Scedosporium apiospermum skin infection mimicking tuberous xanthoma

Authors


Kozo Yoneda, M.D., Ph.D., Department of Dermatology, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Kitagun Mikicho, Kagawa 761-0793, Japan. Email: kyoneda@med.kagawa-u.ac.jp

Dear Editor,

Deep fungal infections are caused by a large and heterogeneous spectrum of molds, mainly Aspergillus, Fusarium or Scedosporium species. Scedosporium apiospermum, the asexual form of the ascomycete fungi, Pseudollescheria boydii, is a saprophyte mold found in soils, polluted water and sewage all over the world.1,2 These fungi can also present as an opportunistic pathogen involving skin, lung, bone or eye. Although this microorganism has low inherent virulence, it can elicit infections as a fungal opportunist. This pathogen is being increasingly recognized as an opportunistic infection and currently accounts for approximately 20% of all non-Aspergillus mold infections. In the past several years, an increasing number of human cases have been reported due to widespread usage of immunosuppressive drugs. Among them, cutaneous and pulmonary forms are sometimes reported. We herein describe S. apiospermum skin infection in a patient with lung carcinoma. The lesion was very similar to tuberous xanthoma. As far as we know, this is the first case showing that the lesion looked like tuberous xanthoma.

The patient was a 75-year-old Japanese man diagnosed in July 2009 as having stage III lung squamous cell carcinoma. Radiation therapy was begun in August. After radiation therapy, he was treated with docetaxel and carboplatin (one cycle) and complete response was achieved. Then, surgical excision was performed in November 2009. Radiation pneumonitis was observed in December 2009. Oral prednisolone (20 mg/day) was initiated. Pneumothorax of the right lung occurred in January 2010. There was no special therapy performed for pneumothorax at this time. Pneumothorax resolved within 1 month without any treatment. However, pneumothorax recurred in June 2010 and drainage was performed to treat the second episode.

On 8 June 2010, a subcutaneous nodule appeared abruptly on the dorsal aspect of the metacarpophalangeal joint of the left hand (Fig. 1a,b). The lesion was a asymptomatic, the color was brownish yellow and it looked like tuberous xanthoma, although it was soft and appeared suddenly without any previous sign. There was no hypercholesterolemia at that time. Skin biopsy specimen was obtained from this nodule. A hematoxylin–eosin-stained section showed cellular infiltrates containing histiocytes, neutrophils and multinucleated giant cells within the deep dermis to the subcutaneous tissue (Fig. 1c,d). Fibrin deposits and necrotic tissues were observed. Periodic acid Schiff staining of the biopsy specimen demonstrated fungal elements within the deep dermis (Fig. 1e,f). Fungal culture grew colonies on both blood agar and potato dextrose agar (Fig. 1g,h). Polymerase chain reaction (PCR) targeting the internal transcribed spacer (ITS)1, 5.8S ribosomal DNA and ITS2 of the isolated fungus was carried out according to the previously described method.3,4 Amplified PCR products of approximately 500 bp were subsequently sequenced and subjected to a basic local alignment search tool (BLAST) search in the GenBank sequence database. The sequences were identical to the corresponding sequences of S. apiospermum. The patient was started on therapy with voriconazole (400 mg/day), and his skin lesion slowly resolved over the next 2 months.4–6 However, he died on 21 August due to hemoptysis.

Figure 1.

 (a,b) Nodule was observed on the dorsal side of the metacarpophalangeal joint of the left hand. This nodule was asymptomatic and the overlying skin appeared to be brownish yellow. (c,d) A hematoxylin–eosin-stained section showed cellular infiltrates containing histiocytes, neutrophils and multinucleated giant cells within the deep dermis to the subcutaneous tissue. Epithelioid cells demonstrated elongated, pale eosinophilic cytoplasm and central, ovoid nuclei. (e,f) Periodic acid Schiff staining demonstrated fungal elements in the dermis. (g,h) Fungal culture grew colonies on both blood agar and potato dextrose agar. (Scale bars: [c,e] 360 μm; [d] 35 μm; [f] 15 μm.)

The incidence of unusual opportunistic fungal infection, such as S. apiospermum, has been increasing because of the broad usage of corticosteroids, immunosuppressants, antineoplastic agents and broad-spectrum antibiotics in recent years.1,2 Cutaneous scedosporiosis usually presents as hyalohyphomycosis and includes mycetoma with white grains, sporotrichoid ascending soft tissue infections and deep tissue infections with or without osteomyelitis. We could not observe sporotrichoid ascending or disseminated infection in our case. Instead, the lesion looked like tuberous xanthoma. Unlike xanthoma, the lesion developed very quickly and did not demonstrate an erythematous halo.

Ancillary