THE LANGERHANS CELL HISTIOCYTOSIS X FILES REVEALED

In this day and age, when E-mail, Internet searches, conferences and Medline instantly connect one with the latest discoveries in medicine and science, it may be hard to realize that it took years for many diseases to be fully described. Researchers in the late 1800s from different countries would often be working on the same disease and would not realize that until much later. Langerhans cell histiocytosis (LCH) or histiocytosis X is a good example of this. Its history dates back to 1865 when Dr Thomas Smith published the case of a child four-and-a-half years of age with impetigo and three large holes in the calvarium. These defects were thought to be congenital, but review of the provided drawing now suggests LCH (before the invention of the X-ray in 1895, illustration of the abnormality described in a manuscript was provided in the form of a drawing). The impetigo was cured, but the child died from whooping cough a couple of months later. Dr Smith remarked that the only other specimen he had been able to ®nd showing a similar Ôcongenital de®ciencyÕ was that of an older woman in the Museum of Guy's Hospital (Smith, 1865). In the same period, Paul Langerhans published his landmark manuscript entitled: ÔUÈ ber die Nerven der menschlichen HautÕ when he was a 21-year-old medical student at the Institute of Pathology of the University of Berlin under the mentorship of Professor Virchow (Langerhans, 1868). He used Cohnheim's gold chloride staining technique and described a novel non-pigmentary dendritic cell in the epidermis. He initially regarded these cells as intraepidermal receptors for extracutaneous signals of the nervous system, but corrected this interpretation in 1882. In a short communication, he acknowledged his erroneous assumption: ÔHowever I am now convinced 1⁄4 that my cells are in no way essential for nerve endingsÕ (Langerhans, 1882). Today we know that these cells are bone marrowderived and represent the most peripheral outpost of our immune system. These unique histiocytes are now eponymously referred to as Langerhans cells and the proliferation of these cells is known as Langerhans cell histiocytosis. Paul Langerhans (1847±1888) (Fig 1) was born in Germany. His father as well as both his half-brothers were all physicians. He studied medicine under Haeckel and Virchow and in 1869 he defended his thesis ÔBeitrage zur Mikroskopischen Anatomie der BauchspeicheldruseÕ (Contributions to the Microscopic Anatomy of the Pancreas), which were found in the rabbit. Twenty-®ve years later, Edouard Laguesse found similar cells in the human pancreas and proposed to call them Langerhans islets. After his thesis defence, Langerhans subsequently demonstrated that cinnabar was taken up by white blood corpuscles and never by the red corpuscles, opening the door for Aschoff 's concept of reticuloendothelial system. In 1874, he became Professor Extraordinarius (Full Professor) in Freiburg, but unfortunately a week later he was diagnosed with renal tuberculosis. After a leave of absence, he was released from his duties at the University altogether and left for Madeira. Despite deterioration of his condition, he continued to do research on the fauna of the Atlantic Islands, Madeira in particular. His contributions were numerous and of such quality that in 1909 a polychaete worm was named after him, ÔVerriliopsis LangerhansiÕ, by Pierre Louis Andre Favel. He practiced medicine whenever his health allowed. The majority of his patients were German and British people who lived on the island often for health reasons, most notably tuberculosis. Among the Germans were Mr Ebart and his wife. Two years after Mr Ebart's death, Langerhans married Margaretha Ebart in 1885 in Berlin. Paul Langerhans died on July 2