A 40-year-old male with end-stage kidney disease (ESKD) presented following a history of a few months of increasing painless swelling of the left hip.
An initial plain radiograph (Figure 1) showed significant heterotopic calcification overlying the left hip joint. A non-enhanced CT of the left hip (Figure 2) confirmed a large, multilobulated, periarticular calcific mass containing fluid-fluid levels. A sedimentation sign was also present (Figure 3). There was no soft tissue erosion.
An MRI of the pelvis (Figure 4) was performed, demonstrating encapsulated and well-circumscribed soft tissue masses around both hip joints together with a small amount of surrounding fluid. There was no additional soft tissue component. The masses were of homogeneous low signal intensity on T1-weighted imaging and of mixed-signal intensity on T2 weighted imaging with internal fluid-fluid levels mirroring the CT findings of sedimentation sign. Intravenous gadolinium could not be administered due to the impaired renal function.
18F-Fludeoxyglucose positron emission tomography (FDG-PET)/CT imaging was eventually performed (Figure 5), showing significant tracer uptake by the calcified masses in both hip joints.
Background
Tumoral calcinosis (TC) is a rare clinical and histopathologic syndrome characterized by calcium salt deposition in different periarticular soft tissue regions [1]. The term TC should strictly be used to refer to a disease caused by metabolic dysfunction of phosphate regulation associated with massive periarticular calcinosis [2].
Clinical Perspective
The clinical presentation depends on multiple factors including family history, renal function and the size of the masses [3]. TC typically presents as painless, firm, tumour-like masses around the joints [4]. Such mass is periarticular, is mainly located at the extensor surface of the joint, and in the anatomic distribution of a bursa. Commonly affected areas include the hip, elbow, shoulder, foot, and wrist.
Imaging Perspective
Radiographs in TC have fairly typical appearances showing multilobulated and often large foci of heterotopic calcification.
CT imaging shows calcific masses of various sizes. Fluid levels and the typical sedimentation sign are usually clearly identifiable on CT [3]. The added value of CT is the definitive exclusion of bony destruction which should not be seen in TC.
MR imaging of TC usually shows two distinct patterns. The first pattern is where the TC masses manifest as diffuse low signal intensity masses. The second pattern occasionally referred to as the bright nodular pattern, is more heterogeneous with alternating areas of high signal intensity and signal voids, sometimes seen as fluid levels. Post-contrast imaging usually shows avid enhancement of the internal septae and capsule due to a mixture of connective tissue and fibrosis [5].
Imaging of TC using FDG-PET/CT has been rarely described in the literature with only a handful of case reports existing. Similar to this case, TC masses usually show mild to moderate uptake depending on the stage of the TC mass. Our patient’s TC mass continued to increase in size over a 1-year follow-up suggesting that they were metabolically active which would fit with the increased avidity seen on FDG-PET/CT.
Bone marrow involvement is also possible and can be demonstrated as periosteal reaction on radiographs and increased radionuclide uptake at bone scintigraphy [3].
Outcome
When TC masses are asymptomatic, observation or conservative measures like physiotherapy are often used [5]. However, when the lesion is actively growing or where there is severe limitation of the joint function, surgical excision can be performed [4].
Take-Home Message / Teaching Points
Tumoral calcinosis is a benign condition occurring due to metabolic phosphate dysfunction. Correlation of the imaging findings with the clinical history of the patient is essential to rule out other differentials and correctly identify TC. FDG avidity of periarticular tumoral masses is possible and should not necessarily be attributed to a malignant process.
Tumoral calcinosis
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on the images provided by the patient (including X-ray, CT, MRI, and FDG-PET/CT), a noticeable multilobulated, mass-like high-density lesion is observed around the left hip joint. On the X-ray, multiple irregular soft tissue shadows with evident calcifications can be seen. CT shows the lesion as lobulated or clumpy calcified masses, sometimes featuring a sediment-like layered appearance (the “sedimentation sign”), with no clear evidence of surrounding bone destruction. On MRI, the lesion typically presents as predominantly low signal intensity, though some areas may exhibit mixed high and low signals with septations or cyst-like structures. After contrast enhancement, fibrous septa and capsular enhancement are often present. FDG-PET/CT reveals mild to moderate glucose metabolic activity at the lesion site, but no definite neighboring osseous erosion is noted.
Taking into account the patient’s history (chronic kidney failure/ESKD), long-term hyperphosphatemia or metabolic disturbances, and imaging findings, the most likely diagnosis is Tumoral Calcinosis.
Treatment Strategy:
Rehabilitation/Exercise Prescription Recommendations (FITT-VP Principle):
(The following plan must be tailored according to the patient’s overall health, renal function, and musculoskeletal condition.)
Disclaimer: This report is a reference analysis based on the provided imaging and clinical history, and it cannot substitute for an in-person consultation or professional medical advice. Patients should consider their own condition and adhere to the diagnoses and treatment plans recommended by specialized physicians.
Tumoral calcinosis
