Pityriasis versicolor with a unique clinical appearance

Medical Mycology 1998, 36, 331–344 Accepted 21 May 1998 Case Report Pityriasis versicolor with a unique clinical appearance C. OKUDA,∗ M. ITO,† W. NAKA,‡ T. NISHIKAWA,‡ H. TANUMA,§ H. KUME,¶ M. HOTCHI∗∗ & G. MIDGLEY†† ∗Section of Dermatology, Saiseikai Sanjo Hospital, Sanjo; †Department of Dermatology, Niigata University School of Medicine, Niigata; ‡Department of Dermatology, Keio University School of Medicine, Tokyo; §Departments of Dermatology and ¶Pathology, Kitasato University School of Medicine, Sagamihara; ∗∗Department of Pathology, Shinshu University School of Medicine, Matsumoto, Japan; and ††Department of Medical Mycology, St John’s Institute of Dermatology, St Thomas’s Hospital, London, UK We experienced an atypical case of pityriasis versicolor with a unique clinical appearance and undescribed mycological features. Although Malassezia sp. was cultured from the keratotic material, the fungal elements observed in the material were not readily identified as Malassezia. The diagnosis was established with the aid of immunohistochemical and ultrastructural studies with the aetiological agent being identified as M. globosa. Keywords Malassezia, Malassezia globosa, pityriasis versicolor Introduction Pityriasis versicolor is a superficial fungus infection caused by Malassezia furfur. Clinically, macular, erythematous, pigmented or hypopigmented lesions with fine scaling are present [1]. The diagnosis of this disease is established by detection of the pathognomonic fungal elements in a KOH preparation of skin scrapings [1]. The present paper describes an atypical case of pityriasis versicolor with a unique clinical appearance as well as undescribed mycological features of the fungus. thickening, partially with keratotic plugs in hair follicular pores (Fig. 2a), and contained numerous yeast cells and hyphae which were basophilic. The epidermis, except for the horny layer, showed no particular pathological findings. In the upper dermis, infiltration of a few mononuclear cells was seen. By methenamine–silver nitrate stain, many globose to subglobose fungal cells Case report A 62-year-old Japanese female received cholecystectomy and noticed yellow-brown macular lesions on her chest. Four, well-demarcated, hyperkeratotic, unevenly yellow to brown-coloured, small macular exanthemas were observed on the middle part of her chest (Fig. 1). There was no subjective symptom. Histopathological examinations The hyperkeratotic skin lesion was biopsied. By haematoxylin–eosin stain, the horny layer showed marked Correspondence: Chozaburo Okuda MD, Section of Dermatology, Saiseikai Sanjo Hospital, Sanjo 955-8511, Japan. Fax. 0256-34-7541.  1998 ISHAM Fig. 1 Clinical appearance. Well-demarcated, hyperkeratotic, macular exanthemas are observed on the chest. 332 Okuda et al. Fig. 2 Histological findings. (a) Horny layer shows marked thickening (haematoxylin–eosin stain, ×18). (b) Many globose fungal cells of varying sizes and septate hyphae are seen among the horny cells in the entire horny layer (methenamine–silver nitrate stain, ×700). Fig. 3 A great number of fungal elements in the keratotic material from the lesion, in KOH and Parker ink preparation. (a) Globose cells with almost no stainability by Parker ink, show varying sizes (3–10lm in diameter), ×700. (b) Long septate hyphae of 40–70lm lengths, faintly stained by Parker ink, ×700. of varying sizes and septate hyphae were clearly demonstrated in the entire horny layer (Fig. 2b). Mycological examinations The keratotic material was removed and mounted in KOH and Parker ink. The fungal elements were composed mainly of two types of elements; globose to subglobose yeast cells and long septate hyphae. The yeast showed considerable variation in size (3–10lm in diameter) and were crowded in the keratotic material (Fig. 3a). The hyphae varied from 1·6 to 4lm in diameter and 40 to 70lm lengths, and were mixed with the yeast cells (Fig. 3b). A few hyphae were approximately 15lm in length. The keratotic material yielded creamy colonies on Sabouraud glucose agar without cycloheximide when covered with a layer of olive oil at 24°C. By microscopic observation, the colonies consisted of globose yeast cells, varying in size from 1·4 to 4·3lm in diameter, and occasionally with buds which were connected by a narrow base. No hyphae were seen. The morphology of the cultured fungus corresponded to the published descriptions of Pityrosporum orbiculare [2] which was first described by Gordon in 1951 [3] and is now known as Malassezia globosa [4]. Immunohistochemical examinations Although Malassezia was obtained from the keratotic material, the morphological features of the fungus seen in the KOH and Parker ink preparation hardly seemed to coincide with those reported in the literature [1]. Namely, it is well known that the globose to subglobose yeast cells of Malassezia typically range from 2–8lm in diameter [1]. The cells in culture show considerable variety in size [2]. The hyphae in pityriasis versicolor  1998 ISHAM, Medical Mycology, 36, 331–344 A unique case of pityriasis versicolor 333 Table 1 Morphological comparison between M. globosa and the fungal cells in the horny layer in the present case Globose cells Size Thickness of cell wall Length of hyphae Stainability with Parker ink M. globosa cells Fungal cells in the horny layer in the present case 2–8lm, uniform or varying† 0·1–0·2 lm‡ Short§ (10–40lm¶) Easily stained¶ 3–10 lm, varying 0·1–0·9lm Long (40–70lm) Hardly stained †The sizes of the cells are relatively uniform in the horny layer in vivo (personal communication from Dr Y. Soh), while they vary in culture [2]. ‡This value is quoted from [10]. §This finding is quoted from [1]. ¶This finding is quoted from [5]. scales are usually short (10–40lm) in length [1,5]. Furthermore, the organism in scrapings is easily stained deep blue with Parker ink [5] (Table 1). On the basis of our mycological findings, we were not certain whether the fungal elements observed in the skin lesion were identical to Malassezia. To identify the fungal elements, immunohistochemical examinations were carried out using specific antifungal antibodies; anti-M. globosa, antiCandida albicans, anti-Aspergillus fumigatus, anti-Fusarium anthophilum and anti-Trichosporon beigelii sera. The anti-M. globosa serum was produced by G. Midgley. Cultured cells of M. globosa were washed three times with sterile PBS and collected by centrifugation at 4000g for 10 min at room temperature. The packed cells were combined with an equal volume of ballotini (80 mesh, Difco, East Molesey, UK) and suspended in sufficient PBS to fill the chamber in a Bead Beater (Biospec Products, OK, USA). This chamber was placed in a reservoir of ice and water and the suspension ground for four periods of 1 min separated by an interval of 1 min. The suspension of broken cells was centrifuged at 20000g for 1h at 4°C and the supernatant saved. This cytoplasmic extract (CE) was d (...truncated)