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Chronic Recurrent Multifocal Osteomyelitis Mimicked in Childhood Hypophosphatasia
Author(s) -
Whyte Michael P,
Wenkert Deborah,
McAlister William H,
Mughal M Zulf,
Freemont Anthony J,
Whitehouse Richard,
Baildam Eileen M,
Coburn Stephen P,
Ryan Lawrence M,
Mumm Steven
Publication year - 2009
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.090308
Subject(s) - hypophosphatasia , chronic recurrent multifocal osteomyelitis , medicine , compound heterozygosity , osteosclerosis , osteomyelitis , osteitis , bone pain , rickets , pathology , osteomalacia , surgery , alkaline phosphatase , osteoporosis , mutation , biochemistry , chemistry , vitamin d and neurology , gene , enzyme
Hypophosphatasia (HPP) is the inborn error of metabolism characterized by low serum alkaline phosphatase (ALP) activity caused by inactivating mutations within TNSALP , the gene that encodes the “tissue‐nonspecific” isoenzyme of ALP (TNSALP). In HPP, extracellular accumulation of inorganic pyrophosphate, a TNSALP substrate, inhibits hydroxyapatite crystal growth leading to rickets or osteomalacia. Chronic recurrent multifocal osteomyelitis (CRMO) is the pediatric syndrome of periarticular pain and radiographic changes resembling infectious osteomyelitis but without lesional pathogens. Some consider CRMO to be an autoinflammatory disease. An unrelated boy and girl with the childhood form of HPP suffered chronic, multifocal, periarticular pain, and soft tissue swelling. To investigate this unusual complication, we evaluated their cumulative clinical, biochemical, radiological, and histopathological findings and performed mutation analysis of their TNSALP alleles. The earliest radiographic disturbances were typical of childhood HPP. Subsequently, changes consistent with CRMO developed at sites where there was pain, including lucencies, osteosclerosis, and marked expansion of the underlying metaphyses. Bone marrow edema was shown by MRI. Biopsies of affected bone showed nonspecific histopathological findings and no pathogens. The boy was heterozygous (c.1133A>T, p.D378V) and the girl compound heterozygous (c.350A>G, p.Y117C, c.400_401AC>CA, p.T134H) for different TNSALP missense mutations. Nonsteroidal anti‐inflammatory drugs diminished their pain, which improved or resolved at maturity. HPP should be considered when CRMO is a diagnostic possibility. Metaphyseal radiographic changes and marrow edema associated with periarticular bone pain and soft tissue swelling suggestive of osteomyelitis can complicate childhood HPP.