Chronic recurrent multifocal osteomyelitis in children: Diagnostic value of histopathology and microbial testing

Chronic recurrent, unifocal or multifocal osteomyelitis (CRMO), an inflamma tory disorder of unknown origin, involves different osseous sites and may b e associated with palmoplantar pustulosis. Bacterial cultures of affected t issue were reported negative in nearly all cases. Radiological and magnetic resonance imaging features of CRMO have been described, but differential d iagnosis remains difficult, including rheumatic diseases, bacterial osteomy elitis, and malignancy. Although definite diagnosis relies on histopatholog ic confirmation by biopsy, histopathologic criteria have not been defined. Because CRMO may be treated with nonsteroidal antiinflammatory drugs, but n ot antibiotics, distinguishing CRMO from bacterial osteomyelitis is of majo r importance. Histopathologic analysis of 12 patients with CRMO indicated a wide variation of reparative changes of bone, but chronic inflammation cou ld not be found at all sites in the same biopsy. The inflammatory infiltrat e was mostly scattered, consisting mainly of lymphocytes, plasma cells, his tiocytes, and also few neutrophil granulocytes. Immunohistochemistry showed a predominance of CD3(+), CD45RO(+) T-cells, which were mainly CD8(+). In addition, CD20(+) B cells and CD68(+) macrophages were abundant in each bio psy specimen. Mild lymphocytic and granulocytic infiltrates were also detec ted in three synovial biopsy specimens obtained from adjacent joints. All b acterial and fungal cultures from native biopsy tissues were negative. Ampl ification of partial-length 16S ribosomal DNA by polymerase chain reaction (PCR) using broad-range eubacterial primers was below the detection limit i n all patients. Because histopathologic features alone may not provide conc lusive evidence, CRMO should be included in the differential diagnosis of c hronic inflammatory bone lesions in children, and the definite diagnosis sh ould be made by the clinical picture, x-ray studies, bone scan, bacterial c ulture, and histopathologic analysis in a multidisciplinary approach. HUM P ATHOL 30:59-65. Copyright (C) 1999 by W.B. Saunders Company.