title: Isolated Rosai-Dorfman disease presenting as peripheral mononeuropathy and clinically mimicking a neurogenic tumor: case report.
abstract: BACKGROUND
  Rosai-Dorfman disease is a rare idiopathic disorder of proliferative histiocytes affecting the lymph nodes. It usually manifests as bilateral cervical lymphadenopathy and fever with concurrent polyhyperglobulinemia. Cases involving the nervous system are quite rare; most CNS lesions are located intracranially or arise from the spinal dura or leptomeninges. To our knowledge, there has been no previous report of isolated Rosai-Dorfman disease presenting as peripheral mononeuropathy.
  
  
  METHODS
  We report a 43-year-old female with isolated extranodal Rosai-Dorfman disease in the medial aspect of the right upper arm, which presented as aberrant ulnar neuropathy caused by a mass encasing the right basilic vein and the medial anteriobrachial cutaneous branch of the right ulnar nerve. Preoperative diagnosis was a neurogenic tumor. The patient underwent excision of the mass, and pathologic examination confirmed the diagnosis of Rosai-Dorfman disease.
  
  
  CONCLUSIONS
  An unusual case of extranodal isolated Rosai-Dorfman disease, presenting as peripheral mononeuropathy, is reported. Clinically, it simulated a neurogenic tumor, extending the etiologic spectrum of entrapment neuropathy of the peripheral nerve.
authors.affiliation: Department of Pathology, Chang Gung Memorial Hospital, Kaoshiung Medical Center, Chang Gung University, Hsien, Taiwan, ROC.
authors.forename: H Y
authors.initials: HY
authors.lastname: Huang
authors.forename: C L
authors.initials: CL
authors.lastname: Liang
authors.forename: B Y
authors.initials: BY
authors.lastname: Yang
authors.forename: M T
authors.initials: MT
authors.lastname: Sung
authors.forename: J W
authors.initials: JW
authors.lastname: Lin
authors.forename: W J
authors.initials: WJ
authors.lastname: Chen
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D015618:Histiocytosis, Sinus / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D006801:Humans; D014057:Tomography, X-Ray Computed; D014459:Ulnar Nerve / Q000473:pathology / Q000601:surgery; D020424:Ulnar Neuropathies / Q000209:etiology* / Q000473:pathology / Q000601:surgery