The onset age for MCTO varies widely from infancy through adulthood, however, it most commonly manifests during childhood or adolescence [20]. This condition seems irrelative to inflammation with normal CRP and inflammatory cytokines [2]. The pathophysiology behind MCTO involves an abnormal signal pathway between cells within the joint capsule leading to increased production of matrix metalloproteinases (MMPs). These enzymes are responsible for breaking down collagen fibers which form part of cartilage tissue structure. In individuals with MCTO, this process occurs at an accelerated rate causing rapid erosion and thinning out bone structures around joints affected by disease activity. This leads to instability due to weakened ligaments surrounding these areas making them more prone to injury from everyday activities like gripping objects or typing on keyboards etc. Additionally, there may be associated inflammation caused by the release of inflammatory mediators into synovial fluid further exacerbating symptoms experienced during flare-up episodes where patients experience severe pain swelling stiffness limited range of motion difficulty performing daily tasks involving the use of their hands/wrists [20, 21].

Diagnosing MCTO poses significant challenges for healthcare professionals primarily due to its rarity and similarities with various other conditions such as JIA which may lead to misdiagnosis if not carefully evaluated [3, 22, 23]. The initial symptoms of MCTO often include pain, swelling, stiffness, and limited range of motion in the affected joints. These manifestations are typically bilateral but may not occur simultaneously or symmetrically across all patients [22]. The diagnosis of MCTO requires clinical suspicion based on family history combined with imaging studies showing symmetrical erosions involving multiple small joints, especially those located distally on fingers, toes, wrists, ankles, elbows, knees, hips, shoulders, and spine [24]. However, genetic analysis remains the gold standard to confirm diagnosis [2, 25, 26].

Prognosis depends largely upon how early diagnosis is made degree of disability incurred prior to treatment initiation age gender overall health status person living with multicentric carpotarsal osteolysis. Generally speaking, prognosis is good if appropriate interventions are implemented timely manner while outcomes are less favorable for those who delay seeking medical attention until later stages of progression have already set. With proper care and support individuals diagnosed with this condition can lead relatively normal lives despite having lived with daily challenges posed to them their illness.

However, in daily clinical practice, lots of MCTO patients have suffered a very long period of incorrect diagnosis, following inappropriate treatment, resulting a poor outcomes [1, 22]. The delay in diagnosis has been reported to have been a number of decades when there are atypical manifestations, delayed MRI scanning, a negative result of synovial biopsy, a negative targeted genetic detection and some other reasons [1, 22]. Interestingly, the patient with an MCTO family history often get an early-stage diagnosis and better life standard [22]. This indicates that the detection of genetic mutation is essential for recognizing MOCT patients.

Denosumab is an FDA-approved human monoclonal IgG2 kappa immunoglobulin G antibody designed to target RANKL. The RANKL plays a key role in regulating normal skeletal development by controlling the activity of osteoclasts—cells responsible for breaking down old or damaged bones so they can be replaced with new ones during remodeling processes like growth or repair after injury [27, 28]. By binding RANKL molecules at their active sites on cell surfaces throughout the body’s skeleton system, denosumab prevents them from activating receptors found inside cells involved in stimulating production/activity levels necessary for proper functioning; thus reducing overall rates at which existing bones are broken down while also inhibiting formation/growth rate associated with new ones being created [29, 30]. This makes it useful in the treatment of MOCT, less destruction means more preservation even if there isn’t any increase happening elsewhere within the same area(s) [8]. Even though denosumab has potential prospects for the treatment of MCTO, in the condition of rare prevalence of MCTO with low clinical experience of denosumab, more analysis of MCTO cases or cohort on the effectiveness and safety of denosumab in the treatment of MCTO is intensively required [8, 31].

In our case, when the patient visited our hospital, the scan of MRI on the painful joints was undertaken early. Then the diagnosis of MOCT was considered, and the whole exome sequencing proceeded instead of targeted genes related to MOCT such as TREX1 and MMP9, at an early age. The clinical diagnosis was drawn with the detection of the MAFB gene’s genetic defect. After that, the Denosumab which might be the only potential drug for the MAFB mutation was conducted, even though the drug might only release the symptom but can not heal the damaged bone. Fortunately, no deterioration of joint destruction was shown in the last visit of the patient after about 1.5 years of treatment.

In conclusion, the MRI examination and Whole exome sequencing are recommended to be performed in the early stage of the patient who is suspected of MCTO or suffered bone problems with normal inflammation lab examination. Denosumab might be a potential treatment for MCTO.

The limitation of this report is the lack of pathological results for destructive bone. Longer follow-up duration is necessary in future studies.