Coexistence of onychomycosis and nail psoriasis and its correlation with systemic treatment

Background: Epidemiological studies indicate that onychomycosis may affect up to 79% of psoriatic patients. Onychomycosis in psoriatic patients is more commonly caused by yeasts comparing with non-psoriatic.

Objectives: Evaluate the prevalence of fungi in nail psoriasis. Evaluate the association between direct mycological examination (DME) and mycological culture, Nail Psoriasis Severity Index (NAPSI) and systemic treatment for psoriasis.

Methods: Of 133 nails from 20 patients with nail psoriasis were evaluated as follows: 9 patients were using topical treatment and 11 were on systemic treatment. The assessment of psoriasis severity using NAPSI was performed in all psoriatic nails. The presence of fungi was confirmed in DME and culture.

Results: DME showed the presence of fungal elements in 45 nails (33.83%) with a predominance of blastoconidia (95.5%) No septate hyphae were seen. Mycological culture was positive in 36 (27.06%) samples. Among them, Candida grew in 31 (86.1%): Candida parapsilosis in 15 (48.38%), Candida spp in 14 (45.16%). No growth of dermatophytes was observed. Patients with systemic treatment showed a higher frequency of positive test (DME and culture) for fungi when compared to topic treatment (p:.006). There was a positive correlation between NAPSI, mycological culture and systemic treatment (p:.0063); the risk was four times higher (OR:4.0).

Limitation of the study: Sample size.

Conclusion: These results are consistent with some previous reports, Candida was the fungus with higher frequency on the psoriatic nails, however, the role of these fungi is controversial (contamination x colonisation x infection). The fact that the immunosuppressive treatment increases the chance of fungal infection leads us to a greater attention to this patient profile, to prevent the intensification of nail psoriasis (Köbner phenomenon).