title: Focal nodular and diffuse haematopoietic marrow hyperplasia in patients with underlying malignancies: a radiological mimic of malignancy in need of recognition.
abstract: OBJECTIVE
  To report the authors' experience of focal nodular haematopoietic marrow hyperplasia (FNHMH) and diffuse haematopoietic marrow hyperplasia (DHMH) clinically masquerading as skip, distant, or disseminated metastasis in seven patients with underlying malignant neoplasms.
  
  
  METHODS
  Five patients with FNHMH and two with DHMH mistaken radiologically as skip and disseminated metastasis, respectively, were compared and contrasted with four patients with osteosarcomas and two with chondrosarcomas harbouring skip metastasis, noting the temporal relationship with their haematological profile.
  
  
  RESULTS
  FNHMH and DHMH were undetectable by plain radiography and computed tomography (CT) except one showing subtle sclerosis on CT. They showed either isointense or hyperintense, but not hypointense, attenuation at T1-weighted imaging, and all showed hyperintense attenuation at T2-weighted MRI relative to skeletal muscle. Of the five patients who underwent bone scintigraphy, one showed mildly increased uptake, and one out of two showed markedly increased 2-[18F]-fluoro-2-deoxy-d-glucose (FDG)-positron-emission tomography (PET) uptake. The rates for sarcoma skip metastasis by plain radiography, CT, MRI, and bone scintigraphy were 40%, 66.7%, 100%, and 66.7%, respectively. At MRI, 60% showed hypointense and 40% isointense attenuation at T1-weighted, 80% hyperintense and 20% hypointense attenuation at T2-weighted imaging. Combined FDG-PET and CT, which was performed in only one patient, failed to show the skip metastasis. Not every patient with FNHMH or DHMH received granulocyte colony-stimulating factor (GCSF), but all had low or falling haemoglobin levels, which may thus be the prime cause for HMH.
  
  
  CONCLUSIONS
  Due to overlapping radiological features, FNHMH and DHMH are great radiological mimics of malignancy. In some cases, needle biopsy is required for their definitive differentiation.
authors.affiliation: Department of Clinical Pathology, Tuen Mun Hospital, Hong Kong. Electronic address: louistcchow@gmail.com.
authors.forename: L T C
authors.initials: LT
authors.lastname: Chow
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Hong Kong.
authors.forename: A W H
authors.initials: AW
authors.lastname: Ng
authors.affiliation: Department of Orthopaedics and Traumatology, Prince of Wales Hospital, Hong Kong.
authors.forename: S K C
authors.initials: SK
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D000328:Adult; D019046:Bone Marrow Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging*; D002648:Child; D003937:Diagnosis, Differential; D003951:Diagnostic Errors / Q000517:prevention & control; D003952:Diagnostic Imaging / Q000379:methods*; D005188:False Negative Reactions; D019337:Hematologic Neoplasms / Q000097:blood* / Q000150:complications / Q000000981:diagnostic imaging*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006454:Hemoglobins