症例報告 2
A Young Man with Axial Spondyloarthritis-like Symptoms Likely Induced by Monosodium Urate Deposition on the Upper Thoracic Vertebrae
2025 年 49 巻 2 号 p. 151-158
詳細
2025 年 49 巻 2 号 p. 151-158
Spinal gout is a rare clinical presentation of gout; its diagnosis is challenging. Dual-energy CT (DECT) enables the detection of monosodium urate (MSU) deposition in the spine as well as in the extremities. A young man with hyperuricemia and no history of gout complained of pain around his sternum, which worsened during work. DECT revealed significant MSU deposition around his first thoracic vertebra as compared to the spine of a patient with severe hyperuricemia, as well as multiple tophi in the extremities. His hyperuricemia was caused by a decrease in the urinary excretion of uric acid. The patient was then treated with a selective urate resorption inhibitor (SURI), dotinurad. His serum uric acid level was within normal limits, and MSU deposition was reduced as observed on DECT images after six months. Treatment with the SURI reduced MSU deposition in the vertebrae, as confirmed on DECT images, as well as serum uric acid levels.
Gout is a crystal-induced inflammatory articular disease caused by the deposition of monosodium urate crystals in the joints due to hyperuricemia1). As the solubility of urate depends on temperature, monosodium urate is deposited in the extremities as they are at a lower temperature than the core of the body2). Spinal gout is a rare presentation of monosodium urate deposition that causes backache of an apparently unknown origin and sometimes leg paralysis due to nerve root damage when they are compressed by tophi3,4). However, the diagnosis of spinal gout is challenging because erosions on lumbar radiographs, draining sterile pus, and the detection of tophi through surgical resection are possible clues to the diagnosis. Recent advances in dual-energy computed tomography (CT) have revealed symptomatic or asymptomatic monosodium urate deposition not only in the joints but also in the extra-articular areas, including spinal lesions5). We treated a young male patient with chest pain caused by costal and spinal lesions due to monosodium urate deposition detected using dual-energy CT images.
Case: A 24-year-old man
Chief Complaint: Chest pain on and around the sternum induced by trunk extension
Clinical Course: A 24-year-old man complained of chest pain on and around his sternum caused by trunk extension that persisted for several months and was resistant to analgesics, such as NSAIDs and weak opioids, at his orthopedic clinic. Chest magnetic resonance imaging (MRI) at the clinic showed non-specific T2-high and T1-low areas at the upper part of the sternal body, suggesting post-traumatic changes, but no other findings were observed, including fluid collection in joint spaces, fractures, and muscle damage resulting in pain. The patient was referred to our hospital due to possible spondyloarthropathy and sternoclavicular arthritis. The patient was 176 cm tall, weighed 70 kg, and had a body mass index of 22.6. The patient did not consume alcohol or smoke regularly. His medical history included tonsillectomy for adenoid hyperplasia in childhood and no other diseases, such as skin lesions, dental issues, gout, or hyperuricemia. He had no remarkable family history of similar conditions or hyperuricemia. The pain was sharp, momentary, and brief and worsened with trunk extension, effort, and coughing, which interfered with his construction work. However, no chest pain was observed at rest or during sleep. The pain did not worsen upon waking or improve with movement, unlike typical symptoms of ankylosing spondylitis. His symptoms did not include optical, pharyngeal, or mucocutaneous disturbances, abdominal pain, bloody diarrhea, or backache in the sacroiliac area, which can indicate axial spondyloarthropathies. Upon examination, no swelling or tenderness was noted in his sternoclavicular joints, which is often observed in patients with pustulotic arthroosteitis. Blood tests revealed hyperuricemia (serum uric acid 8.8 mg/dL), normal renal function (eGFR 91.9 mL/min/1.73 m2), and decreased fractional excretion of uric acid (FEUA 4.66%, Table 1). The antinuclear antibody, rheumatoid factor, and anti-cyclic citrullinated peptide antibody were all negative. Thus, we hypothesized that monosodium urate (MSU) was deposited in the joints of the patient’s chest and upper spine. Dual-energy computed tomography (DECT) showed MSU deposition in the sternocostal and facet joints, intervertebral discs, and their adjacent areas, as well as in the anterior longitudinal ligament of the first and second thoracic vertebrae (Figure 1). No fracture, pleuritis, pericardial effusion, lymphadenopathy, or lung lesions were observed. Compared with DECT images of the same planes of a gout patient with multiple tophi in the hands and feet due to poorly controlled hyperuricemia without any pain in his trunk, the DECT images of this patient suggested that the findings of MSU deposition were associated with his thoracic symptoms.
Subsequently, a selective urate transporter inhibitor, dotinurad, was administered to the patient, and the serum uric acid level was efficiently decreased by elevated FEUA (Figure 2). As shown in Figure 1, DECT images at three months and six months later showed decreased MSU deposition compared to those at diagnosis. Initially, he had taken nonsteroidal anti-inflammatory drugs to reduce chest pain, but he needed no more them two weeks after the start of dotinurad. Colchicine was concomitantly administered for three months. He continued his work without any pain or discomfort in his trunk after taking only 2 mg of dotinurad. Laboratory data eight months after onset revealed well-controlled hyperuricemia (serum uric acid 2.8 mg/dL, FEUA 25.92%; Figure 2).
| Bil-T | 0.6 | mg/dL | WBC | 5.9 | x103/μL |
| r-GT | 21 | U/L | RBC | 5.80 | x106/μL |
| ALP | 95 | U/L | Hgb | 16 | g/dL |
| AST | 20 | U/L | Hct | 46.6 | % |
| ALT | 41 | U/L | PLT | 273 | x103/μL |
| LD | 173 | U/L | PT | 108 | % |
| ChE | 444 | U/L | APTT | 28 | sec |
| ALB | 4.9 | g/dL | Fibrinogen | 285 | mg/dL |
| TP | 7.8 | g/dL | D dimer | <0.5 | μg/mL |
| Na | 141 | mEq/L | RF | <4 | IU/mL |
| K | 4.1 | mEq/L | ANA | (ー) | |
| Cl | 104 | mEq/L | anti-CCP Ab | <0.5 | U/mL |
| Ca | 10 | mg/dL | anti-SS-A Ab | <1.0 | U/mL |
| iP | 3 | mg/dL | sIL-2R | 156 | U/mL |
| UN | 5.9 | mg/dL | Urine | ||
| Cr | 0.86 | mg/dL | glucose | (ー) | |
| eGFR | 91.9 | mL/min/1.73m2 | protein | (ー) | |
| UA | 8.8 | mg/dL | bilirubin | (ー) | |
| AMY | 58 | U/L | PH | 8 | |
| CK | 110 | U/L | ketone body | (ー) | |
| glucose | 94 | mg/dL | occult blood | (ー) | |
| CRP | 0.11 | mg/dL | nitrite | (ー) | |
| IgG | 1155 | mg/dL | WBC | (ー) | |
| CH50 | 45.5 | U/mL | FEUA | 4.66 | % |
| U-Cr | 107.4 | mg/dl | |||
| U-UA | 50.1 | mg/dl |
ANA, antinuclear antibody; RF, rheumatoid factor; FEUA, fractional excretion of uric acid; occ: (urinary) occult blood.
Arrowheads indicate prominent urate depositions at onset and in the same area 3 and 6 months later compared to the same locations in the reference images.
sUA: serum uric acid (mg/dl), FEUA: fractional excretion of uric acid (%)
The diagnosis of diseases associated with musculoskeletal pain in the trunk is challenging. Young men who experience chest discomfort or pain upon chest expansion are generally assumed to have ankylosing spondylitis or other axial spondyloarthropathies related to uveitis and inflammatory bowel disease. However, this patient’s chest pain was aggravated while working and did not worsen in the morning or at rest, thereby being clinically less suggestive of such axial spondyloarthropathies. In contrast, he showed primary hyperuricemia without overweight, metabolic syndrome, diabetes, heavy alcohol consumption, or a dietary predisposition to increased serum uric acid levels. Because he was a construction worker, the high muscle volume indicated by the pectoralis major on the CT images was associated with hyperuricemia, although he did not work out excessively or consume a high-protein diet to build up his muscles for special purposes. In this case, decreased urinary uric acid excretion was thought to be a major cause of hyperuricemia that induced urate deposition in the spinal lesions. Therefore, a selective urate reabsorption inhibitor could decrease serum uric acid levels and spinal urate deposition, providing relief from chest and back pain.
The pitfalls of using DECT for gout includes detection of artifacts in the nail bed, skin, and arteries, as well as those caused by motion6). Linear and stippled forms may be artifacts compared to angular (irregularly shaped) and oval shapes that represent tophi in DECT images. Thus, in this case, the DECT images of the spine were compared with those of patients with uncontrolled hyperuricemia and peripheral tophi to reduce the risk of false-positive MSU deposition. Moreover, linear or stippled forms on the surface of the skin or bones were recognized as artifacts.
The patient was diagnosed with spinal and sternocostal gout, without peripheral arthritis. A majority of patients with spinal gout have a history of gout (59.2%7), 86%8)). Spinal MSU deposition is observed in 34% of patients with gout and is not always symptomatic5). Spinal deposition volume of MSU in patients with gout was found to be significantly higher than that in the control group5). Serum uric acid levels and erythrocyte sedimentation rate values were positively correlated with spinal MSU volume5). In contrast, spinal urate deposition was independent of the severity of backache and the presence of tophi5). Therefore, spinal urate deposition may not be associated with symptoms and may occur independently of peripheral gout.
Table 2 shows previously reported case series and the current case concerning spinal gout diagnosed using DECT. Eleven reports showed positive MSU deposits in DECT images of the spine. The mean age was 47 years, and eleven of the patients, including our patient, were male. The mean serum uric acid level at the diagnosis was 8.2 mg/dL. Six patients reported a history of gout. Ten patients had lumbar pain. Neurological symptoms due to spinal cord or root compression occurred in three patients. No other patients reported a chief complaint of chest pain. MSU deposits were mainly found in the lumbar and sacroiliac joints. Three patients had upper vertebral lesions: one with lesions in the thoracic joint and two with lesions in the cervical joint, similar to the patient in this case. Surgical treatment was performed in one patient for the pathological confirmation followed by urate-lowering therapy (ULT). The others were treated with NSAID, glucocorticoid, and colchicine together with ULT. A follow-up DECT was not included in the case series to confirm the volume reduction of MSU deposition. Therefore, this case report is of considerable importance in terms of the efficacy of the selective uric acid transporter inhibitor in reducing MSU deposition on and around the spine and ameliorating the sternocostal pain.
In conclusion, spinal gout is a differential diagnosis in patients with chest and back pain of unknown etiology, and DECT may help diagnose this condition without invasive approaches.
| Reference | age | gender | sUA | Cr | gout history | symptoms | DECT images | treatment |
| 9) | 51 | male | 1.9 | 1.48 | Y | neck pain | costovertebral deposition of MSU in Th1/2 | colchicine |
| 10) | 43 | male | NA | NA | NA | fever, low backache | L4/5, L5/S1 interspinous ligaments, L4 facet joint | glucocorticoid |
| 11) | 62 | female | 9.5 | 1.02 | N | acute low backache, no neurological symptoms | sacrum, transverse processes, bilateral iliac wings | glucocorticoid, colchicine, ULT |
| 12) | 67 | male | NA | NA | NA | backaches | L5-S1 | no data available |
| 13) | 54 | male | NA | NA | Y | axial pain, myeloradicular pain | L4/5 facet joint | no data available |
| 14) | 43 | male | 11.0 | NA | Y | backache | L4/5 facet joint, L4/5 interspinous ligament, bilateral sacriliac joints, left hip joint | only symptomatic relief, no surgery |
| 15) | 49 | male | NA | NA | NA | quadripharesis | C1-2, cervical cord compression | death before surgery |
| 16) | 39 | male | 6.2 | NA | Y | generalized weakness, chronic systemic pain, draining pus from the left foot, root compression | L3-S1, L4/5, L5/S1, S1/2 | ULT+PSL5mg |
| 17) | 67 | male | 9.2 | NA | Y | backache | L5, S1, hands, elbows, feet, knees | ULT+Col |
| 18) | 29 | male | 9.4 | 1.72 | N | back ache | dissapearance of L5,S1 facet joints | surgery, ULT |
| 19) | 35 | male | 10.0 | 1.21 | Y | back ache | L1,2,3,5,S1 | glucocorticoid, ULT |
| current case | 24 | male | 8.4 | 0.86 | N | chest pain | 1st sternocostal joint, Th1,2 transverse process, zygapophyseal joints, anterior longitudinal ligament | ULT+NSAID |
NA, not available; C, cervical vertebra; T, thoracic vertebra; L, lumbar vertebra; S, sacrum; ULT, urate-lowering therapy; Col, colchicine; MSU, monosodium urate; PSL, prednisolone; NSAIDs, nonsteroidal anti-inflammatory drugs
We would like to thank Editage (www.editage.com) for English language editing.
Hiroshi Kataoka received speaker’s fees from Mochida Pharmaceutical Co., Ltd.
All other authors declare that they have no conflicts of interest.
The authors obtained written consent from the patient.
