A Chronic, Solitary Skin Ulcer Owing to Sporotrichosis

A 50-year-old woman from Ayacucho in the Peruvian highlands presented to the outpatient clinic with a 3-year history of a painless ulcerated lesion on her right knee. The patient denied prior trauma. The lesion initially appeared as a small papule, which slowly enlarged over time. On physical examination, a 5-centimeter diameter ulcer with crusting and suppuration was observed without regional adenopathy (Figure 1A).

Figure 1.

(A) Ulcerative lesion in the right knee. (B) Clinical improvement after 6 months of treatment. (C) Lactophenol cotton blue preparation showing the bouquet-like 54 arrangement of microconidia from the culture of lesion scrapings.

She was initially misdiagnosed with cutaneous leishmaniasis based on local epidemiology. Despite a negative direct Giemsa-stained smear, she received antimonial therapy on different occasions without clinical improvement.

Direct mycological examination using 10% potassium hydroxide was negative; fungal culture on peptone dextrose agar supplemented with chloramphenicol and cycloheximide was positive for Sporothrix spp. Colonies demonstrated the bouquet-like arrangement of microconidia (Figure 1C), and species identification as S. schenckii was confirmed by calmodulin gene sequencing. Treatment was started with itraconazole 200 mg daily for 6 months. Figure 1B shows the clinical improvement of the lesion after treatment, with a residual hypopigmented scar without ulceration.

Sporotrichosis is a fungal infection affecting humans and animals, and it is the most prevalent subcutaneous mycosis in Latin America.¹ In Peru, the disease is endemic, particularly in the highlands and jungle, with an area of hyperendemicity located in Abancay.² However, few studies have performed species-level identification, and all isolates reported to date have been identified as S. schenkii.³ In contrast to Brazil and other countries in the region, where S. brasiliensis has emerged as a major cause of cat-associated zoonotic transmission and has been linked to outbreaks,⁴ such transmission has not been reported in Peru. Other pathogenic species, including S. globosa, have also been reported in Latin America.¹ Although the most common clinical manifestation of sporotrichosis is lymphocutaneous spread with the development of nodules along lymphatic tracts, the disease may also present as a solitary ulcerative lesion classified as the fixed cutaneous form.⁵ Sporotrichosis should be considered in the differential diagnosis of a chronic solitary ulcerative lesion, particularly in endemic areas.