Ear Sporotrichosis Mimicking Cutaneous Leishmaniasis

ABSTRACT.

Sporotrichosis is an endemic mycosis caused by Sporothrix spp. We report the case of a 30-year-old male construction worker from Jalisco, Mexico. His symptoms initiated 20 years earlier with a pustule on his left ear, which evolved into an erythematous plaque that ulcerated and progressively destroyed the surrounding cartilage. Initial treatment of presumed cutaneous leishmaniasis was ineffective. Biopsies performed revealed chronic granulomatous dermatitis, and cultures on Sabouraud medium identified Sporothrix spp. Additionally, a sporotrichin intradermal test was performed, revealing a positive result. The patient achieved complete resolution after treatment with potassium iodide (6 g per day for 4 months). He declined reconstructive surgery. Infections by Sporothrix spp. can lead to lesions that can mimic other infectious or noninfectious causes such as cutaneous leishmaniasis. It is important to consider endemic mycosis even in unusual anatomical locations such as the auricle, especially when prior treatment has failed.

INTRODUCTION

Sporotrichosis is an endemic mycosis caused by species of Sporothrix spp.¹ In Latin-America, the estimated prevalence rate ranges from 0.1% to 0.5% and most cases are reported from Brazil, Colombia, Mexico, El Salvador, Uruguay, and Venezuela. In Mexico, sporotrichosis is one of the most common subcutaneous mycoses.¹ Cutaneous leishmaniasis is also common in the aforementioned countries. In our experience, in Mexico, as in other Latin American countries, it often affects the ear.² We present a man with ulcerated fixed sporotrichosis on the ear with cartilage destruction, which was initially misdiagnosed as cutaneous leishmaniasis based on clinical presentation, epidemiology, and chronicity.

CASE REPORT

A 30-year-old construction worker from Jalisco, Mexico, presented to the dermatology clinic because of chronic ulcers on his left ear. His condition had started 20 years prior with a pustule on the helix of his left ear, which had slowly progressed to a tender erythematous plaque. The plaque had ulcerated and, during this evolution, had slowly destroyed the surrounding cartilage. He denied any contact with soil, plants, animals, or trauma. He mentioned having worked in construction in Los Angeles, California, since the age of 10.

At the onset of his illness, he was clinically diagnosed with cutaneous leishmaniasis. He did not remember the specific treatment or the time he used it for. He denied any improvement. On physical examination, he presented multiple ulcers with erythematous borders and seropurulent and bloody discharge. Extensive destruction of the helix and antihelix cartilage and few nodules were also present (Figure 1A). The wound exudate did not reveal any microorganisms on KOH examination, Ziehl-Neelsen, and periodic acid-Shiff staining. Skin biopsies from the ear for histopathological analysis and cultures were performed. The histopathological examination revealed chronic granulomatous dermatitis with the presence of neutrophils, lymphocytes, and hystiocytes (Figure 1B). After 5 days of incubation, cultures from the tissue fragments on Sabouraud medium at 26°C showed a matte white colony, exhibiting central pigmentation, a radiating pattern, and slight folding (Figure 1C). The microculture showed thin hyphae with the presence of sympodial reproduction forms compatible with Sporothrix spp. (Figure 1D). An intradermal test with sporotrichin revealed an induration of 8 mm.

Figure 1.

Macroscopic and microscopic images of ear sporotrichosis. (A) Left antihelix and helix cartilage with extensive disfigurement, accompanied by ulcers and nodules. (B) Histopathological view with hematoxylin and eosin stain showing granulomatous response with neutrophils, lymphocytes, and histiocytes. (C) Culture on Sabouraud medium at 26°C, colony with a matte white color and slightly folded. (D) Thin septate hyphae with sympodial distribution, compatible with Sporothrix spp.

A chest X-ray, complete blood count, biochemical profile, and liver function tests were normal. HIV and hepatitis testing were negative. The patient received treatment with potassium iodide 6 g for 4 months with complete resolution. He was offered reconstructive surgery, which he declined.

DISCUSSION

Sporotrichosis is an endemic mycosis with a polymorphic clinical presentation commonly acquired through traumatic inoculation with contaminated material.¹ The lymphocutaneous variety is characteristic and nearly distinctive. In Mexico, fixed cutaneous sporotrichosis is observed in 20–30% of cases, with a higher incidence in the age range of 0–15 years, primarily in men.¹ It typically affects exposed areas such as the neck and limbs. In children, the most common location is the face.³ Ear involvement is very rare,^3–5 making it a diagnostic challenge particularly in areas where leishmaniasis is also present. According to some authors, the fixed form is because of the patient’s immune response, having had repeated prior contact with the microorganism, limiting the infection at the inoculation site.¹ This is why it is associated with occupational and recreational activities, as in our patient’s case, who worked in construction at disease onset. It presents as an erythematous, infiltrated, verrucous, or nodular plaque that may ulcerate and become covered with crusts, mimicking different diseases such as cutaneous leishmaniasis, lupus vulgaris, scrofuloderma, cutaneous nocardiosis, sporotrichoid chromomycosis, and cutaneous B-cell lymphoma, among others.⁴ In our patient, the most important differential diagnosis was cutaneous leishmaniasis because of his residence in an endemic country and his ear involvement.² Sporotrichosis is usually a subacute infection with exudation, whereas leishmaniasis is usually chronic with less exudative ulcers; although, in our case, the opposite occurred.²

The clinical diagnosis of this case was a diagnostic challenge because of the evolution, location, and its atypical presentation. These characteristics may be influenced by numerous factors including the virulence of the Sporothrix strain, the anatomical site, and the patient’s immune competence. The skin’s immune system likely influences the duration and number of lesions, as well as the degree of cutaneous involvement.⁶ It is possible that the non-evolution of the fixed form to lymphocutaneous on the external ear was secondary to the ear’s multiple and variable lymphatic pathways. Lymphatic vessels arising from the upper part of the helix travel to the infra-auricular lymph node, but sometimes bypass the closest nodes.⁷ Additionally, cartilage is a highly specialized type of connective tissue that lacks nerves, lymphatic vessels, and in most cases, is avascular. A factor that may also influence this clinical presentation is the temperature of the anatomical area where the thermostability of the fungus may compromise or promote its growth. This may inhibit the growth and development of Sporothrix spp. because of an inhospitable environment when it reaches the cartilage. It has been described that an imbalanced inflammatory reaction could increase tissue destruction and worsen the disease; however, localized and less severe lesions suggest a more balanced and controlled immune response.⁶ The chronicity with recurrent ulceration and suppuration over decades ultimately resulted in the destruction and deformation of the helix and antihelix of the ear.

In Mexico, the diagnosis of sporotrichosis is mainly performed through conventional methods such as culture and identification of the etiological agent (macro and micromorphology).¹ Histopathological analysis is another alternative method.¹ Although intradermal sporotrichin testing can be used as an auxiliary diagnostic method, it is not confirmatory.⁸ In Mexico and some Latin American countries where the disease is most endemic, clinical features and a sporotrichin test may support the diagnosis, with a sensitivity of over 90%.³ Molecular tools have identified and classified new clinical species, demonstrating that this genus is a complex fungus, including Sporothrix schenckii sensu stricto, Sporothrix brasiliensis, Sporothrix globosa, and Sporothrix luriei. A nested polymerase chain reaction assay using the ribosomal RNA gene sequence as a target has high sensitivity and specificity of up to 95% and provides rapid results.^1–3,9 In our setting, this test is not readily available. The current treatment of choice for sporotrichosis is itraconazole.¹⁰ Potassium iodide is an antifungal drug included in the WHO’s list of essential medicines for developing countries. Although this drug is not a first-line treatment because of various factors, such as the lack of a standardized commercial formulation and an unclear mechanism of action, it has been proposed as a safe and effective alternative therapy for refractory sporotrichosis cases and in low-income populations where itraconazole is unaffordable. This was the case in our patient, who belonged to a population with socioeconomic barriers and limited access to specialized medical care. Terbinafine has been considered a second-line treatment.¹

Few cases of auricular sporotrichosis have been reported. Although sporotrichosis and leishmaniasis infections primarily target the skin, they affect different cellular compartments (extracellular and intracellular, respectively) and present distinct disease courses. In our patient, the uncommon location, unusual presentation, and prolonged duration led to a delay in diagnosis and appropriate treatment, increasing morbidity and resulting in partial loss of the ear. It is important to consider endemic mycosis even in unusual anatomical locations such as the auricle, especially when prior treatment has failed. Neglected tropical diseases may share similar clinical manifestations, including morphology and topography of the lesions, such as fungal or bacterial mycetoma, or, as in our case, leishmaniasis and sporotrichosis. Histopathology and cultures are necessary to accurately diagnose these cases and establish prompt effective treatment.