title: Multicentric reticulohistiocytosis: a unique case with pulmonary fibrosis.
abstract: BACKGROUND
  Multicentric reticulohistiocytosis (MRH) is a rare disease of uncertain etiology that most commonly presents as a papulonodular cutaneous eruption accompanied by erosive polyarthritis. Although MRH is considered a systemic disorder in that it targets skin and joints, involvement of thoracic and visceral organs is uncommon.
  
  
  METHODS
  A woman presented with diffuse cutaneous nodules, and skin biopsy findings revealed classic features of MRH. However, she also manifested severe pulmonary symptoms. A lung biopsy specimen showed prominent histiocytic infiltrates exhibiting the same characteristic morphologic features as those seen in her skin. Furthermore, the lung biopsy findings were significant for a pattern of usual interstitial pneumonia accompanied by notable lymphoid aggregates, a pattern of interstitial lung disease typical of systemic autoimmune and inflammatory conditions.
  
  
  CONCLUSIONS
  These findings are notable because a histiocytic pulmonary infiltrate suggestive of direct pulmonary involvement by MRH is a rare event. In addition, presentation of MRH in the setting of usual interstitial pneumonia is unique. These observations document a new clinical and histopathologic presentation of MRH that is significant for expanding the idea of MRH as a systemic disease while supporting the notion that MRH is promoted by an inflammatory milieu.
authors.affiliation: Department of Pathology, Duke University Medical Center, Durham, NC, USA.
authors.forename: Kelly L
authors.initials: KL
authors.lastname: West
authors.forename: Tom
authors.initials: T
authors.lastname: Sporn
authors.forename: Puja K
authors.initials: PK
authors.lastname: Puri
mesh_terms: D001168:Arthritis / Q000150:complications; D003937:Diagnosis, Differential; D005260:Female; D015614:Histiocytosis / Q000150:complications* / Q000175:diagnosis*; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000209:etiology* / Q000473:pathology; D008875:Middle Aged; D012871:Skin Diseases / Q000209:etiology* / Q000473:pathology