocytosis (LCH) is reported herein.

A 75-year-old woman presented maculopapular skin lesions on her trunk, associated with constrictive pericarditis and pleurisy present for 1 year. The skin biopsy militated in favour of LCH since it revealed a histiocytic infiltrate with a positive CD1a marker at immunohistochemistry (IHC). The association with ECD was diagnosed on the basis of pericarditis, periaortitis, pleurisy, pulmonary involvement and retroperitoneal fibrosis. The patient was treated with interferon-α2a with good initial results, but died from septic shock a year and a half later, a few months after discontinuing interferon due to poor tolerability.

The clinical, radiographic and histological arguments in favour of ECD clearly differ from those for LCH. However, as already reported, the two illnesses may be associated, thus underlining the possible existence of a link between these two histiocytic proliferations emanating from the same medullary precursor. Two hypotheses have been advanced in an attempt to explain this association: the first involves a stimulus that might lead to independent proliferation of the two cell lines while the second suggests the existence of a transformation pathway from one form of proliferation to the other.

Screening for associated ECD should be routinely performed in patients presenting LCH with signs evocative of ECD.