A 58-year-old male presents with a slowly progressive nodule for 6 months on the volar side of the proximal phalanx of the left fifth digit.
A nodule is located on the volar side of the proximal interphalangeal joint of the left digit, contacting the superficial side of the flexor tendon. On a lateral radiograph (Fig. 1), a nonspecific soft tissue swelling is seen, with absent calcifications. A longitudinal sonographic view (Fig. 2) demonstrates a hypoechoic lesion with Doppler signal at the periphery. On T1-weighted images (T1-WI), the lesion is isointense to muscle tissue (Fig. 3). On fat-suppressed T1-WI, the nodule is of heterogeneous signal (Fig. 4). On T2-WI, the lesion is heterogeneous with intralesional areas of intermediate and high signal intensity (Fig. 5). On fat-suppressed T2-WI, a predominant hyperintense signal is seen (Fig. 6). On T2* sequences, there is no significant blooming artefact (Fig. 7). After IV administration of gadolinium contrast, there is vivid, predominantly peripheral contrast enhancement (Fig. 8).
The resection specimen shows a whitish nodule, compatible with a gouty tophus (Fig. 9). Past history included acute gout in both first metatarsophalangeal joints, 8 years previously, for which he was treated by colchicine. His uric acid level was slightly elevated.
A gouty tophus typically represents a chronic granulomatous inflammatory response to a central core of monosodium urate crystals surrounded by a cellular and fibrovascular zone. Typically, they manifest years after an initial, acute gout arthritis, in the context of long-standing hyperuricemia [1]. De novo presentation has been described as well [1].
Macroscopically, soft tissue tophi appear as white nodules. Typical locations are the first metatarsophalangeal joint, olecranon, patella, Achilles tendon, ear and the volar side of the distal phalanges of the fingers [1,2]. Hands and wrist are often affected in advanced cases, most commonly the interphalangeal joints [2].
On conventional radiographs, gouty tophi typically have an intermediate to high density. In patients without renal insufficiency, they may calcify. When present, erosions in the adjacent bone are typically peri-articularly located, well-circumscribed with overhanging edges and parallel to the long axis of the bone. Involvement of the articular surface is a late manifestation [3]. On ultrasound, tophi have a heterogeneously hypoechogenic appearance, with peripheral increased Doppler signal [2]. Ultrasound may also depict the relationship with the adjacent tendon and osseous pressure erosions [2,4]. Gouty tophi have rather nonspecific MRI findings. They are of low to intermediate signal intensity on T1-WI and of variable signal on T2-WI, usually heterogeneously low to intermediate. They demonstrate marked enhancement [5]. Dual-energy CT can be used to detect urate crystals. This technique has a high sensitivity, but recent studies show that it has a false-positive rate of 30% in wrist arthropathies with a limited value in acute gout [6,7]. The differential diagnosis of tophaceous gout at the flexor tendons of the finger includes a giant cell tumour of the tendon, characterized by a blooming artefact on T2* sequences due to intralesional hemosiderin deposition [8]. Synovial cell sarcomas are primarily para-articularly located and contain haemorrhagic foci, being of high signal on T1-WI [9]. Melanoma should also be included in the differential diagnosis. Tendon fibroma has also a predilection for hands and feet (10).
Tophaceous gout should be included in the differential diagnosis of nodular lesions of the flexor tendon. Correlation of imaging and clinical history is the clue to the diagnosis.
Gouty tophus
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Based on the provided X-ray, ultrasound, MRI, and other imaging studies, the following key features can be observed:
1. Location and Morphology: The lesion is located near the palmar aspect (flexor tendon region) of the proximal phalanx of the fifth finger on the left hand, with a visible localized soft tissue elevation or nodular change.
2. X-ray Findings: A localized soft tissue density shadow is seen, typically medium to slightly high in density. Some patients may show calcification tendencies or superficial bone erosion. No obvious fracture signs are noted, and the trabecular structure is generally intact.
3. Ultrasound Findings: Heterogeneous hypoechoic area with abundant surrounding Doppler flow signals, indicating inflammatory or vascular proliferative response.
4. MRI Findings: On T1-weighted images, the nodule shows low to intermediate intensity. On T2-weighted images, it demonstrates heterogeneous low to intermediate signal. Significant enhancement is noted after contrast administration. It is adjacent to or exerting some pressure on the surrounding flexor tendon and soft tissue, with localized soft tissue changes.
Taking into account the patient’s age, slowly enlarging chronic nodule, and the imaging findings, the following differential diagnoses are considered:
1. Gouty Tophus (Gout Stone): Patients typically have a history of gout, elevated uric acid levels, and chronically progressive nodules which may exhibit calcification or bone erosion. On imaging, a high-density or hypointense soft tissue lesion with ring-like enhancement is often seen, and a definitive diagnosis can be made via pathological examination.
2. Giant Cell Tumor of the Tendon Sheath: Commonly found in the flexor tendon area of the fingers. On MRI T2* sequences, a “blooming artifact” may be seen. Typically, there is no history of gout in these cases.
3. Synovial Sarcoma: Very rare, often showing hemorrhagic components and high signal on T1-weighted images. Distinguishing from malignant clinical features and further pathological tests is required.
4. Fibroma of the Tendon: May appear in the hands or feet but is generally unrelated to gout or metabolic abnormalities.
5. Melanoma: Extremely rare in this region, usually presents with more obvious skin involvement; diagnosis requires skin examination and pathology.
Considering the 58-year-old male patient’s clear history of chronic gout, previously elevated serum uric acid levels, and imaging and pathological evidence of characteristic “chalky” lesions within the nodule, the most likely diagnosis is “Gouty Tophus.”
Further confirmation comes from pathological examination of the resected specimen, which shows urate crystal deposits in the center, surrounded by chronic granulomatous inflammation.
1. Treatment Strategy:
(1) Pharmacological Treatment:
• Medications to regulate uric acid levels, such as allopurinol, febuxostat, or benzbromarone, possibly combined with mild diuretics or alkalization therapy to lower serum uric acid.
• Anti-inflammatory and analgesic drugs: If necessary, use colchicine or nonsteroidal anti-inflammatory drugs (NSAIDs) to control acute inflammation.
(2) Surgical Treatment:
• In cases where local nodules significantly affect finger function or cause marked compression and limited movement, surgical removal of the gouty tophus may be considered to alleviate symptoms and prevent local tissue damage.
• Postoperative management should include laboratory monitoring of serum uric acid and coordinated medical therapy.
(3) Comprehensive Management:
• Adjust dietary habits by reducing high-purine foods, increasing fluid intake, abstaining from alcohol, and other lifestyle interventions.
2. Rehabilitation / Exercise Prescription Suggestion (FITT-VP Principle):
• F (Frequency): After surgery or once the acute phase stabilizes, perform specialized hand function exercises 3–5 times per week to restore or maintain joint flexibility and flexor tendon gliding.
• I (Intensity): In line with the degree of finger pain or swelling, begin with mild intensity (about 1–3 pounds grip strength or light resistance band). Ensure the range of motion is in the “no pain to mild discomfort” range.
• T (Time): Each exercise session lasts about 15–20 minutes, divided into shorter segments (e.g., 5–7 minutes each, followed by rest).
• T (Type): Focus on active joint mobility exercises, finger flexion and extension training, gentle grip exercises with a soft ball or light handgrip device. Avoid intense or sudden pulling forces on finger joints.
• V (Volume): Gradually increase resistance (e.g., stronger handgrip device or more repetitions) by about 10–20% per week, depending on the patient’s tolerance and rehabilitation progress.
• P (Progression): Once pain and swelling are significantly reduced, gradually intensify resistance and extend exercise duration, progressing to moderate-level grip or elastic band exercises.
Important Reminder: If local swelling recurs or if significant pain or joint inflammation develops, reduce training volume and seek medical evaluation promptly to rule out recurrence or complications. Gout patients should also closely monitor blood pressure, serum uric acid levels, and kidney function, adjusting therapy as needed.
This report is a reference analysis based on the provided medical history and imaging information. It is not a substitute for in-person consultation or the opinion of a qualified physician. Actual diagnosis and treatment should be based on the patient’s specific clinical condition and further diagnostic results.
Gouty tophus
