Dermatology Online Journal

A case of cutaneous protothecosis in a polyarteritis nodosa patient and review of cases reported in Japan
Chie Okazaki^1,2, Chihiro Wakusawa³, Rika Chikama³, Kazuhiro Murakami⁴, Hideaki Hitomi⁵, Kazuo Satoh⁶, Koichi Makimura⁶, Masataro Hiruma^1,2
Dermatology Online Journal 17 (9): 2

1. Department of Dermatology and Allergology, Juntendo University Nerima Hospital
2. Department of Pharmasy, Juntendo University Nerima Hospital
3. Department of Dermatology, Tohoku Kouseinenkin Hospital
4. Department of Clinical Pathology, Tohoku Kouseinenkin Hospital
5. Department of Pulmonology, Tohoku Kouseinenkin Hospital
6. Institute of Medical Mycology and Genome Research Center, Teikyo University

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Abstract

A 76-year-old woman farmer with a 20-year history of oral steroid treatment for polyarteritis nodosa, noted a rash consisting of numerous small papules on the dorsum of her right hand in February 2007. The rash worsened over time, and in April 2008 red papules and pustules as big as grains of rice fused to form plaques extending up her arm from the dorsum of the right hand to the extensor surface of the forearm. The plaques were accompanied by erosions, ulcers, and crusts. Skin biopsy specimens from the dorsum of the right hand showed a dense cell infiltration in the upper to middle layer of the dermis, with numerous morula-like microorganisms within the cells. Cultures of the specimens on Sabouraud dextrose agar produced creamy, yeast-like colonies. The colonies produced sporangia, with cells of varying sizes arranged in the pattern of a spoked-wheel. The microorganisms were identified as Prototheca wickerhamii on the basis of their morphological characteristics, sugar assimilation patterns, and molecular biological techniques. Treatment with amphotericin B was planned, but the patient died from respiratory failure before initiating treatment. We review the characteristics of the cutaneous protothecosis cases reported to date in Japan.

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Introduction

Protothecosis is an extremely rare infection caused by Prototheca species, which are categorized as achloric algae [1]. In most cases, the underlying condition associated with the infection is immunocompromise, either local or systemic [2]. Here we report a case of cutaneous protothecosis in a Japanese patient with polyarteritis nodosa and summarize the characteristics of cases reported to date in Japan.

Case Report

The patient was a 76-year-old woman farmer who had received oral treatment with prednisolone, 15 mg per day, for polyarteritis nodosa since 1988; the treatment was ongoing when we first examined her. From 1997 onward, she was repeatedly hospitalized for interstitial pneumonia. Beginning in 2006, she received prophylactic treatment with itraconazole, 50 mg daily, for chronic respiratory failure. The patient’s history of treatment for protothecosis began in February 2007, when numerous small papules appeared on the dorsum of her right hand. She was initially examined at the dermatology department of the Tohoku Kouseinenkin Hospital in March 2007. Skin biopsies of specimens from the right hand revealed numerous microorganism elements in the dermis that had positive periodic acid-Schiff (PAS) staining. However, because the specimens were both bacterial culture negative and fungal culture negative, a confirmed diagnosis could not be made. A decision was therefore made to increase the dosage of itraconazole to 100 mg per day and continue to monitor the patient. In March 2008, the patient was readmitted to the hospital’s department of internal medicine for pneumonia; at that time her rash was reexamined.

Figure 1a	Figure 1b
Figures 1a and 1b. In April 2008, the patient presented with red papules and pustules, some as big as grains of rice, which had aggregated and fused to form plaques that dotted her arm from the dorsum of the right hand (a) to the extensor surface of the forearm (b).

In April 2008, she presented with red papules and pustules, some as big as grains of rice, which had aggregated and fused to form plaques that dotted her arm from the dorsum of the right hand (Figure 1a) to the extensor surface of the forearm (Figure 1b). Some plaques were accompanied by erosions and crusts. On the extensor surface of the forearm, the lesions were irregularly shaped or formed moth-eaten-like and shallow ulcers. We initially suspected cryptococcosis or other deep cutaneous mycoses.

The skin biopsy specimens were submitted for histopathological examination, hematoxylin and eosin (HE) stains revealed dense inflammatory cell infiltration from the upper to middle layer of the dermis. The high-powered field image showed many inflammatory cells with faintly stained spherical or morula-like fungal elements inside. High-magnification PAS stains showed structures consistent with Prototheca organisms (Figure 2).

Figure 2	Figure 3
Figure 2. The skin biopsy specimens stained with hematoxylin and eosin (HE) revealed dense inflammatory cell infiltration from the upper to middle layer of the dermis. The high-powered field image showed many inflammatory cells with faintly stained spherical or morula-like fungal elements inside. Figure 3. Parker-KOH preparation of crusts from skin lesions revealed large numbers of spherical or morula-like sporangia deeply stained with Parker ink spoked-wheels.

In the microbiological tests, Parker-KOH preparation of crusts from skin lesions revealed large numbers of spherical or morula-like sporangia deeply stained with Parker ink (Figure 3). The creamy yeast-like colonies were cultured on Sabouraud dextrose agar at 25°C for 6 days. Microscopic examination of these colonies showed that the cell size of the microorganisms varied from large to small. Within the cells, the spherical sporangia could be seen, each containing 2 to 20 endospores arranged like spoked wheels.

The isolate was identified as Prototheca wickerhamii based on the assimilation test with API 20C AUX (SYSMEX bioMérieux Co., Ltd., Tokyo) and nuclear DNA base sequence analysis of 28SrDNA (D1/D2) region [3]. Antifungal susceptibility was tested according to the standardized method by the Clinical and Laboratory Standards Institute [4]. The MICs values (μg/ml) were as follows: micafungin, >16; amphotericin B, 1; flucytosine, >64; fluconazole, >64; itraconazole, 4; voriconazole, 2; miconazole, 16. Treatment with amphotericin B was planned, but the patient’s respiratory symptoms worsened around the time the condition was diagnosed and she passed away of chronic respiratory failure.

Discussion

Protothecosis is an extremely rare disease caused by infection with Prototheca spp., which belong to the category of achloric algae. Prototheca are ubiquitous in nature, occurring in such environments as the slime flux of trees, water, soil, and the viscera of fish [1]. They infect by traumatic inoculation into subcutaneous tissues. Although Prototheca are widely found in nature, few cases of protothecosis have been reported worldwide (approximately 100 cases) [5]. Abnormalities in the immune status of the host are thought to be involved in the development of this disease. Although Prototheca is not a fungus, the disease is usually treated within the field of mycology.

In terms of disease type, protothecosis can be divided into three categories: cutaneous-subcutaneous, olecranon bursitis, and systemic-disseminated. The cases reported in Japan consist of 26 cases of cutaneous-subcutaneous, no cases of olecranon bursitis, and 3 cases of systemic-disseminated.

The reported cases of cutaneous protothecosis in Japan consist of patients ranging in age from 42 to 80 (average of 66.8 years), with a slightly higher prevalence in men than in women (15 males, 11 females). Cutaneous manifestations included papules, plaques, scales, pustules, crusts, and erosions. Exposed areas such as the dorsa of the hands and the forearms accounted for almost all of the cases. The most frequent site of infection was the upper limbs, with 17 cases (61.5%). Other sites were the lower limbs (7 cases), the face (4 cases), and the trunk (3 cases). In 4 cases, infection occurred in two sites.

In 15 cases, the patient suffered from an underlying systemic disease such as diabetes mellitus, rheumatoid arthritis, or nephrotic syndrome. In 9 cases, patients had either systemic disease that was being treated with oral corticosteroids and immunosuppressant drugs, or local disease that was being treated with topical steroids. In 16 cases the pathogen was P. wickerhamii; in the remaining cases another species of Prototheca was the infectious agent.

To make a diagnosis of protothecosis, it is necessary to confirm the presence of Prototheca organisms histopathologically and then isolate and identify the causal microorganism [6]. If the characteristic morula-like structure containing multiple endospores can be confirmed histopathologically, then the diagnosis becomes easy. In the case described here, the presence of endospores was successfully confirmed by HE stain, but the diagnosis was delayed by the fact that this disease is unfamiliar to dermatologists. We believe that earlier diagnosis of protothecosis would have been possible had we been more familiar with this disease.

For treatment, azole antifungals such as itraconazole and fluconazole are generally used [7 ,8, 9]. In the case of a solitary lesion, surgical excision is recommended. In the case described here, oral administration of itraconazole had been ineffective. We had planned to treat the patient with liposomal amphotericin B, but the patient expired because of worsening of the primary disease before the treatment could be initiated.

ACKNOWLEDGMENTS: This study was partly funded by Health, Labour and Welfair Sciences Research Grants for Research on Measures for Intractable Diseases (H22 shinko-ippan 008) from the Japanese Government.

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