INTRODUCTION

Gout is a chronic disease in which monosodium urate crystals are deposited in joints and tissues. Gouty tophi are thought more likely to be formed with higher uric acid values and longer periods of poor uric acid control, frequently occurring in the fingers, toes, knees, elbows, and heels. Ulceration of gouty nodules is relatively uncommon and resistant to treatment. Here, we report two cases of ulcerative gouty tophus on the toes, neither of which were diagnosed as hyperuricemia until they were referred to us.

CASE REPORTS

Case 1: A 92-year-old Japanese female was referred to our affiliated hospital due to a skin ulcer on her toe that had not improved with washing and antibiotics treatment for several months. She had hypertension, chronic renal failure, and heart failure and had never been diagnosed with gout. A physical examination revealed a 2.0 × 2.0 cm skin ulcer covered with red granulation tissue on the third toe of the left foot, and white deposits were observed at the bottom of the ulcer (Fig. 1a). A biopsy was taken, and a white chalky substance was discharged from the wound at the time of incision. Histopathology showed nodules composed of amorphous materials with needle-like crystals in the dermis. Lymphocytes, neutrophils, and histiocytes were observed around the nodules (Fig. 1b). In addition, multiple subcutaneous nodules were observed on the lateral fingers and toes, ranging from 1 to 1.5 cm in diameter. These nodules were firm, mobile, and non-tender. Blood tests showed high levels of serum uric acid (9.7 mg/dL) and creatinine (1.75 mg/dL). Allopurinol administration was initiated, and the serum uric acid value fell to 6.9 mg/dL after four months. The skin ulcer was treated topically and epithelialized without further deterioration.

Figure 1: (a) Clinical features of case 1.(b) Histopathological features of case 1 (200×).

Case 2: A 70-year-old Japanese male complained of a nodule on the second toe of the right foot, which appeared two years previously. A physical examination showed a 5-mm nodule with a small ulcer and crusts (Fig. 2a). A biopsy revealed amorphous material deposits in the dermis, surrounded by palisaded histiocytes and mononuclear cells (Fig. 2b). The patient had not previously been diagnosed with hyperuricemia; however, a laboratory examination showed increased uric acid (7.8 mg/dL). Liver and renal functions were normal. Treatment for gout was started with an oral antipodagric drug, and the ulcer of the gouty nodule was treated with topical antibiotics.

Figure 2: (a) Clinical features of case 2. (b) Histopathological features of case 2 (100×).

DISCUSSION

The prevalence of gout has been reported to range between 0.68% and 3.90% in adults [1]. Gout is more common in men than women, with a male-to-female ratio of 8:1 in the Asian population. The present cases developed ulcerative gouty tophus, and gout was identified in both cases. In case 1, a biopsy was performed under suspicion of squamous cell carcinoma, due to the presence of a persistent ulcerative nodule. A gouty nodule was revealed by histopathological examination. While the precise timing of the patient’s gout onset was unknown, it was presumed that long-term complications of hypertension and chronic renal failure exacerbated her hyperuricemia. In case 2, although the patient showed no signs of hyperuricemia, the unique clinical appearance and histopathological features of gout led to its diagnosis. Ulceration in gout is relatively rare [2–7], and ulcerative gouty tophi are resistant to conventional therapies, resulting in chronic wounds. Various treatments, including topical wound care and surgical treatment (curettage, debridement, and skin graft), are utilized for ulcerative gouty tophi [5–7]. Early detection of gouty nodules is essential to prevent refractory conditions against treatment if they are overlooked.

REFERENCES

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3. Pradhan S, Sinha R, Sharma P, Sinha U. Atypical cutaneous presentation of chronic tophaceous gout:A case report. Indian Dermatol Online J. 2020;11:235-8.

4. Zahoor H, Patel R, El-bahri J. Ulcerated tophaceous gout. Cureus. 2022;14:28729.

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