Dual-Energy Computed Tomography (DECT) Resolves the Diagnostic Dilemma in an Atypically Presenting Case of Gout

Gout is a common inflammatory arthropathy that presents as acute monoarthritis, most commonly of the first metatarsophalangeal (MTP) joint. Chronic polyarticular involvement may lead to confusion with other inflammatory arthropathies, including rheumatoid arthritis (RA). A thorough history, physical examination, synovial fluid analysis, and imaging are keys to establishing a correct diagnosis. Although a synovial fluid analysis remains the gold standard, the affected joints may be difficult to access by arthrocentesis. In cases where a large monosodium urate (MSU) crystal deposition is in the soft tissues - the ligaments, bursae, and tendons, it becomes a clinical impossibility. In such cases, dual-energy computed tomography (DECT) can assist in differentiating gout from other inflammatory arthropathies, including RA. Additionally, DECT can perform quantitative analysis of tophaceous deposits and, therefore, assess response to treatment.

A Rare Case of Destruction of the First Metatarsophalangeal Joint in a Patient With Gout

Gout is a crystal deposition disorder caused due to the deposition of monosodium urate crystals in joints and other tissues secondary to hyperuricemia. Podagra is the term for gout of the first metatarsophalangeal joint. In our case report, a 30-year-old male patient came to our OPD with complaints of swelling over the first metatarsophalangeal joint for one year, which was insidious in onset, localized, and had a sudden increase in size over the past three months. The patient also complained of an inability to properly wear his shoe. A plain radiograph was done, which was suggestive of an expansile lesion with the destruction of the first metatarsophalangeal joint and the erosion of the joint surface extending to the head of the first metatarsal and the proximal phalanx of the great toe. Lab investigations revealed a serum uric acid level of 10.2 mg/dl and an acid phosphatase level of 8.92 U/L. Excision of the lesion was done and a frozen section biopsy was sent intra-operatively which confirmed the presence of monosodium urate crystals. A fibular strut graft was taken to fill the defect using a square nail passing through the first metatarsophalangeal joint and a Kirschner wire was added to the interphalangeal joint to maintain the stability of the reduction. The foot was immobilized for six weeks following which the Kirschner wire was removed and range-of-motion exercises started. There was no residual deformity, and the patient responded well to the treatment.

Volumetric reduction and dissolution prediction of monosodium urate crystal during urate-lowering therapy - a study using dual-energy computed tomography

METHODS

Baseline and follow-up DECTs were performed under a standard ULT protocol. Monthly dissolution rates were calculated by simple and compound methods. Correlations with average SU were compared and analyzed. Best-fit regression model was identified. MSU dissolution times were plotted against SU at different endpoints.

RESULTS

In 29 tophaceous gout patients, MSU volume reduced from baseline 10.94 ± 10.59 cm³ to 2.87 ± 5.27 cm³ on follow-up (p = .00). Dissolution rate had a stronger correlation with SU if calculated by compound method (Pearson's correlation coefficient r= -0.77, p = .00) and was independent of baseline MSU load. The ensuing dissolution model was logarithmic and explained real-life scenarios. When SU > 0.43 mmol/l, dissolution time approached infinity. It improved to 10-19 months at SU = 0.24 mmol/l. When SU approximated zero (as with pegloticase), dissolution flattened and still took 4-8 months.

CONCLUSION

MSU dissolution is better described as a logarithmic function of SU, which explains, predicts, and facilitates understanding of the dissolution process.

Unusual Case of Gouty Arthritis of the Second Distal Interphalangeal Joint (Second Toe)

Gout is one of the most common diseases affecting men globally due to the spread of unhealthy dietary habits, kidney disease, and the use of diuretics. It is characterized as having monosodium crystals depositions in the synovial fluid, which causes an inflammatory response and painful joints. Most of the time, it can be found affecting the first metatarsophalangeal joint or other large joints in concurrence with other disorders. Non-steroidal anti-inflammatory drugs (NSAIDs), colchicine, and steroids have been known to suppress such events in most cases without the need for any surgical intervention. We present a case of a 44-years-old medically free healthy male who presented with a case of gouty arthritis in the second distal interphalangeal joint. Initially, colchicine treatment was given along with NSAIDs, but symptoms failed to subside. After a persistent increase of swelling and pain, the surgical evacuation was sought to reduce the pain and exclude any other causes of arthritis. Histopathology report confirmed the presence of monosodium urate crystals without any signs of infection. In conclusion, surgical intervention of gouty arthritis can be beneficial in cases of persistent pain and increasing rate of swelling despite the medicinal trial, especially in unusual cases of gouty arthritis such as gout of the second metatarsophalangeal joint.

An unusual location of gouty panniculitis: A case report

RATIONALE

Gouty panniculitis, characterised by the deposition of monosodium urate crystals in subcutaneous tissue, is a rare clinical manifestation of gout.

PATIENT CONCERNS

The case of a 67-year-old man is reported, who presented an erythematous nodule on the upper part of the right buttock suspicious for an abscess. This was in the context of chemotherapy for non-Hodgkin's lymphoma.

DIAGNOSES

Histopathologic examination demonstrated gouty panniculitis.

INTERVENTIONS

Because infection was suspected, an incision was performed. The lesion was found to be densely calcified and friable, without purulent discharge. Therefore, a surgical en-bloc resection was performed.

OUTCOMES

The wound healed slowly initially due to a combination of malnutrition, chemotherapy and infection. A wound infection with Enterococcus faecium was treated with antibiotic therapy (carbapenem for seven days) and local therapy. At 6-week follow up the wound showed good granulation tissue and was healing well by secondary intention. The patient was instructed to continue anti-hyperuricaemic treatment.

LESSONS SUBSECTIONS

In patients known to have long-standing hyperuricaemia and gout with nonspecific subcutaneous erythematous nodules, gouty panniculitis should be considered.

Fibrosarcoma arising from gouty tophi: report of a unique case and review of literature

Fibrosarcoma is a malignant mesenchymal tumor. To the author's best knowledge, no previous case of fibrosarcoma arising from gouty tophi has been reported. Here we reported the first case of fibrosarcoma arising from gouty tophi. A case of 58-year-old man was presented with a mass with ulcer and infection in the second joint of left middle finger for 2 months, with long standing gouty tophi. The tumor was biopsied and the biopsy showed complete excision of the tumor. With the pathological and immunohistochemical features considered, the diagnosis of fibrosarcoma associated with gouty tophi was made. The clinical findings, pathological characteristics and treatment were described.