title: Pancytopenia in a patient with cystinosis secondary to myelosuppression from cystine crystal deposition: a case report.
abstract: BACKGROUND
  Cystinosis is a rare metabolic genetic disorder caused by a mutation in the cystinosin lysosomal cystine transporter gene. Clinically, it is characterized by systemic accumulation of cystine crystals in tissues causing end-organ dysfunction in the kidney, eyes, muscles, and other organs in the body. In very rare cases, it can also involve the bone marrow and the resulting cystine crystal deposition can cause myelosuppression leading to pancytopenia.
  
  
  METHODS
  Here we report the case of a 26-year-old white woman with cystinosis and other complex medical comorbidities who developed pancytopenia. She was worked up extensively and ruled out for common causes of pancytopenia (infectious disorders, vitamin deficiencies secondary to gastrointestinal malabsorption, rheumatologic, and hematologic disorders). On bone marrow biopsy she was found to have extensive deposits of cystine crystals, which was thought to be the cause of her myelosuppression leading to her pancytopenia. As a result, by treating her underlying cystinosis more aggressively we were able to observe an improvement in her pancytopenia a few months afterwards.
  
  
  CONCLUSIONS
  Pancytopenia secondary to myelosuppression from cystine crystal deposition in the bone marrow is a very rare complication that has been reported in only a handful of case reports. This case illustrates the importance of keeping a broad differential diagnosis and systematically ruling out common causes of pancytopenia. It also demonstrates the importance of bone marrow biopsies in the evaluation of unexplained pancytopenia.
authors.affiliation: Department of Medicine, Division of Hematology Oncology, University of California Irvine Medical Center, 101 The City Drive South, Orange, CA, 92868, USA. ylyou@uci.edu.
authors.forename: Yung
authors.initials: Y
authors.lastname: Lyou
authors.affiliation: Department of Pathology, University of California Irvine Medical Center, 101 The City Drive South, Orange, CA, 92868, USA. zhaox@uci.edu.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Medicine, Division of Hematology Oncology, University of California Irvine Medical Center, 101 The City Drive South, Orange, CA, 92868, USA. cnangia@uci.edu.
authors.forename: Chaitali S
authors.initials: CS
authors.lastname: Nangia
mesh_terms: D000328:Adult; D001853:Bone Marrow / Q000473:pathology; D003543:Cysteamine / Q000627:therapeutic use; D003553:Cystine / Q000378:metabolism*; D065104:Cystine Depleting Agents / Q000627:therapeutic use; D003554:Cystinosis / Q000150:complications* / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D010198:Pancytopenia / Q000150:complications* / Q000175:diagnosis*
chemical_list: D065104:Cystine Depleting Agents; D003553:Cystine; D003543:Cysteamine