Tenosynovitis caused by Scedosporium apiospermum infection misdiagnosed as an Alternaria species: a case report

Abstract

Background: Scedosporium apiospermum, which can usually be isolated from soil, polluted stream water and decaying vegetation, is increasingly recognized as an opportunistic dematiaceous fungus. The mortality rate of infection in immunocompromised hosts is over 50%. S. apiospermum is commonly responsible for dermal and epidermal infections (i.e., mycetoma) after traumatic penetration.

Case presentation: A 73-year-old woman was admitted to our hospital complaining of painful swelling and tenderness on the dorsum of the proximal left wrist and hand. The symptoms had persisted for approximately 2 months. A physical examination revealed a 4 x 3 cm, poorly defined, erythematous papule, which was fluctuant, with pustules and crusts on the dorsum of the left hand.

Conclusions: We report a very rare case of tenosynovitis caused by S. apiospermum infection. We identified the infectious agent via molecular DNA sequencing. The infectious agent was initially misidentified as an Alternaria species by microscopic examination with lactophenol cotton blue (LPCB) staining. The infection was successfully treated with debridement and adjuvant fluconazole therapy.

Keywords: Case report; Debridement; Scedospermum apiospermum; Tenosynovitis.

Fig. 1

a MRI T2 weighted contrast transverse image reveals diffuse edematous swelling in the dorsum of the wrist, fluid in the extensor tendon sheath and fluid collection in the distal radio-ulnar joint. b MRI T1 weighted coronal image reveals diffuse paratendinous fluid in the extensor tendon sheath. c Skin biopsy shows multiple variable-sized granulomas (arrows) bearing central microabscesses (asterisks) in the dermis. H&E staining, Scale bar measures 1 mm. d Higher magnification of the image; a boxed area shows a well-formed palisading granuloma consisting of epithelioid cells, lymphocytes and multinucleated giant cells. H&E staining, Scale bar measures 200 μm. e Silver staining demonstrates septated fungal hyphae in the granuloma. Gomori methenamine silver staining, Scale bar measures 200 μm. Inset shows a higher magnification of the fungal hyphae. Scale bar measures 50 μm. f Skin photo on the dorsum of the left hand (before treatment). g Skin photo on the dorsum of the left hand (after treatment one month later)