Calcinosis in Rheumatic Disease Is Still an Unmet Need: A Retrospective Single-Center Study

Patients with immune-mediated rheumatic disease-related calcinosis comprise a subgroup at risk of encountering a more severe clinical outcome. Early assessment is pivotal for preventing overall disease progression, as calcinosis is commonly overlooked until several years into the disease and is considered as a ‘non-lethal’ manifestation. This single-center retrospective study explored the prevalence, clinical associations, and impact on survival of subcutaneous calcinosis in 86 patients with immune-mediated rheumatic diseases (IMRD). Calcinosis predominantly appeared in individuals with longstanding disease, particularly systemic sclerosis (SSc), constituting 74% of cases. Smaller calcinosis lesions (≤1 cm) were associated with interstitial lung disease, musculoskeletal involvement, and digital ulcerations, while larger lesions (≥4 cm) were associated with malignancy, severe peripheral artery disease, and systemic arterial hypertension. The SSc calcinosis subgroup exhibited a higher mean adjusted European Scleroderma Study Group Activity Index score than those without. However, survival rates did not significantly differ between the two groups. Diltiazem was the most commonly used treatment, and while bisphosphonates reduced complications related to calcinosis, complete resolution was not achieved. The findings underscore current limitations in diagnosing, monitoring, and treating calcinosis, emphasizing the need for further research and improved therapeutic strategies to improve patient care and outcomes.


Introduction
Soft-tissue calcifications have been classified into five major types: dystrophic, metastatic, idiopathic, iatrogenic, and calciphylaxis [1].In immune-mediated rheumatic diseases (IMRD), dystrophic calcification, characterized by the accumulation of calcium salts in areas of persistent inflammation or previous injury, with normal serum calcium and phosphorus levels, is common [2].The etiology of calcinosis remains uncertain, with proposed mechanisms including microvascular changes [3][4][5], the dysregulation of components of the innate immune system [6], and associations with specific autoantibodies (e.g., anti-MDA5, anti-NXP2, anti-PM/Scl, anti-centromere, and anti-topoisomerase I) [7].Additional theories postulate contributions from recurrent trauma and abnormalities in bone matrix proteins [4,8].The prevalence of calcinosis is often underestimated, leading to delayed diagnosis and long-term complications.It may vary depending on the subset of the disease: 20-40% in systemic sclerosis (SSc) patients, with 25-40% in limited cutaneous SSc [9,10]; 17% in systemic lupus erythematosus (SLE) [11]; and 30-70% in dermatomyositis (DM), particularly in childhood-onset cases [12,13].Additionally, calcinosis, though rare, has been reported in polymyositis (PM), rheumatoid arthritis (RA), localized scleroderma (i.e., morphea), mixed connective disease (MCTD), and primary Sjögren syndrome (pSS) [9,14].Common clinical symptoms of calcinosis include pain, recurrent local inflammation, ulcers with infections, and deformities, causing functional impairment.Calcinosis can also lead to compression neuropathies, with motor and sensory deficits, with a higher likelihood of skin ulceration in areas like the forearm, elbows, fingers (especially the volar aspect of fingertips), and metacarpophalangeal and interphalangeal joints [15].Radiological investigations can contribute to early diagnosis, treatment guidance, and prognosis assessment [16].The Scleroderma Clinical Trials Consortium (SCTC) has developed a validated radiographic scoring system for hand SSc-related calcinosis, considering factors like area, density, number, and location to estimate calcinosis burden [17].Currently, the absence of established guidelines and standardized tools hinders the evaluation of pharmacologic treatments for calcinosis in IMRD.Additionally, there are no established patient-reported outcome measures (PROMs) for IMRD-related calcinosis, except for the SCTC Mawdsley Calcinosis Questionnaire, which is currently undergoing validation [18].Despite this therapeutic challenge, promising emerging approaches include the systemic administration of sodium thiosulfate or immunosuppressant agents [19].Surgery may be the only treatment option in some cases, but outcomes are unpredictable [20].Demographic characteristics and clinical features of individuals with IMRD-related calcinosis have been scarcely documented, with a focus on SSc and myositis patients.Consequently, a notable deficiency exists in comprehensive data regarding the clinical course, long-term follow-up, associations with other disease-specific characteristics, and efficacy of treatment options for this condition.Our ongoing research, conducted at a tertiary-care rheumatology unit with access to a multidisciplinary committee, aims to fill this gap by identifying clinical and immunological prognostic factors and evaluating practical treatment approaches for IMRD-related calcinosis.

Study Design
This work is a retrospective cross-sectional observational study and was conducted in the Rheumatology Department of "Saint Mary's" Clinical Hospital, in Bucharest, Romania, between January 2000 and December 2022.Data from 86 selected patients were collected retrospectively from hospital charts.This study was conducted according to the guidelines of the Declaration of Helsinki and was approved by the Ethics Committee for Research of the "Carol Davila" University of Medicine and Pharmacy, Bucharest.Informed consent was waived due to the retrospective nature of the study.

Treatment and Outcomes
We documented a range of therapeutic approaches, including medications, surgeries, and complementary treatments.We also conducted a thorough evaluation of treatment outcomes, assessing factors such as wound healing, changes in lesion size and number, and the occurrence of complications.Patients' responses to therapy were categorized into four grades: complete, partial, none, or unknown.Complete response denoted the total resolution of an individual lesion without subsequent recurrence in the same area.The partial response indicated regression or recurrence of a lesion that had previously regressed or completely healed.No response was attributed to the persistence of old lesions, with or without the emergence of new ones.

Data Analysis
For analysis, individual cases were paired with controls based on age and gender.Our cohort comprised 86 patients with IMRD and calcinosis, while 90 IMRD patients without calcinosis were selected as the control group.Descriptive statistics, such as median values, standard deviations (SD), or percentages, were employed to summarize data.Clinical and immunological variables, with potential predictive value for calcinosis development, were entered into a logistic regression analysis.Comparisons between groups, stratified by the topographic distribution of calcinosis, were conducted using Fisher's exact test or a Wilcoxon ranked test, as appropriate.

General Description of the Study Lot
Within the cohort, calcinosis related to IMRD was observed in 86 individuals, representing 9.7% of total cases.The calcinosis group consisted of 71 females and 15 males, with a mean age of 52.6 years (±14.3)and an average disease duration of 5.6 years (±3.1).The time from disease onset to calcinosis development varied significantly among different IMRDs, with a notably shorter duration in diffuse cutaneous SSc (dcSSc) compared to Sjögren's syndrome (1.1 vs. 21.5 years, p < 0.001).The distribution of cases and patients' characteristics are summarized in Table 1.Among the 8 patients diagnosed with scleroderma overlap-related calcinosis, limited cutaneous SSc (lcSSc) and PM emerged as the prevailing disease phenotypes, with additional associations observed with RA, DM, pSS, and psoriatic arthritis.

Anatomic Distribution of Calcinosis
All clinically suspected calcifications were confirmed through various imaging studies (radiography, computed tomography, MRI, or ultrasound).Skin biopsy was used to confirm the diagnosis in only two patients.While in patients with lcSSc, the hands (96%) were the most frequently affected sites, followed by areas exposed to frequent pressure such as the elbows and knees (76%), in dcSSc patients, the distribution was more widespread.Patients with PM/DM and overlap syndromes often presented with multiple affected sites at disease onset, notably in the pelvic girdle, lower limbs, and extremities.Furthermore, 73% of these patients had calcifications in less common areas such as the maxillary sinuses, cervical spine, chest, and buttocks, often with nonspecific symptoms.In SLE patients, the upper limbs and abdominal wall were the most commonly affected areas (Figure 1).
Diagnostics 2024, 14, x FOR PEER REVIEW 5 of 12 confirm the diagnosis in only two patients.While in patients with lcSSc, the hands (96%) were the most frequently affected sites, followed by areas exposed to frequent pressure such as the elbows and knees (76%), in dcSSc patients, the distribution was more widespread.Patients with PM/DM and overlap syndromes often presented with multiple affected sites at disease onset, notably in the pelvic girdle, lower limbs, and extremities.Furthermore, 73% of these patients had calcifications in less common areas such as the maxillary sinuses, cervical spine, chest, and buttocks, often with nonspecific symptoms.
In SLE patients, the upper limbs and abdominal wall were the most commonly affected areas (Figure 1).

Correlation Analyses between Different IMRD and Subcutaneous Calcinosis
The analyses primarily centered on SSc patients, given their predominance within the study cohort.Assessing this aspect for other IMRD subsets posed challenges due to limited sample sizes and heterogeneous presentations.Factors correlated with calcinosis in all the SSc patients encompassed disease duration, female gender, digital ulcers (DU), and severe GI involvement (Table 2).

Correlation Analyses between Different IMRD and Subcutaneous Calcinosis
The analyses primarily centered on SSc patients, given their predominance within the study cohort.Assessing this aspect for other IMRD subsets posed challenges due to limited sample sizes and heterogeneous presentations.Factors correlated with calcinosis in all the SSc patients encompassed disease duration, female gender, digital ulcers (DU), and severe GI involvement (Table 2).In the SSc subgroup, univariate logistic regression analysis showed that lesions ≤ 1 cm were associated with anti-topoisomerase antibodies, interstitial lung disease, articular involvement, and DU, while those ≥4 cm were linked to anti-Pm/Scl antibodies, symptoms of muscle weakness, severe peripheral artery disease, systemic arterial hypertension, malignancy, and higher disease activity reflected by the EScSG-AI (Table 3).Moreover, PM/Scl antibodies were correlated with longer disease duration [OR 4.50 95% CI 1.39-14.6,p = 0.01], whereas anti-TIF1-γ was associated with a lower calcinosis prevalence in adult DM [OR 0.80, 95% CI 0.85-0.99,p = 0.03].

Treatment of Calcinosis Cutis
All IMRD-related calcinosis patients received various treatments, including calcium channel blockers such as diltiazem (18/86 patients, 120 to 480 mg/day) or nifedipine (8/86 patients, 20 mg/day), bisphosphonates (alendronic acid in 11% of patients, ibandronic acid in 7% of patients, risedronic acid and zoledronate in 2% of patients), as well as colchicine and minocycline (Figure 2).Warfarin sodium or intravenous immunoglobulin were not prescribed, and neither were topical or intralesional steroids, nor sodium thiosul-fate.Surgical excision was performed in only one patient due to pain and vascular compression caused by a massive calcification on the index finger.Diltiazem was the most frequently used first-line therapy for calcinosis, with a median duration of 68 (12-240) months.Combining colchicine (1 mg/day) with diltiazem for calcinosis-related complications resulted in a partial response in 16 out of 27 patients over an average of a 28 month duration.Additionally, among 15 patients with painful or ulcerated nodules who were prescribed minocycline (50-100 mg daily), 12 showed a partial response.The earliest improvement was observed after 2 weeks, with an average resolution time of 2.4 ± 2.8 months.The further analysis of data on immunomodulatory agent use, including type and number, for all IMRD-related calcinosis patients revealed no significant correlation between the extent of calcinosis-affected areas and the number of previous immunomodulatory agents used.
prescribed, and neither were topical or intralesional steroids, nor sodium thiosulfate.S gical excision was performed in only one patient due to pain and vascular compressi caused by a massive calcification on the index finger.Diltiazem was the most frequen used first-line therapy for calcinosis, with a median duration of 68 (12-240) months.Co bining colchicine (1 mg/day) with diltiazem for calcinosis-related complications resul in a partial response in 16 out of 27 patients over an average of a 28 month duration.A ditionally, among 15 patients with painful or ulcerated nodules who were prescrib minocycline (50-100 mg daily), 12 showed a partial response.The earliest improvem was observed after 2 weeks, with an average resolution time of 2.4 ± 2.8 months.The f ther analysis of data on immunomodulatory agent use, including type and number, all IMRD-related calcinosis patients revealed no significant correlation between the ext of calcinosis-affected areas and the number of previous immunomodulatory agents us

Outcomes and Survival
A proportion of 58% (49/86) of patients experienced calcinosis-related complications, with around 42% of requiring hospitalization for infections and wound care debridement.Of these, 27 individuals (26 with SSc and 1 with DM) had ≥4 admissions per year.Common complications included tenderness (53%), functional joint impairment (42%), and fistulas (37%).Patients with calcinosis in the finger/thumbs had a higher incidence of complications compared to those with calcinosis elsewhere (86.36% vs. 51.57%,p = 0.002).In specific IMRD subsets, such as SSc, patients with Raynaud's phenomenon, DU, and GI involvement, were more prone to recurrent complications related to calcinosis (Table 4).In DM and scleroderma overlap PM, subcutaneous tumoral deposits led to joint limitations and secondary infections, while SLE patients experienced small calcifications causing localized pain without significant inflammation.Nine patients passed away, primarily due to causes such as respiratory failure (3 patients), ventricular arrhythmias (2 patients), and scleroderma renal crisis (1 patient).The presence of calcinosis did not significantly affect survival rates in the study cohort or the SSc subset, as evidenced by no difference in median survival time between those with and without calcinosis (9.92 ± 7.5 vs. 10.5 ± 9.7, p = 0.22).
Factors associated with a higher prevalence of calcinosis in the SSc subgroup included female gender, DU, disease duration, and severe GI involvement.Previous studies have also reported a higher likelihood of calcinosis development in SSc patients with longer disease duration, typically around 7-10 years [34].In contrast, despite Muktabhant et al. suggesting a potential higher risk of early calcinosis development in elderly patients [35], our cohort did not show age-related differences.The association between DU and calcinosis aligns with prior research indicating a higher likelihood of calcinosis in patients with severe vascular digital involvement [3].An international cohort study identified additional risk factors, including osteoporosis, and reduced carbon monoxide diffusion capacity/alveolar volume [36].Recent findings by Richardson et al. demonstrated that calcinosis burden correlates with cumulative SSc-related tissue damage, irrespective of disease severity.Patients with predominantly diffuse skin disease and more severe disease features, including pulmonary hypertension, interstitial lung disease, cardiomyopathy, gastrointestinal involvement, renal crisis, myopathy, and/or tendon friction rubs, had an elevated risk of calcinosis compared to those with limited skin disease [37].Furthermore, in SSc patients, calcinosis has been linked to exposure to proton pump inhibitors (PPIs).Prolonged PPI treatment, exceeding 10 years, increased the likelihood of calcinosis at any time seven-fold and raised the odds of calcinosis cutis nearly eight-fold when compared to no PPI exposure [38].While we could not identify a definitive clinical profile of risk factors for calcinosis in our myositis patients, Fredi et al. considered anti-NXP-2 antibody as an independent predictive risk factor for calcinosis development (p = 0.024, OR 21.9, CI 95% = 1.5-319) [39].Moreover, the authors suggested that anti-NXP-2 antibody posi-tivity represents a distinct calcinosis phenotype with early onset and rapid dissemination.Two of our patients with calcinosis tested positive for anti-NXP-2 antibodies, and both were diagnosed with DM and exhibited widespread involvement from disease onset.Moreover, prior research has shown that PM/Scl antibody positivity, prolonged muscle enzyme elevation, and the use of multiple immunosuppressive therapies are associated with calcinosis development in myositis patients [40].The connection between calcinosis and anti-PM/Scl antibodies was most relevant in our cohort, and this association has been previously documented in the literature [8,41].Okada and colleagues [33] noted that alfacalcidol therapy and lupus nephritis might increase the risk of calcinosis in SLE patients.We compared alfacalcidol therapy between the calcinosis-positive and negative groups and found no significant differences.We observed only two cases of nephritis and there were no apparent abnormalities in the progression of calcinotic lesions.Another recent research study of particular interest focused on the disease course of ten lupus-related calcinosis patients.Among these patients, eight reported Raynaud's, and seven of them were anti-RNP positive.The authors suggested that lupus patients who exhibit some features resembling MCTD may be more prone to developing calcinosis [11].
In terms of internal organ involvement, the analyses centered on the SSc patient cohort, as most calcinosis cases were in this group.Univariate analysis revealed that calcinosis patients exhibited a higher proportion of severe organ involvement, particularly in vascular and GI disease.Other clinical features did not significantly correlate with the calcinosis subset in SSc, although recent research suggests a positive link between subcutaneous calcinosis at disease onset and the presence of pulmonary arterial hypertension [42].SSc patients had a higher frequency of DU history, which aligns with the proposal of a link between calcinosis and vasculopathy by Avouac et al., as their patient population with calcinosis was more likely to have a history of DU [4].Masatoshi et al. classified calcinosis as a "broad-sense" vascular lesion, proposing topical blood flow disturbance and vascular hypoxia as etiological factors [43].This hypothesis finds support in a pilot study demonstrating reduced perfusion in the superficial skin layers of calcinotic areas compared to non-calcinotic areas [44].Despite some controversy, the strongest associations with calcinosis in the univariate analysis were severe peripheral artery disease and systemic arterial hypertension.These findings are novel, lacking previous systematic investigation, though Lescoat et al. have reported an association between calcinosis and ulnar artery occlusion [45].However, clinical parameters like a history of other cardiovascular risk factors (smoking, dyslipidemia, or hyperglycemia) did not show associations with calcinosis features in univariable analyses.

Conclusions
In summary, our data have revealed various clinical associations with calcinosis across different patient populations.However, larger prospective studies are needed to confirm these preliminary findings.A definitive clinical profile of risk factors for calcinosis in IMRD patients remains elusive, with current information primarily derived from retrospective patient series.While the retrospective nature of this study may limit result interpretation, it is one of the largest studies of IMRD-related calcinosis in the literature.Further research is imperative to enhance our understanding and management of this challenging condition, which currently lacks a standardized approach and may vary in treatment outcomes based on multiple factors.

Figure 1 .
Figure 1.The anatomical distribution of calcinotic lesions across the study cohort.The extremities encompassed the elbows, knees, shoulders, buttocks, and pretibial area.Atypical areas included the spine, trunk, iliac crest, and intergluteal area.

Figure 1 .
Figure 1.The anatomical distribution of calcinotic lesions across the study cohort.The extremities encompassed the elbows, knees, shoulders, buttocks, and pretibial area.Atypical areas included the spine, trunk, iliac crest, and intergluteal area.

Table 1 .
Characteristics and prevalence of calcinosis in the studied cohort.

Table 2 .
Baseline characteristics associated with the presence of subcutaneous calcinosis in SSc patients.

Table 2 .
Baseline characteristics associated with the presence of subcutaneous calcinosis in SSc patients.

Table 3 .
Associations between dimensions of calcinosis lesions and patients' characteristics in the SSc subgroup.

Table 4 .
Binary logistic regression regarding independent predictors of calcinosis-related complications in the entire cohort.