Histiocytosis X

Langerhans cell histiocytosis is a group of syndromes of unknown aetiology characterised by the development of granulomatous lesions with abnormal proliferation of histiocytes. The abnormal histiocytic cell in this disease had been identified as the Langerhans cell. This condition represents a disorder of regulation of of the normal proliferation of histiocytes.

Pulmonary lesions are the commonest manifestation followed by bone involvement.

Langerhans cell histiocytosis includes a variety of clinical syndromes including, in decreasing severity:

• Letterer-Siwe disease
• Hand-Schuller-Christian disease
• eosinophilic granuloma of bone

These disorders were previously referred to as histiocytosis X, but are now categorised under the term Langerhans cell histiocytosis to reflect the cell type responsible for the histiocytosis.

Reference

1. DeCaprio M et al. Diagnosis and management of langerhans cell histiocytosis. J Am Acad Orthop Surg. 2014 Oct;22(10):643-52.