title: Bone pathologic fracture revealing an unusual association: coexistence of Langerhans cell histiocytosis with Rosai-Dorfman disease.
abstract: BACKGROUND
  The coexistence of Rosai-Dorfman disease (RDD) with Langerhans cell histiocytosis (LCH) is very rare, as to date only 17 cases have been reported in the english literature. The pathophysiology of this uncommon co-occurrence still remains enigmatic and a subject of various speculations.
  
  
  METHODS
  We report a case of a 30-year-old female patient who presented with a pathologic fracture of the left proximal femur. Her medical history was unremarkable, there were no fever, skin lesions, lymphadenopathy or other organomegaly at physical examination. X-ray radiograph of the fractured femur showed an isolated and ill-defined osteolytic lesion. The histopathological analysis of biopsies from this lesion were consistent with a combined RDD-LCH of the bone.
  
  
  CONCLUSIONS
  Combined RDD-LCH is a very rare phenomenon, whose pathophysiology still remains unclear and a subject of various speculations.
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.
authors.forename: Boubacar
authors.initials: B
authors.lastname: Efared
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.
authors.forename: Asmae
authors.initials: A
authors.lastname: Mazti
authors.affiliation: Department of orthopaedics and traumatology, Hassan II University hospital, Fès, Morocco.
authors.forename: Badarou
authors.initials: B
authors.lastname: Chaibou
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Atsame-Ebang
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.
authors.forename: Ibrahim Sory
authors.initials: IS
authors.lastname: Sidibé
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.
authors.forename: Layla
authors.initials: L
authors.lastname: Tahiri
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.
authors.forename: Fatimazahra
authors.initials: F
authors.lastname: Erregad
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.|Faculty of Medicine and Pharmacology, Sidi Mohamed Ben Abdellah University, Fès, Morocco.
authors.forename: Nawal
authors.initials: N
authors.lastname: Hammas
authors.affiliation: Department of orthopaedics and traumatology, Hassan II University hospital, Fès, Morocco.|Faculty of Medicine and Pharmacology, Sidi Mohamed Ben Abdellah University, Fès, Morocco.
authors.forename: Abdelmajid
authors.initials: A
authors.lastname: El Mrini
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.|Faculty of Medicine and Pharmacology, Sidi Mohamed Ben Abdellah University, Fès, Morocco.
authors.forename: Hinde
authors.initials: H
authors.lastname: El Fatemi
authors.affiliation: Departement of pathology, Hassan II University hospital, Fès, Morocco.|Faculty of Medicine and Pharmacology, Sidi Mohamed Ben Abdellah University, Fès, Morocco.
authors.forename: Laila
authors.initials: L
authors.lastname: Chbani
keywords: Langerhans cell histiocytosis; Pathology; Rosai-Dorfman disease