Cutaneous alternariosis presenting as vasculitic ulcers

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Cutaneous alternariosis is a phaeohyphomycosis caused by Alternaria species. It has a broad clinical presentation with few cases associated with diabetes. On the contrary, cutaneous vasculitis is a non-infectious inflammation and injury of the cutaneous vasculature. The treatment modalities for these two diseases are completely different. Here, we report the first case of Alternaria alternata–induced skin infection in a diabetic individual presenting in a vasculitis-like pattern. Dermatologists should recognise atypical morphologies of fungal infections in diabetic or other immunosuppressed states for accurate and early diagnosis.

A 63-year-old man presented with a 4-month history of multiple, reddish-brown, painful lesions on his legs. Cutaneous examination revealed nodules and ulcerated lesions without scales that resembled vasculitic lesions [Figure 1]. The patient was treated with cyclosporine for 1 month without any improvement. He had uncontrolled diabetes and his blood glucose level was 14.4 mmol/L (normal range: 3.9–6.1 mmol/L). A subsequent skin biopsy from a nodule revealed dermal granulomatous infiltrate with lymphocytes, neutrophils and multinucleate giant cells, with detection of fungal spores in the dermis on periodic acid-schiff stain [Figure 2]. Direct microscopic examination of the scrapped material with fluorescent staining showed club-shaped conidia [Figure 3a]. The slide mount prepared from culture demonstrated brown septate hyphae and multiple darkly pigmented ovoidal conidia muriformes in groups and branched chains [Figure 3b]. A. alternata was confirmed using a quantitative polymerase chain reaction assay. Subsequently, oral itraconazole was administered at a dose of 200 mg twice daily based on in vitro antifungal susceptibility testing using the microbroth dilution method. The patient’s lesions improved significantly after 4 months of treatment [Figure 4].

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Figure 1: Reddish nodules and ulcerated plaques on lower leg resembling vasculitis

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Figure 2: Histopathological examination showing fungal spores in the dermis (black arrows) (Periodic acid-schiff stain; bar: 500 μm).

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Figure 3a: Direct microscopic examination with fluorescent staining of the scrapped material revealed club-shaped conidia (400x).

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Figure 3b: Fungal tissue culture with lactophenol cotton blue mount showing brown septate hyphae and multiple darkly pigmented, ovoidal conidia muriformes (400x).

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Figure 4: Significant improvement four months after treatment.

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Alternaria species are well-known soil saprophytes and plant pathogens.^1–3 Cutaneous alternariosis is a phaeohyphomycotic infection caused by Alternaria species with a broad spectrum of clinical presentations. The predisposing factors include immunosuppression, local wounds, or systemic diseases, such as diabetes. The clinical presentations include papulonodules, plaques, ulceration, subcutaneous nodules, or bullous lesions.^3–5 Erythema and papulonodules are the common clinical manifestations of cutaneous alternariosis.¹

However, necrotising vasculitis-like patterns in cutaneous alternariosis have not yet been reported. In the present case, the decreased immunologic state state caused by diabetes mellitus weakened the resistance to fungal invasion. Itraconazole was effective in improving the patient’s lesions as in other reported clinical presentations of cutaneous alternariosis.

Skin disorders affect about one-third of patients with diabetes mellitus. The prevalence of pruritus and xerosis in diabetic subjects is significantly higher than that in age-matched non-diabetic subjects, especially in the lower limbs.² The changes in the immunological state in diabetic patients accompanied by pruritus with skin micro trauma increases the opportunity for fungal infection. Under these conditions, the Alternaria species can invade via cutaneous abrasions to cause skin infection.

We report a case of cutaneous alternariosis mimicking cutaneous vasculitis. The microabrasions caused due to frequent scratching on the legs in an immunocompromised diabetic patient may have been the portal of entry for the fungus leading to skin lesions resembling vasculitis, that were confirmed on histopathology and microbiological assessment.