Idiopathic multicentric osteolysis: a rare disease mimicking juvenile chronic arthritis

Multicentric Carpotarsal Osteolysis Syndrome in a Mother and Daughter with a MAFB Missense Variant and Natural History of the Disease

Multicentric carpotarsal osteolysis syndrome (MCTO; MIM #166300) is a rare skeletal disorder characterized by osteolysis affecting particularly the carpal, metacarpal, and tarsal bones, although other bones might be involved. MCTO is an autosomal dominant disease caused by heterozygous variants in the MAFB gene, frequently misdiagnosed as juvenile rheumatoid arthritis due to similar clinical manifestations. This study reports the first Brazilian family diagnosed with MCTO with progressive osteolysis of the carpal and tarsal bones, presenting a c.161C>T (p.Ser54Leu) heterozygous variant in the MAFB gene, describing the clinical, radiological, and molecular findings, compared with literature data, and discussing the different clinical and molecular diagnosis, as well as the natural history of the disease. Since MCTO is a disorder with progressive symptoms, an early diagnosis is important to avoid unnecessary investigations and treatments and to provide the proper follow-up.

Absence of MMP2 mutation in idiopathic multicentric osteolysis with nephropathy

The genetic basis of idiopathic multicentric osteolysis with nephropathy is unknown. This disorder is typically a sporadic, but sometimes an autosomal dominant, condition featuring carpal-tarsal destruction and nephropathy causing renal failure. Loss-of-function mutation within the gene encoding matrix metalloproteinase 2 (MMP2) causes the autosomal recessive disorder nodulosis-arthropathy-osteolysis syndrome characterized by carpal-tarsal destruction, subcutaneous nodules, and generalized osteoporosis. We questioned whether sporadic idiopathic multicentric osteolysis with nephropathy is allelic with nodulosis-arthropathy osteolysis syndrome and undertook sequence analysis of the matrix metalloproteinase 2 gene in three unrelated affected boys. Although symptoms appeared by age 2 years, idiopathic multicentric osteolysis was diagnosed at ages 5, 5, and 12 years with flares of pain and limited motion or swelling of wrists, ankles, elbows, knees, and shoulders. Proteinuria was present on referral at ages 8, 7, and 12 years, respectively. Kidney transplantation was necessary for one boy at age 17 years. Coding exons and adjacent mRNA splice sites of the matrix metalloproteinase 2 gene were analyzed by polymerase chain reaction amplification and DNA sequencing. Matrix metalloproteinase 2 gene analysis was negative for mutation in the three patients. Sequence analysis of the matrix metalloproteinase 2 gene shows sporadic idiopathic multicentric osteolysis with nephropathy is not allelic to nodulosis-arthropathy-osteolysis syndrome. The genetic bases of idiopathic multicentric osteolysis disorders remain unknown.

Desmoid tumors in a woman with idiopathic multicentric osteolysis: result of three etiologic factors or coincidence?

Desmoid tumors developed on the toes of a young woman with idiopathic multicentric osteolysis (IMO) after amputation of the toenails. A summary of IMO is given, and a review of literature for the etiologic factors of desmoid tumors is added.