Clinical and Experimental Dermatology
An unusual cutaneous souvenir C. Wlodek,1 E. M. Johnson,2 L. Biddlestone,1 I. Mauri-Sole1 and C. R. Lovell1 1
Royal United Hospital, Bath, UK; and 2Public Health England Mycology Reference Laboratory, Bristol, UK
doi: 10.1111/ced.12442
Clinical findings A 36-year-old woman presented with a lesion on her right ankle. A few days before, she had returned from a volunteering trip to Costa Rica, where she had been camping in a field next to a pig farm while helping to build a school. During this time, she had sustained several insect bites, but one of the lesions, on her right ankle, had blistered and was enlarging. The area had not responded to topical hydrocortisone. She had no systemic symptoms. There was no history of immunosuppression, and she was not on any medication. On physical examination, a well-demarcated, indurated oozing plaque, 30 mm in size, with peripheral blisters, was seen on the skin of the right ankle (Fig. 1). The working diagnosis was an infected insect bite. A punch biopsy was taken, and the patient was treated with a topical steroid and an antibacterial wash. After 2 weeks of treatment, there was only minimal improvement, with persistent nodularity at the peripheral edge with new hyperkeratosis. Skin scrapings were taken at this point.
Histopathological and other findings
Figure 1 Clinical appearance of the lesion, on the posterior right
ankle, at the time of biopsy.
walled, two-celled macroconidia were seen, with some club-shaped microconidia spaced along the hyphae (Fig. 4). What is your diagnosis?
The biopsy showed epidermal spongiosis with vesiculation and a marked eosinophil-rich infiltrate in the dermis extending to the subcutis. No parasites were seen, and PCR for Leishmania was negative. Periodic-acid– Schiff staining revealed fungal spores and hyphae in the surface keratin (Fig. 2). Direct microscopy was positive for fungal hyphae. Culture at 28 °C yielded a spreading, powdery, buffcoloured colony with a radiating red-brown reverse (Fig. 3). On microscopy, abundant distinctive roughCorrespondence: Dr Christina Wlodek, Department of Dermatology, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK E-mail: [email protected] Conflict of interest: the authors declare that they have no conflicts of interest. Accepted for publication 28 March 2014
ª 2014 British Association of Dermatologists
Clinical and Experimental Dermatology (2014) 40, pp91–93
91
D CP
CED
CPD • Clinicopathological case
D
CP
Clinicopathological case
(a)
(a)
(b)
(b)
Figure 2 (a) Spongiosis of the epidermis with intra and subepider-
mal vesicles containing eosinophils. The dermis contained a superficial and deep, predominantly perivascular inflammatory cell infiltrate, with numerous eosinophils. No leishmania parasites were identified (haematoxylin and eosin, original magnification 9 100). (b) Numerous fungal spores and hyphae in the surface keratin (periodic-acid–Schiff, original magnification 9300). Figure 3 Culture plate of Microsporum nanum viewed from (a)
the top and (b) from the under surface of the plate.
Diagnosis Tinea corporis due to Microsporum nanum.
Discussion M. nanum is a pathogenic fungus of the family Arthrodermataceae. It is a dermatophyte, which invades dead keratinized tissue including skin, hair and nails. It is both zoophilic and geophilic. The commonest natural hosts are pigs and sheep. It was first reported in 1954 by Fuentes et al.,1 when it was isolated from a scalp kerion in a Cuban child. It rarely infects humans, but when it does, there is almost invariably an association with pig farming. M. nanum has on
92
Clinical and Experimental Dermatology (2014) 40, pp91–93
several occasions been cultured from soil samples where pigs have been pastured. The dermatophyte spores can remain viable for many years in a dry and cool environment.2 This dermatophyte has a worldwide distribution. The first European reported case of M. nanum infection was associated with a farm in Italy, and dates back to 1976.3 Two more cases were reported in Australia in the same year.4 The first case of tinea corporis secondary to M. nanum from the African continent was reported in 1995, in a patient who reared pigs. A study from eastern Nepal, looking at 69 patients with tinea capitis, found 2.56% of cases to be due to M. nanum.5 Brazil has also recorded cases of onychomycosis due to this organism.6
ª 2014 British Association of Dermatologists
D CP Clinicopathological case
References
Figure 4 Distinctive rough-walled, two-celled macroconidia
characteristic of Microsporum nanum (original magnification 9 600).
1 Fuentes C, Aboulafia R, Vidal R. A dwarf form of Microsporum gypseum. J Invest Dermatol 1954; 23: 51–61. 2 Garcıa-S anchez A, Baz an J, de Mendoza JH et al. Outbreak of ringworm in a traditional Iberian pig farm in Spain. Mycoses 2011; 54: 179–81. 3 Morganti L, Bianchedi M, Ajello L, Padhye A. First European report of swine infection by Microsporum nanum. Mycopathologia 1976; 59: 179–82. 4 Turner TW, Kaminski GW. Microsporum nanum infection in South Australia. Med J Aust 1976; 1: 743–4. 5 Jha BN, Garg VK, Agrawal S et al. Tinea capitis in eastern Nepal. Int J Dermatol 2006; 45: 100–2. 6 Martinez E, Ameen M, Tejada D, Arenas R. Microsporum spp. onychomycosis: disease presentation, risk factors and treatment responses in an urban population. Braz J Infect Dis 2014; 18: 181–6.
Standard dermatophyte treatment should be effective, but in refractory cases, susceptibility testing of the isolate can be used to guide management. In this case, there was complete resolution with topical miconazole and a 1 month course of oral terbinafine 250 mg daily. In conclusion, M. nanum is a dermatophyte, which rarely causes infection in humans. Infection usually follows direct contact with its commonest natural host, the pig, or with soil that contains spores or infected skin squames or shed hairs. A history of contact with pigs should therefore raise the suspicion of such an infection.
Learning points
•
M. nanum is a geophilic and zoophilic dermatophyte. • Its main reservoir is swine. • M. nanum has a characteristic microscopic morphology, producing roughened two-celled macroconidia. • This case highlights the importance of taking fungal scrapings before treating empirically, particularly if oral antifungal agents prove necessary.
ª 2014 British Association of Dermatologists
Clinical and Experimental Dermatology (2014) 40, pp91–93
93
An unusual cutaneous souvenir C. Wlodek,1 E. M. Johnson,2 L. Biddlestone,1 I. Mauri-Sole1 and C. R. Lovell1 1
Royal United Hospital, Bath, UK; and 2Public Health England Mycology Reference Laboratory, Bristol, UK
doi: 10.1111/ced.12442
Clinical findings A 36-year-old woman presented with a lesion on her right ankle. A few days before, she had returned from a volunteering trip to Costa Rica, where she had been camping in a field next to a pig farm while helping to build a school. During this time, she had sustained several insect bites, but one of the lesions, on her right ankle, had blistered and was enlarging. The area had not responded to topical hydrocortisone. She had no systemic symptoms. There was no history of immunosuppression, and she was not on any medication. On physical examination, a well-demarcated, indurated oozing plaque, 30 mm in size, with peripheral blisters, was seen on the skin of the right ankle (Fig. 1). The working diagnosis was an infected insect bite. A punch biopsy was taken, and the patient was treated with a topical steroid and an antibacterial wash. After 2 weeks of treatment, there was only minimal improvement, with persistent nodularity at the peripheral edge with new hyperkeratosis. Skin scrapings were taken at this point.
Histopathological and other findings
Figure 1 Clinical appearance of the lesion, on the posterior right
ankle, at the time of biopsy.
walled, two-celled macroconidia were seen, with some club-shaped microconidia spaced along the hyphae (Fig. 4). What is your diagnosis?
The biopsy showed epidermal spongiosis with vesiculation and a marked eosinophil-rich infiltrate in the dermis extending to the subcutis. No parasites were seen, and PCR for Leishmania was negative. Periodic-acid– Schiff staining revealed fungal spores and hyphae in the surface keratin (Fig. 2). Direct microscopy was positive for fungal hyphae. Culture at 28 °C yielded a spreading, powdery, buffcoloured colony with a radiating red-brown reverse (Fig. 3). On microscopy, abundant distinctive roughCorrespondence: Dr Christina Wlodek, Department of Dermatology, Bristol Royal Infirmary, Upper Maudlin Street, Bristol BS2 8HW, UK E-mail: [email protected] Conflict of interest: the authors declare that they have no conflicts of interest. Accepted for publication 28 March 2014
ª 2014 British Association of Dermatologists
Clinical and Experimental Dermatology (2014) 40, pp91–93
91
D CP
CED
CPD • Clinicopathological case
D
CP
Clinicopathological case
(a)
(a)
(b)
(b)
Figure 2 (a) Spongiosis of the epidermis with intra and subepider-
mal vesicles containing eosinophils. The dermis contained a superficial and deep, predominantly perivascular inflammatory cell infiltrate, with numerous eosinophils. No leishmania parasites were identified (haematoxylin and eosin, original magnification 9 100). (b) Numerous fungal spores and hyphae in the surface keratin (periodic-acid–Schiff, original magnification 9300). Figure 3 Culture plate of Microsporum nanum viewed from (a)
the top and (b) from the under surface of the plate.
Diagnosis Tinea corporis due to Microsporum nanum.
Discussion M. nanum is a pathogenic fungus of the family Arthrodermataceae. It is a dermatophyte, which invades dead keratinized tissue including skin, hair and nails. It is both zoophilic and geophilic. The commonest natural hosts are pigs and sheep. It was first reported in 1954 by Fuentes et al.,1 when it was isolated from a scalp kerion in a Cuban child. It rarely infects humans, but when it does, there is almost invariably an association with pig farming. M. nanum has on
92
Clinical and Experimental Dermatology (2014) 40, pp91–93
several occasions been cultured from soil samples where pigs have been pastured. The dermatophyte spores can remain viable for many years in a dry and cool environment.2 This dermatophyte has a worldwide distribution. The first European reported case of M. nanum infection was associated with a farm in Italy, and dates back to 1976.3 Two more cases were reported in Australia in the same year.4 The first case of tinea corporis secondary to M. nanum from the African continent was reported in 1995, in a patient who reared pigs. A study from eastern Nepal, looking at 69 patients with tinea capitis, found 2.56% of cases to be due to M. nanum.5 Brazil has also recorded cases of onychomycosis due to this organism.6
ª 2014 British Association of Dermatologists
D CP Clinicopathological case
References
Figure 4 Distinctive rough-walled, two-celled macroconidia
characteristic of Microsporum nanum (original magnification 9 600).
1 Fuentes C, Aboulafia R, Vidal R. A dwarf form of Microsporum gypseum. J Invest Dermatol 1954; 23: 51–61. 2 Garcıa-S anchez A, Baz an J, de Mendoza JH et al. Outbreak of ringworm in a traditional Iberian pig farm in Spain. Mycoses 2011; 54: 179–81. 3 Morganti L, Bianchedi M, Ajello L, Padhye A. First European report of swine infection by Microsporum nanum. Mycopathologia 1976; 59: 179–82. 4 Turner TW, Kaminski GW. Microsporum nanum infection in South Australia. Med J Aust 1976; 1: 743–4. 5 Jha BN, Garg VK, Agrawal S et al. Tinea capitis in eastern Nepal. Int J Dermatol 2006; 45: 100–2. 6 Martinez E, Ameen M, Tejada D, Arenas R. Microsporum spp. onychomycosis: disease presentation, risk factors and treatment responses in an urban population. Braz J Infect Dis 2014; 18: 181–6.
Standard dermatophyte treatment should be effective, but in refractory cases, susceptibility testing of the isolate can be used to guide management. In this case, there was complete resolution with topical miconazole and a 1 month course of oral terbinafine 250 mg daily. In conclusion, M. nanum is a dermatophyte, which rarely causes infection in humans. Infection usually follows direct contact with its commonest natural host, the pig, or with soil that contains spores or infected skin squames or shed hairs. A history of contact with pigs should therefore raise the suspicion of such an infection.
Learning points
•
M. nanum is a geophilic and zoophilic dermatophyte. • Its main reservoir is swine. • M. nanum has a characteristic microscopic morphology, producing roughened two-celled macroconidia. • This case highlights the importance of taking fungal scrapings before treating empirically, particularly if oral antifungal agents prove necessary.
ª 2014 British Association of Dermatologists
Clinical and Experimental Dermatology (2014) 40, pp91–93
93
