Deep tissue involvement is strongly associated with musculoskeletal (MSK) features in patients with morphea, according to study findings published in Journal of Investigative Dermatology.
Researchers conducted a multicenter, prospective cohort analysis that compared the prevalence of MSK manifestations in pediatric and adult patients with morphea. Data was collected from the National Registry for Childhood-Onset Scleroderma (NRCOS) and the Morphea in Adults and Children (MAC) cohorts.
The final analysis included 605 adult patients and 453 pediatric patients with morphea. A majority of the participants were White (76%) and women or girls (78%). The median age at disease onset in those with MSK extracutaneous manifestations (ECM) was 7.8 (IQR, 5.3-11) years in the pediatric cohort and 29 (IQR, 15-45) years in the adult cohort.
A total of 274 of the 1058 participants (26%) had MSK involvement of the joint or bone, which was defined as a limited range of motion, contracture, limb length discrepancy, or inflammatory arthropathy, with a greater frequency occurring in the pediatric (32%) group vs adults (21%) (P <.001).
Limited range of motion was the most common MSK feature (82%), with 94% of adults with an MSK ECM having range of motion limitation. Children with morphea had more joint contracture, limb length discrepancy, and inflammatory arthropathy compared with the adults with morphea.
The patients with MSK involvement had more active disease, according to the Modified Localized Scleroderma Skin Severity Index (median [IQR], 5 [0-13] vs no MSK involvement, median [IQR], 3 [0-7]; P <.001) and Physician’s Global Assessment of Activity (MSK involvement, median [IQR], 22 [1-46] vs no MSK involvement, median [IQR], 13 [0-35]; P <.001).
Multivariable logistic regression modeling showed that children had an increased risk for MSK involvement compared with adults (adjusted odds ratio [aOR], 1.81; 95% CI, 1.30-2.54; P <.001).
Deep (moderate severe subcutaneous fat and/or soft tissue atrophy) involvement (aOR, 4.19; 95% CI, 2.83-6.33; P <.001) and eosinophilic fasciitis or morphea profunda (aOR, 2.36; 95% CI, 1.25-4.47; P =.008) was associated with an increased risk for MSK involvement. Participants who had lesions limited to the dermis without involvement of the subcutaneous fat or soft tissue (aOR, 0.11; 95% CI, 0.01-0.54; P =.033) were less likely to have MSK involvement.
The presence of subcutaneous fat or soft tissue involvement continued to be a clinical characteristic associated with MSK involvement in multivariable logistic regression (MAC, aOR, 6.21; 95% CI, 3.53-11.65; NRCOS, aOR, 2.96; 95% CI, 1.61-5.57), which supports the validity of the combined data analysis of both cohorts.
In binomial regression modeling, 10-fold cross validation of the predictive value of deep tissue involvement for MSK involvement showed good negative predictive value (90%) and sensitivity (82%) and lower positive predictive value (51%) and specificity (51%). These performance parameters demonstrated that absence of deep involvement is 90% predictive for no MSK involvement.
Limitations of the study include the inherent bias in training and referral pattern of rheumatology and dermatology. Arthralgia, myalgia, and myositis were unable to be assessed, which are predominate variables in MSK features of pediatric patients with morphea.
“Most importantly, we found the biggest risk factor for MSK manifestations is the depth of tissue involvement combined with cutaneous distribution over a joint,” the study authors conclude. “This observation suggests the evaluation of patients should be revised to include this important finding in assessing risk and considering treatment.”
Chen HW, Walker AM, Stein AB, et al. Clinical characteristics associated with musculoskeletal extracutaneous manifestations in pediatric and adult morphea: a prospective, cohort study. J Invest Dermatol. Published online May 2, 2023. doi:10.1016/j.jid.2023.04.010