Onychomycosis caused by Scytalidium dimidiatum. Report of two cases. Review of the taxonomy of the synanamorph and anamorph forms of this coelomycete

Abstract

SUMMARYThe authors report two cases of onychomycosis in the dystrophic form, one of them involving an HIV-positive patient, provoked by Scytalidium dimidiatum, previously called Scytalidium lignicola. The subject is reviewed from the taxonomic viewpoint, considering the anamorph Hendersonula toruloidea as a synonym of Nattrassia mangiferae, and having Scytalidium dimidiatum as the major synanamorph. According to many mycologists, Scytalidium hyalinum may be a separate species or a hyaline mutant of Scytalidium dimidiatum. Scytalidium lignicola Pesante 1957 was considered to be the type-species of the genus by ELLIS (1971) 13 and later to be a "conidial state" of Hendersonula toruloidea by the same author, today known as Nattrassia mangiferae. The microorganism lives only on the roots of certain plants (mainly Platanus and Pinus). It produces pycnidia and is not considered to be a pathogen, although it is considered as a possible emerging agent capable of provoking opportunistic fungal lesions. The importance of this topic as one of the most outstanding in fungal taxonomy, so likely to be modified over time, as well as its interest in the field of dermatologic mycology, are emphasized.

Disseminated Infection with Nattrassia mangiferae in an Immunosuppressed Patient

“…Reviews of the literature on N. mangiferae infections and infections due to Scytalidium species have been provided by Frankel and Rippon, Moore, and Sigler and Sutton (3,4,8,(11)(12)(13), but there have been very few reports of deep or disseminated infections. Reports have involved mycetoma (2) and subcutaneous abscesses of the foot (14), facial lesions (10), fungemia and abdominal abscesses (1), endophthalmitis following trauma (6), and abscess following trauma to the base of a finger (9).…”

Caso para Diagnóstico

“…1,2 Os agentes mais relacionados às melanoníquias fúngicas são: S. dimidiatum, Fusarium sp, Wangiella dermatitidis, Exophiala dermatitidis, Scopulariopsis brevicaulis, Aspergillus niger, Alternaria sp, Penicillium sp, Acremonium sp; porém, já foi descrita como causada por dermatófitos (T. rubrum) e leveduras (Candida sp). 3 A pigmentação melânica desse caso tem origem na estrutura celular fúngica, causando confusão com melanoníquias neoplásicas (melanoma, nevo, doença de Bowen, carcinoma espinocelular), medicamentosas, traumáticas (hematoma), bacterianas, virais (HPV), hormonais (doença de Addison) ou constitucionais (lentigo, pigmentação racial, síndro-me de Laugier-Hunziker). 1 Scytalidium dimidiatum, antes denominado S. lignicola e Hendersonula toluroidea, é fungo demáceo que causa infecção vegetal em árvores de clima tropical, descrito como patógeno humano em onicomicoses, dermatomicoses e feo-hifomicoses, principalmente acometendo imunossuprimidos, migrantes e esportistas.…”

“…Alguns autores admitem duas formas para o S. lignicola, a pigmentada (S. dimidiatum) e a não pigmentada (S. hialinum). 3,4 O traumatismo repetido pode ter favorecido o desenvolvimento da afecção no pé dominante, destacando a presença de fraturas transversais nas unhas. 4 O tratamento das formas superficiais é mais efetivo que as formas distais-laterais, paroníquias ou onicomatricoma.…”

Aspectos epidemiológicos de pacientes com lesões ungueais e cutâneas causadas por Scytalidium spp

“…4 Since then, there have been several changes in its taxonomic nomenclature. In a review by Lacaz et al (1999) it became established that Nattrassia mangiferae is an anamorphous form of the genus Scytalidium and synonym of Hendersonula toruloidea; Scytalidium dimidiatum is the sinanamorphous form and synonym of S. Lignicola; S. Hyalinum may be considered a separate species or a hyaline mutant of S. Dimidiatum. 5 S. dimidiatum is found in the soil and vegetation, but the natural habitat of S. hyalinum is unknown.…”

“…In a review by Lacaz et al (1999) it became established that Nattrassia mangiferae is an anamorphous form of the genus Scytalidium and synonym of Hendersonula toruloidea; Scytalidium dimidiatum is the sinanamorphous form and synonym of S. Lignicola; S. Hyalinum may be considered a separate species or a hyaline mutant of S. Dimidiatum. 5 S. dimidiatum is found in the soil and vegetation, but the natural habitat of S. hyalinum is unknown. 5,6,7 They are both etiologic agents of plantar, palmar, interdigital and ungual dermatomycoses, with lesions that are clinically indistinguishable from dermatophytoses.…”